The unique population history of the Northern Finland Intellectual Disability (NFID) cohort makes the identification of recessive variation somewhat more likely while reducing overall genetic heterogeneity.
Sampling is population-based (N=900) with 18% profound, 29% moderate, and 53% mild ID (53% with a family history of ID). Of cases: 18% autism spectrum disorders, 8% ADHD symptoms, and 14% other major psychiatric diagnoses including childhood-onset schizophrenia. Preliminary results from exome sequencing on 900 ID cases show enrichment for rare deleterious variants (recessive and some dominant), similar to our work on the TOP3B CNV. Clinical evaluation of ID cases includes cognitive testing, karyotyping, metabolic screens, GWA/CNVs, exome sequencing, and genome sequencing for trios. All subjects are consented for re-contact and iPSC sampling.