The National Institute of Child Health and HumanDevelopment (NICHD), part of the National Institutes ofHealth (NIH), within the U.S. Department of Health andHuman Services, is one of many federal agencies doing researchon autism, including its possible causes.

In 1997, the NICHD and the National Institute on Deafnessand Other Communications Disorders (NIDCD) started theNetwork on the Neurobiology and Genetics of Autism:Collaborative Programs of Excellence in Autism (CPEA).Researchers in this Network work to understand which genesmight be involved in autism and how genes play a role in thecondition. Working with other scientists around the world, theCPEA researchers have already learned a great deal aboutautism and genes.

What are genes?

Genes are pieces of DNA, materialthat contains all the informationneeded to “build” a person. Genesare hereditary, meaning parents passgenes on to their children.

Most genetic material is found in thenucleus of a cell, a storage area thatkeeps these materials together in one place. The nucleus storesgenetic materials in packages called chromosomes. Most peoplehave 46 chromosomes in most of their cells: 23 from theirmother and 23 from their father. Each chromosome is made upof genes.

Genes contain the information your body uses to makeproteins, the body’s building blocks. Proteins make up thestructure of your organs and tissues; they are also needed forthe body’s chemical functions and pathways. Each proteinperforms a specific job in the body’s different types of cells, andthe information for making at least one protein is contained in asingle gene.

N I C H D

National Instituteof Child Health and Human Development

National Institutes of Health

www.nichd.nih.gov

AutismResearch atthe NICHD

Autism and Genes

U.S. DE PA R T M E N T O F HE A LT HA N D HU M A N SE RV I C E SNational Institutes of Health

Check the Glossaryon pages 9-11 to

learn how to say the boldedwords and what

they mean.

AUTISM RESEARCH AT THE NICHD

The pattern or sequence of your genes is like ablueprint that tells your body how to build itsdifferent parts. For example, your genes controlhow tall you are, what color your eyes and hairare, and other features of your body and mind.Changes, or mutations in the blueprint canchange how the body or mind grows/develops.

What is autism?

Autism is a complex neurobiological disorder ofdevelopment that lasts throughout a person’s life.It is sometimes called a developmental disabilitybecause it usually starts before age three, in thedevelopmental period, and because it causesdelays or problems in many different skills thatarise from infancy to adulthood.

The main signs and symptoms of autisminvolve1 language, social behavior, and behaviorsconcerning objects and routines:

! Communication—both verbal (spoken) andnon-verbal (unspoken, such as pointing, eyecontact, or smiling)

! Social interactions—such as sharing emotions,understanding how others think and feel(sometimes called empathy), and holding aconversation, as well as the amount of time aperson spends interacting with others

! Routines or repetitive behaviors—often calledstereotyped behaviors, such as repeating wordsor actions over and over, obsessively followingroutines or schedules, playing with toys orobjects in repetitive and sometimesinappropriate ways, or having very specific andinflexible ways of arranging items

People with autism might have problems talkingwith you, or they might not want to look you inthe eye when you talk to them. They may haveto line up their pencils before they can payattention, or they may say the same sentenceagain and again to calm themselves down. Theymay flap their arms to tell you they are happy, orthey might hurt themselves to tell you they arenot. Some people with autism never learn howto talk.

These behaviors not only make life difficult forpeople who have autism, but also take a toll ontheir families, their health care providers, theirteachers, and anyone who comes in contact withthem.

Because different people with autism can havevery different features or symptoms, health careproviders think of autism as a “spectrum”disorder—a group of disorders with a range ofsimilar features. Based on their specific strengthsand weaknesses, people with autism spectrumdisorders (ASDs) may have mild symptoms ormore serious symptoms, but they all have anASD. This fact sheet uses the terms “ASD” and“autism” to mean the same thing.

What causes autism?

Scientists don’t know exactly what causes autism.

Much evidence supports the idea that geneticfactors—that is, genes, their function, and theirinteractions—are one of the main underlyingcauses of ASDs. But, researchers aren’t lookingfor just one gene. Current evidence suggeststhat as many as 12 or more genes on differentchromosomes may be involved in autism todifferent degrees.

