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Joan Stephenson, PhD

JAMA. 2008;299(11):1252.

	Since this article does not have an abstract, we have provided the first 148 words of the full text and any section headings.

A "microdeletion" on chromosome 15 is associated with a new syndrome characterized by intellectual disability, epilepsy, and facial and digital anomalies, according to an international team of scientists (Sharp AJ. Nat Genet. 10.1038/ng.93 [published online ahead of print February 17, 2008]).

The researchers scanned the genomes of 757 individuals with intellectual disability and/or other congenital anomalies, trawling for chromosomal deletions and duplications. They found a particular microdeletion in 2 unrelated individuals (and later in another 7 persons), an identical 1.5 million base-pair deletion that spanned 6 genes on chromosome 15. One of the missing genes, CHRNA7, encodes a protein involved in nerve cell signaling that previously had been proposed as a possible susceptibility factor for some forms of epilepsy.

The researchers estimated that the microdeletion accounts for about 0.3% of intellectual disability of unknown etiology and has an approximate population incidence of 1/40 000.