Screening and Diagnosis

DISCLAIMER – The Autism Resource Foundation provides general information to the autism community. The information comes from a variety of sources, and the Autism Resource Foundation does not independently verify any of it, nor does it necessarily reflect the views and/or opinions of the Autism Resource Foundation. Nothing on this website should be construed as medical advice. Always consult your doctor regarding the needs of your family.

About.com:  Autism
Screening and Diagnosis of Autism

The media is filled with stories of a dramatic rise in autism diagnoses. Parents worry that any difference in their child's behavior or development could be a sign of a lifelong disability. Sometimes these worries are unnecessary. Other times, careful observation can lead to early diagnosis, early treatment, and, with luck, a positive outcome.

Noticing Early Signs of Autism
If you think that you or someone you love may be autistic, you'll probably have noticed certain symptoms. Perhaps you've observed a lack of eye contact, difficulty with social relationships, speech delays, or odd physical behaviors such as rocking, finger flicking or toe walking. These are the "red flags" that suggest something might be wrong -- and that something might be autism.
Early Signs of Autism
What Are the Signs of Autism in Children?
Autism May Be Diagnosable at Birth
Should I Wait to Have My Child Diagnosed with Autism?

Selecting a Professional to Screen for and Diagnose Autism
Once you've determined that something may be amiss, it's a good idea to seek a professional to screen for autism.

The "right" professional may be a psychologist, a developmental pediatrician or a pediatric neurologist -- but the most important criteria is that the expert you choose has experience with and knowledge of autism spectrum disorders.
Who Should Diagnose Autism Spectrum Disorders?
Can Teachers Diagnose Autism?
Autism: Seeking A Diagnosis
Autism Specialists 101

How Do Professionals Screen for and Diagnose Autism?
Because autism cannot be diagnosed with a medical test, screening and diagnosis involves interviews, observation and evaluations. Even when a professional provides an opinion, the opinion may be couched in such terms as "it LOOKS like a pervasive developmental disorder, but your child doesn't have all the symptoms of autism." While this kind of uncertainty can be extemely frustrating, it's sometimes unavoidable -- and even clearcut autism diagnoses can change over time.
Screening for Autism
How Is Autism Diagnosed?

After the Autism Diagnosis
For many families, an autism diagnosis can be overwhelming. It seems to change everything, and it can affect your relationship with your spouse, your friends, and your child. But your child is still the person he or she always was -- and there's plenty of help, hope and support available.
What to Do After the Autism Diagnosis
What If...? Getting Past Blame and Worry to Help Your Autistic Child
Top Ten Autism Sites
Joining the Autism Community

American Academy of Neurology
AAN Guideline Summary For CLINICIANS

This is a summary of the American Academy of Neurology (AAN) and Child Neurology Society (CNS) guideline on screening and diagnosis for autism. This practice parameter reviews the available empirical evidence and gives specific recommendations for the identification of children with autism. This approach requires a dual process: 1) routine developmental surveillance and screening specifically for autism to be performed on all children to first identify those at risk for any type of atypical development, and to identify those specifically at risk for autism; and 2) to diagnose and evaluate autism, to differentiate autism from other developmental disorders.