2

AUTISM AND GENES

Some genes may place a person at greater riskfor autism, called susceptibility. Other genesmay cause specific symptoms or determine howsevere those symptoms are. Or, genes withmutations might add to the symptoms of autismbecause the genes or gene products aren’tworking properly.

Research has also shown that environmentalfactors, such as viruses, may also play a role inautism.

While some researchers are examining genes andenvironmental factors, other researchers arelooking at possible neurological, infectious,metabolic, and immunologic factors that may beinvolved in autism.

Because the disorder is so complex, and becauseno two people with autism are exactly alike,autism is probably the result of many causes.

Why study genes to learnabout autism?

Past research links autism and genes. Forexample:

! Studies of twins with autism—Scientists havestudied autism in both identical twins—whoare genetically the same—and fraternaltwins—who are genetically similar, but not thesame. When identical twins have autism, bothhave autism more than 60 percent1 of thetime, depending on the criteria used. Whenfraternal twins have autism, both have autismbetween 0 percent2 and 6 percent of the time.If genes were not involved in autism, the rateof autism would be the same for both types oftwins.

! Family studies of autism—Studies of familyhistories show that the chances a brother orsister of someone who has autism will alsohave autism is between 2 percent and 8 percent3, which is much higher than in thegeneral population. Also, some of the autism-like symptoms, such as delays in languagedevelopment, occur more often4 in parentsand adult brothers and sisters of people withautism than in families who have no membersor relatives with ASDs. Because members ofthe same family are more likely to share genes,something about these genes’ sequencesappears to be related to autism.

! Diagnosable disorders and autism—In about 5 percent5 of autism cases, another single-genedisorder, chromosome disorder, ordevelopmental disorder is also present. Thistype of co-occurrence helps researchers whoare trying to pinpoint the genes involved inautism. Similar disorders or conditions withsimilar symptoms may have similar geneticbeginnings. In cases of one disordercommonly occurring with another, it could bethat one is actually a risk factor for the other.This kind of information can provide clues towhat actually happens in autism. For example,many people with ASDs also have epilepsy, acondition marked by seizures. If scientistscan understand what happens in epilepsy, theymay also find clues to what happens in autism.

Based on these and other findings, scientistshave long felt that there was a likely link betweengenes and autism.

3

AUTISM RESEARCH AT THE NICHD

But, how symptoms of ASDs affect familymembers and the wide variety of symptoms inASDs tell researchers that they aren’t looking forjust one gene. So, even when scientists find thegenes involved in autism, their work will be justbeginning. They will still have to uncover whatroles the genes play in the condition.

How do researchers look forthe genes involved in autism?

Scientists generally use a combination ofmethods to find candidate genes—genes likelyto be involved in autism.

Screen the whole genome.

A genome is all the genetic material in a person’scells—their DNA, their genes, and theirchromosomes. Usually, researchers screen thegenome of a family or a set of families that hasmore than one member with an ASD, to look forcommon features and differences. They look forso-called links between those diagnosed withASDs and the genes within these families. Using“marker” locations—genes whose position in thegenome is known—researchers can narrow downthe location of genes involved in ASD. If agene involved with autism is close to a particularmarker, scientists can identify this gene bymapping it in relation to the known markers.

Conduct cytogenetic studies.

In a cytogenetic study, researchers stainchromosomes with a dye and then look at themunder a microscope. The dye creates light anddark bands that are unique to each chromosome.Researchers compare the resulting bands of two

people with autism, of one person with autismand one relative, or of one person with autismand one person not affected by ASD. Thesecomparisons can point out similarities anddifferences between regions on the chromosome,which researchers can then study further basedon the traits of that specific region.

Examine linkage ratios.

Researchers use this approach to to find hotspots—areas on chromosomes that may containgenes involved in autism. Hot spots are likeneighborhoods on the chromosome where thegenes involved in autism might “reside.” Inmany cases, genes in the same area of achromosome are tightly connected to oneanother, and this connection is hard to break. Ifthe connection is present in more people thanyou might expect by chance, the situation iscalled linkage disequilibrium. Linkagedisequilibrium helps researchers narrow theirgenetic search to find the spot in thechromosomal neighborhood where the genemight be.

