Autism genetic meta-analysis: Chromosomes 2, 7, and 15

The search for the cause of autism spectrum disorders (ASD) has lead to much investigation into genetic associations. Studies have typically examined relatively small sample sizes across various sets of genes thought to be associated with ASD. The heterogeneity implicit in ASD typically complicates the search.

A meta-analysis was conducted on genetic linkage studies (LOD scores) in ASD for the years 2000–2006 on chromosomes 2, 7, and 15. LOD scores were examined to develop an overall meta-analysis of linkages across regions of the selected chromosomes. Results for chromosome 2 show the greatest evidence for a possible linkage to autism. 14% had LOD scores > 1.5, and 6.6% > 2.0. Many of the results were from similar regions on chromosome 2, five within the 240 – 270 centimorgan region and four within 173 – 186. Two markers, D2S1397 and D2S2188, exceeded an LOD score of 3.0, the generally accepted threshold to indicate genetic linkage, with LOD scores of 4.03 and 3.74 respectively. Results for chromosome 7 had a high percentage of LOD scores > 1.5 and > 2.0, 19.15% and 14.9% respectively. Two pairs of significant markers came from similar regions; 104 – 109 centimorgans and 152 – 165. Markers D7S477 and D7S2195 had LOD scores of 3.2 and 1.65 respectively. Chromosome 15 showed the least evidence for linkage to autism with no LOD scores > 1.5.

While a genetic basis of ASD is accepted, identifying specific genes are chromosome regions remains a challenge.