Screening And Diagnosis Of Autism

LEVEL ONE: Routine developmental surveillance screening specifically for autism
Good Evidence Supports
Developmental surveillance should be performed at all well-child visits from infancy through school-age, and at any age thereafter if concerns are raised about social acceptance, learning, or behavior (Level* B).
Recommended developmental screening tools include the Ages and Stages Questionnaire, the BRIGANCE® Screens, the Child Development Inventories, and the Parents’ Evaluations of Developmental Status (Level B).
Because of the lack of sensitivity and specificity, the Denver-II (DDST-II) and the Revised Denver Pre-Screening Developmental Questionnaire (R-DPDQ) are not recommended for appropriate primary-care developmental surveillance (Level B).
Further developmental evaluation is required whenever a child fails to meet any of the following milestones (Level B): babbling by 12 months; gesturing (e.g., pointing, waving bye-bye) by 12 months; single words by 16 months; two-word spontaneous (not just echolalic) phrases by 24 months; loss of any language or social skills at any age.
Siblings of children with autism should be carefully monitored for acquisition of social, communication, and play skills, and the occurrence of maladaptive behaviors. Screening should be performed not only for autism-related symptoms but also for language delays, learning difficulties, social problems, and anxiety or depressive symptoms (Level B).
Screening specifically for autism should be performed on all children failing routine developmental surveillance procedures using one of the validated instruments—the CHAT or the Autism Screening Questionnaire (Level B).
Laboratory investigations recommended for any child with developmental delay and/or autism include audiologic assessment and lead screening (Level B). Early referral for a formal audiologic assessment should include behavioral audiometric measures, assessment of middle ear function, and electrophysiologic procedures using experienced pediatric audiologists with current audiologic testing methods and technologies (Level B). Lead screening should be performed in any child with developmental delay and pica. Additional periodic screening should be considered if the pica persists (Level B).

LEVEL TWO: Diagnosis and evaluation of autism
Strong Evidence Supports
Genetic testing in children with autism, specifically high resolution chromosome studies (karyotype) and DNA analysis for FraX, should be performed in the presence of mental retardation (or if mental retardation cannot be excluded), if there is a family history of FraX or undiagnosed mental retardation, or if dysmorphic features are present (Level A). However, there is little likelihood of positive karyotype or FraX testing in the presence of high-functioning autism.
Selective metabolic testing (Level A) should be initiated by the presence of suggestive clinical and physical findings such as the following: if lethargy, cyclic vomiting, or early seizures are evident; the presence of dysmorphic or coarse features; evidence of mental retardation or if mental retardation cannot be ruled out; or if occurrence or adequacy of newborn screening at birth is questionable.

Good Evidence Supports
There is inadequate evidence at the present time to recommend an EEG study in all individuals with autism. Indications for an adequate sleep-deprived EEG with appropriate sampling of slow wave sleep include (Level B) clinical seizures or suspicion of subclinical seizures, and a history of regression (clinically significant loss of social and communicative function) at any age, but especially in toddlers and preschoolers.
Recording of event-related potentials and magnetoencephalography are research tools at the present time, without evidence of routine clinical utility (Level B).
There is no clinical evidence to support the role of routine clinical neuroimaging in the diagnostic evaluation of autism, even in the presence of megalencephaly (Level B).
There is inadequate supporting evidence for hair analysis, celiac antibodies, allergy testing (particularly food allergies for gluten, casein, candida, and other molds), immunologic or neurochemical abnormalities, micronutrients such as vitamin levels, intestinal permeability studies, stool analysis, urinary peptides, mitochondrial disorders (including lactate and pyruvate), thyroid function tests, or erythrocyte glutathione peroxidase studies (Level B).

This guideline summary is evidence-based. The AAN uses the following definitions for the level of recommendation and classification of evidence. *Definitions for strength of the recommendations: Level A: Established as effective, ineffective or harmful, (or established as useful/predictive or not useful/predictive) for the given condition in the specified population. Level B: Probably effective, ineffective or harmful (or probably useful predictive or not useful/predictive) for the given condition in the specified population. Level C: Possibly effective, ineffective or harmful (or possibly useful predictive or not useful/predictive) for the given condition in the specified population. Level U: Data inadequate or conflicting. Given current knowledge, treatment (test, predictor) is unproven.

This is an educational service of the American Academy of Neurology. It is designed to provide members with evidence-based guideline recommendations to assist with decision-making in patient care. It is based on an assessment of current scientific and clinical information, and is not intended to exclude any reasonable alternative methodologies. The AAN recognizes that specific patient care decisions are the prerogative of the patient and the physician caring for the patient, based on the circumstances involved. Physicians are encouraged to carefully review the full AAN guidelines so they understand all recommendations associated with care of these patients.