Evaluate genes based on their known functions.

In some cases, researchers already know what thenormal function of a specific gene or genes is.If that specific function is abnormal orincomplete in autism, researchers can look at thegenes controlling that function in a person withautism to see what is different or missing. Or,they can look at what kinds of medications areuseful in correcting or controlling that functionto reduce the symptoms of autism. They canthen study the chemical pathways that thesemedications effect to see what step might be

4

AUTISM AND GENES

changed or missing in autism. Once they’vefound the pathway or the change, they can lookat the genes that control these features for moreinformation about autism. This approach isknown as genetic association analysis.

What have researchers found by studying genes and autism?

Researchers in the CPEA Network and theircolleagues around the world have learned a lotabout autism through genetic studies, but theystill have a great deal to learn. To date, some oftheir findings include the following.

Chromosomes where important genes are likely to be found

Using genome-wide screens, scientists haveidentified a number of genes that might beinvolved in autism. Although some analysessuggest that as many as 12 genes6 might beinvolved in ASDs, the strongest evidence7,13

points to areas on:

! Chromosome 2—Scientists know7,10,11,12 thatareas of chromosome 2 are the neighborhoodsfor “homeobox” or HOX genes, the group ofgenes that control growth and developmentvery early in life. You have 38 different HOXgenes in your chromosomal neighborhoods,and each one directs the action of other genesin building your body and body systems.Expression of these HOX genes is critical tobuilding the brain stem and the cerebellum,two areas of the brain where functions aredisrupted in ASDs.

! Chromosome 7—Researchers have found6,7,8,9

a very strong link between this chromosomeand autism. Their investigations now focus ona region called AUTS1, which is very likelyassociated with autism. Most of the genomestudies completed to date have found thatAUTS1 plays some role in autism. There isevidence that a region of chromosome 7 isalso related to speech and language disorders.Because ASDs affect these functions, autismmay involve this chromosome.

! Chromosome 13—In one study, 35 percent7,9

of families tested showed linkage forchromosome 13. Researchers are now tryingto replicate these findings with otherpopulations of families affected by autism.

! Chromosome 15—Genome-wide screens andcytogenetic studies show that a part of thischromosome may play a role in autism.Genetic errors on this chromosome causeAngelman syndrome and Prader-Willisyndrome, both of which share behavioralsymptoms with autism. Cytogenetic errors onchromosome 15 occur9 in up to 4 percent ofpatients with autism.

! Chromosome 16—Genes found on thischromosome control a wide variety offunctions7 that, if disrupted, cause problemsthat are similar or related to symptoms ofautism. For example, a genetic error on thischromosome causes tuberous sclerosis, adisorder that shares many symptoms withautism, including seizures. So, regions on thischromosome may be responsible for certainsimilar behavioral aspects of the two disorders.

5

AUTISM RESEARCH AT THE NICHD

! Chromosome 17—A recent study found thestrongest evidence13 of linkage on thischromosome among a set of more than 500families whose male members were diagnosedwith autism. Missing or disrupted genes onthis chromosome can cause problems, such asgalactosemia, a metabolic disorder that, if leftuntreated, can result in mental retardation.Chromosome 17 also contains the gene for theserotonin transporter, which allows nerve cellsto collect serotonin. Serotonin is involved inemotions and helps nerve cells communicate.Problems with the serotonin transporter cancause obsessive-compulsive disorder (OCD),which is marked by recurrent, unwantedthoughts (obsessions) and/or repetitivebehaviors (compulsions).

! The X chromosome—Two disorders that sharesymptoms with autism—Fragile X syndromeand Rett syndrome—are typically caused bygenes on the X chromosome, which suggeststhat genes on the X chromosome may alsoplay a role in ASDs. People generally have46 chromosomes in most of their cells—23 from their mother and 23 from their father.After fertilization, the two sets match up toform 23 pairs of chromosomes. Thechromosomes in the 23rd pair are called the“sex chromosomes,” X and Y. Theircombination determines a person’s sex—malesusually have one X and one Y chromosome,and females usually have two X chromosomes.The fact that more males than females haveautism supports5,9 the idea that the disorderinvolves genes on the X chromosome.Females may be able to use their other Xchromosome to function normally, whilemales, without such a “back up” showsymptoms of the condition.

