Genetic testing in autism: how much is enough?
OBJECTIVE
To evaluate the yield of genetic testing in children with autism spectrum disorders.


METHODS
We performed a retrospective chart review of 71 unrelated patients with a diagnosis of an isolated autism spectrum disorder seen in a genetics clinic over a period of 14 months. For most, referrals occurred after evaluation by a developmental pediatrician and/or psychologist to establish the diagnosis. Tiered laboratory testing for the majority of the patients followed a guideline that was developed in collaboration with clinicians at The Autism Center at Children's Hospital, Columbus, OH.


RESULTS
The patients included 57 males and 14 females; 57 met DSM-IV criteria for autism, with the rest being Asperger or pervasive developmental disorder not otherwise specified. Macrocephaly [head circumference (HC) >or=95%] was present in 19 (27%). Two children had visible chromosome abnormalities (47,XYY; 48,XY + 2mar/49,XY + 3mar). Two patients with autism and macrocephaly had heterozygous mutations in the PTEN tumor suppressor gene. Three females had Rett syndrome, each confirmed by DNA sequencing of the MECP2 gene. Extensive metabolic testing produced no positive results, nor did fragile X DNA testing.


CONCLUSIONS
The overall diagnostic yield was 10% (7/71). PTEN gene sequencing should be considered in any child with macrocephaly and autism or developmental delay. Metabolic screening may not be warranted in autism spectrum disorders without more specific indications or additional findings.
Herman
Gail E
GE
Center for Molecular and Human Genetics, Columbus Children's Research Institute, Columbus, Ohio 43205, USA. hermang@ccri.net
Henninger
Nathan
N
Ratliff-Schaub
Karen
K
Pastore
Matthew
M
Fitzgerald
Sara
S
McBride
Kim L
KL
D000293:Adolescent; D000596:Amino Acids / Q000097:blood / Q000652:urine; D002508:Cephalometry; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000235:genetics*; D002675:Child, Preschool; D002869:Chromosome Aberrations / Q000706:statistics & numerical data; D005260:Female; D005820:Genetic Testing / Q000379:methods* / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D008297:Male; D051783:Methyl-CpG-Binding Protein 2 / Q000235:genetics; D009820:Ohio; D051059:PTEN Phosphohydrolase / Q000235:genetics; D012189:Retrospective Studies; D017422:Sequence Analysis, DNA
D000596:Amino Acids; C497392:MECP2 protein, human; D051783:Methyl-CpG-Binding Protein 2; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human