American Academy of Pediatrics
Practice Parameter: Screening And Diagnosis Of Autism

Abstract: The American Academy of Pediatrics endorses and accepts as its policy the Practice Parameter: Screening and diagnosis of autism.
Article Abstract. Autism is a common disorder of childhood, affecting 1 in 500 children. Yet, it often remains unrecognized and undiagnosed until or after late preschool age because appropriate tools for routine developmental screening and screening specifically for autism have not been available. Early identification of children with autism and intensive, early intervention during the toddler and preschool years improves outcome for most young children with autism. This practice parameter reviews the available empirical evidence and gives specific recommendations for the identification of children with autism. This approach requires a dual process: 1) routine developmental surveillance and screening specifically for autism to be performed on all children to first identify those at risk for any type of atypical development, and to identify those specifically at risk for autism; and 2) to diagnose and evaluate autism, to differentiate autism from other developmental disorders. NEUROLOGY 2000;55:468-479.

The Guidelines are available as a PDF file from the American Academy of Neurology Web site free-of-charge at: http://www.aan.com/professionals/practice/pdfs/gl0063.pdf. (Adobe Acrobat PDF format)

Autism Society of America (ASA)
Diagnosis and Consultation
There are no medical tests for diagnosing autism. An accurate diagnosis must be based on observation of the individual's communication, behavior, and developmental levels. However, because many of the behaviors associated with autism are shared by other disorders, various medical tests may be ordered to rule out or identify other possible causes of the symptoms being exhibited. At first glance, some persons with autism may appear to have mental retardation, a behavior disorder, problems with hearing, or even odd and eccentric behavior. To complicate matters further, these conditions can co-occur with autism. However, it is important to distinguish autism from other conditions, since an accurate diagnosis and early identification can provide the basis for building an appropriate and effective educational and treatment program.

A brief observation in a single setting cannot present a true picture of an individual's abilities and behaviors. Parental (and other caregivers' and/or teachers) input and developmental history are very important components of making an accurate diagnosis.

Early Diagnosis
Research indicates that early diagnosis is associated with dramatically better outcomes for individuals with autism. The earlier a child is diagnosed, the earlier the child can begin benefiting from one of the many specialized intervention approaches treatment and education

Diagnostic Tools
The characteristic behaviors of autism spectrum disorders may or may not be apparent in infancy (18 to 24 months), but usually become obvious during early childhood (24 months to 6 years).

As part of a well-baby/well-child visit, your child's doctor should do a "developmental screening" asking specific questions about your baby's progress. The National Institute of Child Health and Human Development (NICHD) lists five behaviors that signal further evaluation is warranted:
Does not babble or coo by 12 months
Does not gesture (point, wave, grasp) by 12 months
Does not say single words by 16 months
Does not say two-word phrases on his or her own by 24 months
Has any loss of any language or social skill at any age.

Having any of these five "red flags" does not mean your child has autism. But because the characteristics of the disorder vary so much, a child showing these behaviors should have further evaluations by a multidisciplinary team. This team may include a neurologist, psychologist, developmental pediatrician, speech/language therapist, learning consultant, or other professionals knowledgeable about autism.

Screening Instruments
While there is no one behavioral or communications test that can detect autism, several screening instruments have been developed that are now being used in diagnosing autism:
CARS rating system (Childhood Autism Rating Scale), developed by Eric Schopler in the early 1970s, is based on observed behavior. Using a 15-point scale, professionals evaluate a child's relationship to people, body use, adaptation to change, listening response, and verbal communication.
The Checklist for Autism in Toddlers (CHAT) is used to screen for autism at 18 months of age. It was developed by Simon Baron-Cohen in the early 1990s to see if autism could be detected in children as young as 18 months. The screening tool uses a short questionnaire with two sections, one prepared by the parents, the other by the child's family doctor or pediatrician.
The Autism Screening Questionnaire is a 40 item screening scale that has been used with children four and older to help evaluate communication skills and social functioning.
The Screening Test for Autism in Two-Year Olds is being developed by Wendy Stone at Vanderbilt and uses direct observations to study behavioral features in children under two. She has identified three skills areas that seem to indicate autism - play, motor imitation, and joint attention.

