A new Cincinnati Children’s Hospital Medical Center study links
regions of two chromosomes to susceptibility for a type of autism
characterized by regression in development. Developmental regression can include the loss of previously acquired language, social skills or both.
Moreover, the study is the first to identify involvement of chromosome 21 in this type of autism. This may explain the increased prevalence of autism spectrum disorders (ASD) among children with Down syndrome, who have an extra copy of chromosome 21 and are 10 times more likely to have an ASD than the general population.
The findings represent “the important first step in identifying
genetic variants that may contribute to susceptibility to this specific type
of ASD,” says Cindy Molloy, M.D., lead author of the study. Dr. Molloy is a
physician at Cincinnati Children’s in the Center for Epidemiology and
Biostatistics and in the division of developmental disabilities.
The study is published in the online edition of the journal Molecular
Psychiatry.
Dr. Molloy and colleagues in the division of human genetics examined a
national database and DNA bank of hundreds of families with ASD. They
identified 32 pairs of siblings, one trio of siblings and one pair of
cousins who showed definite evidence of regression at the age of
approximately 18 to 24 months. They confirmed previous evidence for linkage
with ASD on chromosome 7 and found new evidence for susceptibility on
chromosome 21 in this subset of ASD families. The research team is now
sequencing genes in those regions to find the specific genetic variant that
either contributes to susceptibility or modifies the disease.
“Among children with autism or ASD, 20 to 30 percent have a history of
regression,” says Dr. Molloy. “We think this represents a genetically
distinct subgroup.”
The Autism Society of Greater Cincinnati has just awarded Dr. Molloy a
$40,000 grant to continue this research and extend it to families in the
Cincinnati area.