Potential candidate genes

By focusing their studies on hot spots,researchers have narrowed their search forcandidate genes. They need to do more work tounderstand how many genes are involved, andhow these genes interact with each other andwith the environment to cause autism.Researchers do have some promising leads—more leads than can be mentioned in this factsheet, but these are a few.

Researchers have found evidence that autismmay involve the HOXA1 gene. HOXA1, ahomeobox gene, plays a critical role in thedevelopment of important brain structures,cranial nerves, the ear, and the skeleton of thehead and neck. Researchers know that theHOXA1 gene is active very early in life—between the 20th and 24th days afterconception—and that any problem with thegene’s function causes problems with thedevelopment of these structures. Such problemsmay contribute to the features of autism.

In one study10, nearly 40 percent of the personswith autism carried a specific mutation in theHOXA1 gene sequence—nearly twice as manyas those who had the same change, but who didnot have autism and were not related to anyonewith autism. In addition, 33 percent of thosewho did not have autism but were related tosomeone with autism also had the mutation intheir HOXA1 gene. These findings mean thatautism does not result from genetics alone, butthat some other factors are also involved incausing the condition. If researchers canconfirm an association between this mutationand ASDs, they may be able to detect themutation as an early test for autism, allowingimportant interventions to start as early in life aspossible.

6

AUTISM AND GENES

Another study11 found that increased head sizein ASD patients was associated with a differentmutation in the HOXA1 gene. About 20percent of persons with autism have large headsize. It is one of the most consistently reportedphysical features of persons with autism. Nowresearchers want to know whether the mutationaffects head size in persons with autism only, orif it affects head size in general, regardless ofASD status.

Several other genes have come forward aspotential candidates, including:

! The Reelin (RELN) gene on chromosome 7 —This gene plays a crucial role in thedevelopment of connections between cells ofthe nervous system. Researchers think thatabnormal brain connectivity plays a role inautism, which makes Reelin a good candidate.In addition, persons with autism and theirparents and siblings have lower levels ofcertain types of the Reelin protein, which maymean that gene is not functioning normally.

! The HOXD1 gene—This homeobox gene iscritical to the formation of certain brainstructures. This gene is involved in Duanesyndrome, a disorder that causes eye-movement problems and sometimes occurswith autism. In one study12 of persons withautism, nearly 94 percent of participants hadmutations in the same regions of HOXD1,which could mean that the region contributesto ASDs.

! Gamma-amino-butyric acid (GABA) pathway genes—GABA compounds areneurotransmitters, which means they helpparts of the nervous system communicatewith each other. GABA receptor genes areinvolved in early development of parts of thenervous system and help with communicationbetween these parts throughout life. Aproblem in the GABA pathway can causesome of the symptoms of ASDs. Forinstance, epilepsy may result, in part, from lowlevels of GABA compounds. Many personswith autism also have epilepsy and also showlow levels of GABA. Current researchfocuses on genes that, when their structure orfunction is incorrect, cause autism-likeproblems in mice.

! Serotonin transporter gene on chromosome 17—The serotonin transporter allows nerve cells tocollect serotonin so that they cancommunicate. Serotonin is a neurotransmitterinvolved in depression, alcoholism/problemdrinking, OCD, and other disorders. Researchshows that persons with autism have higher-than-normal levels of serotonin—rangingbetween 25 percent and 50 percent9,13 higherthan persons without autism. This higherserotonin level may result from problems withthe serotonin transporter that arise from errorsin the gene.

7

AUTISM RESEARCH AT THE NICHD

8

Body chemicals that may play a role in autism

The body makes many chemicals that help itfunction correctly. When these chemicals aremissing or incorrect, the body may haveproblems functioning properly, which may resultin symptoms of autism or other disorders.Researchers are now trying to uncover how bodychemicals might be involved in autism, so theycan learn how the genes that make thesechemicals might also play a role. Researchers arealso studying whether medications might regulateor control these chemicals to create normalchemical levels. Normalizing the chemicals in aperson with ASDs might reduce symptoms.