Consulting With Professionals
Whether you or your child's pediatrician is the first to suspect autism, your child will need to be referred to someone who specializes in diagnosing autism spectrum disorders. This may be a developmental pediatrician, a psychiatrist or psychologist, and other professionals that are better able to observe and test your child in specific areas.

This multidisciplinary assessment team may include some or all of the following professionals (they may also be involved in treatment programs):

Developmental pediatrician - Treats health problems of children with developmental delays or handicaps.
Child psychiatrist - A medical doctor who may be involved in the initial diagnosis. He/she can also prescribe medication and provide help in behavior, emotional adjustment and social relationships).
Clinical psychologist - Specializes in understanding the nature and impact of developmental disabilities, including autism spectrum disorders. May perform psychological and assessment test, as well as help with behavior modification and social skills training.
Occupational therapist - Focuses on practical, self-help skills that will aid in daily living such as dressing and eating. May also work on sensory integration, coordination of movement, and fine motor skills.
Physical therapist - Helps to improve the use of bones, muscles, joints, and nerves to develop muscle strength, coordination and motor skills.
Speech/language therapist - Involved in the improvement of communication skills, including speech and language.
Social Worker - May provide counseling services or act as case manager helping to arrange services and treatments.

It is important that parents and professionals work together for the child's benefit. While professionals will use their experience and training to make recommendations about your child's treatment options, you have unique knowledge about his/her needs and abilities that should be taken into account for a more individualized course of action.

Once a treatment program is in place, communication between parents and professionals is essential in monitoring the child's progress. Here are some guidelines for working with professionals:
Be informed. Learn as much as you can about your child's disability so you can be an active participant in determining care. If you don't understand terms used by professionals, ask for clarification.
Be prepared. Be prepared for meetings with doctors, therapists, and school personnel. Write down your questions and concerns, and then note the answers.
Be organized. Many parents find it useful to keep a notebook detailing their child's diagnosis and treatment, as well as meetings with professionals.
Communicate. It's important to ensure open communication - both good and bad. If you don't agree with a professional's recommendation, speak up and say specifically why you don't.

First Signs

Autism Screening

Autism is a common developmental disorder, but it can be difficult to identify in a young child. Increasingly, physicians have been called upon to perform routine autism screenings. All autism spectrum disorders are defined by deficits in three core areas1:

• social skills
• communication
• behavior and interests

In 2000, a recent practice parameter from the American Academy of Neurology, which was supported by the American Academy of Pediatrics, called for the routine screening of all children for autism.

"Autism is a common disorder of childhood. Yet, it often remains unrecognized and undiagnosed until or after late preschool age because appropriate tools for routine developmental screening and screening specifically for autism have not been available. Early identification of children with autism and intensive, early intervention during the toddler and preschool years improves outcome for most young children with autism.” (Abstract of Practice parameter: Screening and diagnosis of autism. Neurology 2000, 55: 468-79.)

As stated above, routine screening is crucial because of autism’s prevalence, the difficulty in diagnosing the disorder, and because children with autism who receive early identification and intensive intervention have the best prognosis. Despite these reasons and recommendations, most children are never screened for autism. However, when a routine developmental screening raises concerns, or a child is at risk of atypical development, an autism screening is imperative.

