Evidence for a new microdeletion syndrome in 15q21.

We report on the fourth known case with an interstitial deletion in 15q21. In the present case the breakpoints have been determined by GTG-banding, microdissection and the recently developed multicolor banding (MCB) technique as 15q21.1-q21.3. Common features in all four cases are mental retardation, growth retardation, a beak-like nose with hypoplastic alae nasi and a thin upper lip. Additional frequent features are small hands and feet, hypotonia, low hair implantation, low set ears, clinodactyly and obesity. The possibility that a critical region for a new microdeletion-syndrome is situated in 15q21 is discussed.