As mentioned earlier, GABA may play a role inautism and definitely plays a role in epilepsy.Levels of different types of GABA compoundsare abnormally low in persons with autism.Researchers believe that these low levels maycontribute to autism. In studies of mice,disrupting the GABA pathway causes seizures,extreme reactions to touch and sound, andstereotyped actions—symptoms also common inautism. Research now focuses on whethermedications used to treat these problems canalso reduce some of the symptoms of autism.

Another brain chemical mentioned earlier—serotonin—is also out-of-balance in manypersons with autism. High serotonin levels mayexplain why persons with autism have problemsshowing emotion and handling sensoryinformation, such as sounds, touch, and smells.Researchers now focus on whether medicationsthat regulate serotonin levels may improvebehavior in persons with autism. They alsoexamine the genes that make and regulateserotonin and its pathway components to see ifthey can find any changes or patterns.

What does the future hold forstudies of genes and autism?

Scientists in the CPEA Network and theircolleagues who study the genetic mechanisms ofautism hope that these studies will reveal themain cause or causes of autism. Doctors couldthen test for the gene or genes to detect autismearly in life so that intervention can begin whenit is most effective. Or, researchers coulddevelop drugs that change or regulate the geneor genes to help normalize body chemicals andbody functions.

Researchers share their information and theirmethods to see if other researchers can replicatetheir findings. Having several scientists get thesame results “confirms” that discovery. Onceconfirmed, a discovery becomes the steppingstone to other discoveries. To date, however, notall genetic studies have gotten the same results.Therefore, additional work is still important.

Scientists also look beyond genes to find factorsthat may play a role in autism, including things inthe environment. Environmental features canaffect how genes function, which may contributeto the symptoms of ASDs. By understandinggenetic and environmental causes of autism,scientists may better understand how to treat itand maybe even how to prevent it. Doctors andscientists continue to study genes, theenvironment, and gene-environment interactionsuntil they solve the mysteries of autism.

AUTISM AND GENES

9

Glossary

The word… Is pronounced… And means…Angelman syndrome Ayn-JELL-mann

sinn-DROMA genetic disorder caused by abnormal function of thegene UBE3A, located within a small region onchromosome 15. Characteristics include:developmental delay, lack of speech or minimal use ofwords; movement or balance disorder, usually ataxia ofgait and/or tremulous movement of limbs, and anycombination of frequent laughter/smiling; apparenthappy demeanor; easily excitable personality, often withhand flapping movements; hypermotoric behavior; shortattention span.

Candidate gene kan-di-DATE jeen

A gene, located in a chromosome region suspected ofbeing involved in a disorder, whose protein productsuggests that it could be the gene in question.

Chromosome kro-mu-SOM One of the "packages" of genes and other DNA in thenucleus of a cell. Humans have 23 chromosome pairs,46 in all. Each parent contributes one chromosome toeach pair, so children get half of their chromosomesfrom their mothers and half from their fathers.

Cytogenetic sigh-TOW-jenn-eh-tik Study of chromosomes using a specific method thatinvolves staining a chromosome and examining it undera microscope.

Duane syndrome DWAYNE sinn-DROM

An inherited disorder characterized by inability of one orboth eyes to turn outward beyond the midline. In somecases there is also a deficit of inward motility of the eye(turning toward the nose).

Epilepsy epp-ih-LEPP-see A brain disorder in which clusters of nerve cells, orneurons, in the brain sometimes signal abnormally. Inepilepsy, the normal pattern of neuronal activitybecomes disturbed, causing strange sensations,emotions, and behavior or sometimes convulsions,muscle spasms, and loss of consciousness.

Fragile X syndrome FRA-jell EKS sinn-DROM

The most common form of inherited mental retardation.A mutation in a single gene, the FMR1 gene on the Xchromosome, causes the disorder, which can be passedfrom one generation to the next. Symptoms occurbecause the mutated gene cannot produce enough of aprotein that is needed by the body’s cells, especiallycells in the brain, to develop and function normally.

Fraternal twins frah-TURN-ul twinns

Twins resulting from the fertilization of two separateeggs. Fraternal twins share about 50 percent of theirgenes, just like siblings who are born at different times.