The term “autism” refers to a wide range of autism spectrum disorders, from a child with “classic” autism who is non-verbal and asocial, to a high-functioning child with idiosyncratic social skills, play, and language. (Please see Autism Spectrum Disorders for a more detailed explanation of the various clinical categories of autism.) All autism spectrum disorders are defined by deficits in three core areas: social skills, communication, and behavior and interests. Because these deficits may be mild, autism can be difficult for a physician to identify, especially without special training or within a busy medical practice.

The basic screening for autism is as simple as the disorder is complex, taking less than five minutes. There are a variety of screening tools for autism, but they share a common goal. An autism screening enables a physician to target the three core areas of the disorder through a combination of observation and interaction. (For more information about autism screening tools, including examples, please see the Screening Tools section.)

Screening Tools
In our efforts to promote early identification of developmental disorders in young children, First Signs, Inc. has conducted an extensive review of current screening tools. This section serves as an overview of, and introduction to, the practice of routine screening by pediatric clinicians.
In this section, you will find information about:

• Screening Tool Selection Criteria
• Psychometric Terms
• Recommended Screening Tools
• References
   

How are screening tools used?

Screening tools are brief measures that differentiate children who are at risk for atypical development from those who are not. They range from effective questionnaires given to parents in waiting rooms to brief, but purposeful, give-and-take exchanges and observations during pediatric exams. Often, screening tools can help eliminate worries of developmental delays, by screening children “out,” rather than “in.”

Screening by itself does not provide a diagnosis, but is the first key step in the diagnostic process. Therefore, it is important for health care providers to immediately refer those flagged as “at risk” during screening to diagnostic specialists for more extensive diagnostic evaluation and referral for appropriate intervention. Please visit our Screening Process section for key guidelines about screening, referral, and diagnosis.

Screening tools have applications for physicians, healthcare providers, clinics, day care center providers, schools, parents, and others who work with young children. Screening tools are available to identify a variety of concerns from broad-based developmental disorders to autism spectrum disorders to other related disorders, such as attention deficit disorder and bipolar disorder.

Our current focus is developmental and autism spectrum disorders. Please revisit this Web section in the future as we expand our list of disorders and related screening tools.

Screening recommended at every well visit

In recent years, leading medical organizations have issued a number of policy statements that provide guidelines for the screening and diagnosis of autism spectrum disorders and call for routine developmental screening in young children. In keeping with these statements, First Signs recommends that a physician or trained nurse practitioner perform a routine developmental screening at every well visit starting at four months of age.

First Signs recommends that physicians conduct developmental screening at every well child visit (minimally, at all well visits between 12 and 36-months) for any type of atypical development. If the developmental screening indicates a concern, a simple autism screening should be performed, along with a formal audiological assessment, a lead screen for pica, and a referral to Early Intervention and to a specialist for a developmental evaluation. If the autism screening flags a potential problem, the child should be should be referred to a specialist for formal diagnostic testing. For older verbal children (ages 4 and older), an Asperger Syndrome screen may be appropriate with referral to a diagnostic specialist.

Why are screening tools important?

Screening tools encourage routine and systematic surveillance of developmental milestones and concerns. Many high quality screening tools rely upon parent report, which has been proven to increase screening tool accuracy. They stimulate dialogue between practitioners and parents about the more subtle aspects of development—social, emotional, and communication. Looking more carefully and qualitatively at developmental milestones allows parents’ concerns to be addressed in a timely manner and improves outcomes for all children, not just those challenged by autism and developmental disorders.

First Signs recommends “sensitive” screening tools over screening tools with high “specificity” (those proven to identify children at risk vs. those that screen out children who are not at risk), since the prevalence of children with autism spectrum and other childhood disorders is dramatically on the rise. By identifying as many children as possible as early as possible, effective interventions can begin immediately. Only with consistent and intensive intervention, will children with autism and related disorders experience real improvement.

Screening tools and related information to help clinicians

To assist physicians and other healthcare providers in the screening process, First Signs has provided information and ratings on several validated screening tools that are brief, accurate, and cost-effective. The Screening Tools section gives physicians and other healthcare providers access to information about the best screening tools currently available.

