Deletions and autism
A recent paper in NEJM is worth a read; it suggests a deletion on chromosome 16 predisposes to autism. The phenotype appears to be highly variable, though:
[I]n a study of the same population by investigators at deCODE Genetics, this deletion was observed at a markedly increased rate in subjects with a psychiatric or language disorder. This study showed that the deletion was present in 1 of 648 patients with schizophrenia, 1 of 420 patients with bipolar disorder, 1 of 203 patients with ADHD (the father of a child with autism, as noted above), and 1 of 3000 patients with panic disorder, anxiety, depression, or addiction. In addition, 1 of 748 patients with dyslexia carried the deletion. Overall, in the Icelandic samples, the carrier frequency among patients with autism was 1%; the frequency was approximately 0.1% among patients with a psychiatric or language disorder and 0.01% in the general population.
All these disease phenotypes can probably be thought of as extremes of some distribution of an underlying trait; I wonder how much variation in the “normal” range can be explained by de novo or rare copy number variants like this one.
I can’t get in the paper, how big is the deletion? The abstract or whatever says microdeletion but those are actually big aren’t they? I didn’t think stamdard autism would be caused by a large deletion (or even just related to, or predisposed by one, or whatever) because the kids look normal don’t they, unlike other kids who have other types of mental retardation caused by deletions (prader willi, VCF, Sharp syndrome), who are usually a little funny looking God bless them.
it’s about half a megabase