Galactosemia guh-lak-toe-SEE-mee-uh

A rare disorder in which the body cannot process thesugar galactose, a by-product of milk metabolism.Buildup of galactose “poisons” the body, causing liver,kidney, and eye damage, and even death (if untreated).

AUTISM RESEARCH AT THE NICHD

10

Glossary (Continued)

The word… Is pronounced… And means…

Gene jeen Pieces of DNA. They contain the information formaking a specific protein.

Genome JEE-nom All the DNA contained in an organism or a cell; includesboth the DNA and chromosomes within the nucleus andthe DNA outside the nucleus.

Hereditary ha-RED-ih-tarry A gene or trait passed down from parent to offspring.

Homeobox genes HOE-mee-oh-boksjeenz

Genes found in almost all animals that control how andwhere parts of the body develop. Active very early inlife, acting like a movie director by telling other geneswhen to act and when to stop in building the body.

Hot spots hot spotz Areas on chromosomes where mutations, activity, orrecombination occurs with unusually high frequency.

Identical twins eye-DEN-tik-ul twinns

Twins formed from the splitting of the same fertilizedegg, so they share 100 percent of their genetic material.

Linkagedisequilibrium

LINK-aj DISS-ee-kwel-ih-bree-um

An association of genes and/or markers near eachother on a chromosome that is more than would beexpected by chance. Linked genes and markers tend tobe inherited together.

Mutation my-TAH-shun A permanent structural change in DNA. In most cases,DNA changes either have no effect or cause harm, butsome mutations improve an organism's survival.

Neurotransmitter nyur-OH-tranz-mitt-er A substance that transmits nerve impulses betweennerve cells.

Nucleus NOO-klee-us The central cell structure that houses chromosomes.

Obsessive-compulsive disorder (OCD)

ahb-SESS-ivkum-PUL-shenDISS-or-dr

A disorder characterized by recurrent, unwantedthoughts (obsessions) and/or repetitive behaviors or anurgent need to perform “rituals” (compulsions).

Prader-Willisyndrome

PRAY-derr WILL-eesinn-DROM

An uncommon inherited disorder characterized bymental retardation, decreased muscle tone, shortstature, emotional liability, and an insatiable appetitethat can lead to life-threatening obesity. Caused by amissing part on the paternally derived chromosome 15.

Protein PRO-teen A large molecule made up of one or more chains ofamino acids. Proteins perform a wide variety of activitiesin the cell and in the body.

Replicate repp-li-KATE Describes a situation in which many studies that use thesame methods and steps have gotten the sameoutcome, suggesting that a finding is likely to be true.

Rett syndrome RETTsinn-DROM

Results mostly from mutations in the MECP2 gene onthe X chromosome and occurs almost exclusively ingirls. After seemingly normal development, affected girlsdevelop problems with language, learning, coordination,and other brain functions.

AUTISM AND GENES

11

References1. Folstein & Rutter, 1977; Bailey, et al, 1995; Smalley, et al,

1988, as cited in Ingram, 2000.

2. Steffenburg, et al, 1989, as cited in Muhle, 2004.

3. Gillberg, et al, 2000; Chakrabarti, et al, 2001; Chudley, etal, 1998, as cited in Muhle 2004.

4. Landa, et al, 1991; Landa, et al, 1992; Volkmar, et al,1998; MacLean, et al, 1999, as cited in Ingram, 2000.

5. Gillberg. (1998). Chromosomal disorders and autism.Journal of Autism and Developmental Disorders, 28:415-425.

6. IMGSAC. (1998). A full genome screen for autism withevidence for linkage to a region of chromosome 7q.Human Molecular Genetics, 7:571-578

7. Collaborative Linkage Study of Autism (1999). Anautosomal genomic screen for autism. American Journal ofMedical Genetics, 88:609-615; and International MolecularGenetic Study of Autism Consortium (2001). Agenomewide screen for autism: Strong evidence forlinkage to chromosomes 2q, 7q, and 16p. AmericanJournal of Human Genetics, 69:570-581.

8. IMGSAC. (2001). Further characterization of autismsusceptibility locus AUTS1 on chromosome 7q.Human Molecular Genetics, 10(9):973-982.