Furthermore, we have developed the First Signs Screening Kit, which includes several highly validated screening tools, screening guidelines, an educational video, a developmental milestones wall chart, and an Early Intervention referral guide.

The future of screening in early childhood

First Signs will follow the introduction of newer and more improved screening tools as they are developed, field tested, and normed on large populations of children in years to come. Our recommended screening tools will keep in step with such changes so that we always offer physicians, professionals, and parents the most current information on screening tools available.

Help Guide.org

Autism Diagnosis and Treatment: Getting Professional Help for Your Child

If you’ve spotted warning signs of autism in your child, it’s important to get a medical evaluation to either confirm or rule out the disorder. However, diagnosing autism is not always a quick ‘n easy process. The good news is that you don’t need an autism diagnosis to begin seeking treatment for your child’s symptoms. Early intervention makes a big difference with all developmental delays, so don’t wait! Start researching your autism treatment options and get your kid into therapy as soon as possible.

Note to parents

The road to an autism diagnosis can be difficult and time-consuming. According to the American Academy of Neurology, it is often 2 to 3 years after the first symptoms of autism are recognized before an official diagnosis is made. This is due in large part to concerns about labeling or incorrectly diagnosing the child. However, an autism diagnosis can also be delayed if the doctor doesn’t take a parent’s concerns seriously or if the family isn’t referred to health care professionals who specialize in developmental disorders.

If you’re worried that your child has autism, it’s important to seek out a medical diagnosis. But don’t wait for that diagnosis to get your child into treatment. Early intervention during the preschool years will improve your child’s chances for overcoming his or her developmental delays. So look into treatment options and try not to worry if you’re still waiting on a definitive diagnosis. Putting a potential label on your kid’s problem is far outweighed by the need to treat the symptoms.

Diagnosing autism spectrum disorders

In order to determine whether your child has autism, a related autism spectrum disorder, or another developmental condition, clinicians look carefully at the way your child socializes, communicates, and behaves. Diagnosis is based on the patterns of behavior that are revealed.

If you are concerned that your child has an autism spectrum disorder and developmental screening confirms the risk, ask your family doctor or pediatrician to refer you immediately to an autism specialist or team of specialists for a comprehensive evaluation. Since the diagnosis of autism is complicated, it is essential that you meet with experts who have training and experience in this highly-specialized area.

The team of specialists involved in diagnosing your child may include a:

• Child psychologist
• Child psychiatrist
• Speech pathologist
• Developmental pediatrician
• Pediatric neurologist
• Audiologist
• Physical therapist
• Special education teacher

The Diagnostic Evaluation

Diagnosing autism is not a brief process. There is no single medical test that can diagnose it definitively; instead, in order to accurately pinpoint your child's problem, multiple evaluations and tests are necessary.

Autism Spectrum Disorders Diagnosis

• Parent/Caregiver Interview

In the first phase of the diagnostic evaluation, you will give your doctor background information about your child’s medical, developmental, and behavioral history. If you have been keeping a journal or taking notes on anything that concerned you, turn over that information. The doctor will also want to know about your family’s medical and mental health history.

• Medical Evaluation

The medical evaluation includes a general physical, a neurological exam, lab tests, and genetic testing. You child will undergo this full screening to determine the cause of his or her developmental problems and to identify any co-existing conditions.

• Hearing Tests

Since hearing problems can result in social and language delays, they need to be excluded before autism can be diagnosed. Your child will undergo a formal audiological assessment where he or she is tested for any hearing impairments, as well as any other hearing issues or sound sensitivities that sometimes co-occur with autism.

• Direct Behavior Observation

Developmental specialists will observe your child in a variety of settings to look for unusual behavior associated with the autism spectrum disorders. They may watch your child playing or interacting with other people.