9. Muhle, et al. (2004). The Genetics of Autism. Pediatrics,113(5): e472-e486.

10. Ingram JL, Stodgell CJ, Hyman SL, Figlewicz DA,Weitkamp LR, and Rodier PM. (2000). Discovery ofallelic variants of HOXA1 and HOXB1: geneticsusceptibility to autism spectrum disorders. Teratology,62:393-405.

11. Conciatori, et al. (2004). Association between theHOXA1 A218G polymorphism and increased headcircumference in patients with autism. Journal ofBiological Psychiatry, 55: 413-419.

12. Stodgell, et al. (2004). Association of HOXD1 andGBX2 allelic variants with autism spectrum disorders.Presented at the CPEA/STAART Annual ScientificMeeting.

13. Cantor, et al. (2005). Replication of autism linkage:Fine mapping peak at 17q21. American Journal of HumanGenetics, 76: 1050-1056.

The NICHD would like to thank Fred Volkmar,M.D., and Ed Cook, M.D., for their assistance onthis fact sheet.

Glossary (Continued)

The word… Is pronounced… And means…

Seizure SEE-jyur A sudden attack, often one of convulsions, as inepilepsy. Seizures don’t necessarily involve movementor thrashing; they can also make someone seem asthough they are frozen, unmoving.

Serotonin serr-oh-TOE-ninn A neurotransmitter that is found especially in the brain,blood serum, and stomach lining of mammals.

Stereotyped STARE-ee-oh-tipd An action that is repeated without change.

Susceptibility suss-ept-ih-BULL The state of being predisposed to, sensitive to, or oflacking the ability to resist manifestations of something(such as a pathogen, familial disease, or a drug); aperson who is susceptible is more likely to showsymptoms of a disorder.

Tuberous sclerosis TOOB-er-us sklar-OH-siss

A rare, multi-system genetic disease that causes non-cancerous tumors to grow in the brain and on other vitalorgans such as the kidneys, heart, eyes, lungs, andskin. It commonly affects the central nervous systemand results in a combination of symptoms includingseizures, developmental delay, behavioral problems,skin abnormalities, and kidney disease.

How can I get involved with studies of autism?

If you are interested in taking part in one of the CPEA studies, or if you want more information aboutone of the CPEA sites, visit http://www.nichd.nih.gov/autism/cpea.cfm. You and your family arewelcome to take part in many different studies, but you can only take part in one genetics study at atime.

To find out what studies related to autism are currently looking for participants, go tohttp://www.nichd.nih.gov/autism/research.cfm and choose the “Autism clinical trials currently recruitingpatients” link.

You can also visit http://www.clinicaltrials.gov or call 1-800-411-1222 for more information on federallyfunded studies that are seeking participants.

AUTISM RESEARCH AT THE NICHD

Where can I go for more information about genes and autism?

For more information about the CPEA Network, genetic studies, or autism re s e a rc h ,contact the NICHD. The NICHD supports and conducts re s e a rch on topics related to thehealth of children, adults, families, and populations, including autism and developmentaldisabilities. The mission of the NICHD is to ensure that every person is born healthy andwanted, that women suffer no harmful effects from the re p roductive process, and that allc h i l d ren have the chance to fulfill their potential for a healthy and productive life, free ofdisease or disability, and to ensure the health, pro d u c t i v i t y, independence, and well-beingof all people through optimal rehabilitation. You can contact the NICHD through the NICHD Information Resource Center a t :

M a i l : P.O. Box 3006, Rockville, MD 20847Phone: 1-800-370-2943 (TTY: 1-888-320-6942)F a x : (301) 984-1473E - m a i l : N I C H D I n f o rm a t i o n R e s o u rceCenter@mail.nih.gov (Please use AUTISM in the subject line)I n t e rn e t : h t t p : / / w w w. n i c h d . n i h . g o v / a u t i s m

The National Library of Medicine also provides information on ASDs athttp://www.nlm.nih.gov/medlineplus/autism.html. The NIH Web site also has informationabout ASDs at http://health.nih.gov/result.asp/62.

12

AUTISM RESEARCH AT THE NICHD

NIH Pub. No. 05-5590May 2005