• Lead Screening

Because lead poisoning can cause autistic-like symptoms, the National Center for Environmental Health recommends that all children with developmental delays be screened for lead poisoning

Depending on your child's & symptoms and their severity, the diagnostic assessment may also include speech, intelligence, social, sensory processing, and motor skills testing. These tests can be helpful not only in diagnosing autism, but also for determining what type of treatment your child needs:

• Speech and Language Evaluation - A speech pathologist will evaluate your child's speech and communication abilities for signs of autism, as well as looking for any indicators of specific language impairments or disorders.
• Cognitive Testing - Your child may be given a standardized intelligence test or an informal cognitive assessment. Cognitive testing can help differentiate autism from other disabilities.
• Adaptive Functioning Assessment - Your child may be evaluated for their ability to function, problem-solve, and adapt in real life situations. This may include testing social, nonverbal, and verbal skills, as well as the ability to perform daily tasks such as dressing and feeding him or herself.
• Sensory-motor Evaluation - Since sensory integration dysfunction often co-occurs with autism, and can even be confused with it, a physical therapist or occupational therapist may assess your child's fine motor, gross motor, and sensory processing skills.

Autistic Children and IQ Tests

If your child’s intelligence is being assessed, ask for an IQ test that doesn’t require language abilities, such as the Test for Nonverbal Intelligence (TONI).

Related medical conditions

There are several medical conditions which occur more frequently in people with autism than in the general population. Because of the increased risk, it is a good idea to familiarize yourself if your child has autism or other developmental delays.

• Mental Retardation – Some children on the autism spectrum may suffer from mental retardation. While it is commonly stated that up to 75% of autistic individuals are cognitively impaired, new studies are challenging this statistic. This includes the latest autism population survey from the Centers for Disease Control. One of the reasons that mental retardation may be over-reported in autistic kids is that traditional IQ tests require strong verbal skills. Verbally-based tests don’t accurately measure intelligence in autistic children with speech problems. For further info: Utah Dept. of Health
• Seizures – One in four autistic children develop epileptic seizures, typically during adolescence. It is believed that the seizures are triggered by hormonal changes. The seizures may be noticeable, with clear symptoms such as convulsions, blacking out, or odd body movements. However for some, the seizures are not quite so obvious. In these cases, tantrums, self-injury, little academic progress during the teen years, or a loss of previously-acquired behavioral skills may be subtle signs of a subclinical seizure disorder. For further info: Epilepsy Ontario
• Fragile X Syndrome – Children with autism are at a higher risk for the genetic disorder Fragile X syndrome. Fragile X syndrome is the most common cause of mental retardation and results from a defect on the X chromosome. The syndrome affects approximately 2-5% of autistic individuals. For further info: The National Fragile X Foundation
• Tuberous Sclerosis – Tuberous sclerosis is a rare genetic disorder that causes benign tumors to grow in many different organs, including the brain, eyes, heart, lungs, and skin. Around 3-4% of children with autistic disorder also have tuberous sclerosis. For further info: Tuberous Sclerosis Alliance

Mayo Clinic
Screening and Diagnosis
Your child's doctor will look for signs of developmental delays at regular checkups. If your child shows some signs of autism, you may be referred to a specialist in treating children with autism. This specialist, working with a team of professionals, can perform a formal evaluation for the disorder.

Because autism varies widely in severity and manifestations, making a diagnosis may be difficult. There isn't a medical test to pinpoint the disorder. Instead, a formal evaluation consists of observing your child and talking to you about how your child's social skills, language skills and behavior have developed and changed over time. To help reach a diagnosis, your child may undergo a number of developmental tests covering speech, language and psychological issues.

Although the signs of autism often appear by 18 months, the diagnosis sometimes isn't made until age 2 or 3, when there may be more obvious delays in language development. Early diagnosis is important because early intervention — preferably before age 3 — seems to be associated with the best chance for significant improvement.