Spectrin mutations in hereditary elliptocytosis and hereditary spherocytosis.

ABSTRACT

Hereditary elliptocytosis (HE), its aggravated form hereditary pyropoikilocytosis (HPP), and hereditary spherocytosis (HS) designate a set of congenital hemolytic syndromes. The responsible mutations lie in several genes encoding proteins of the red cell membrane. In particular, they involve the SPTA1 and SPTB genes that encode erythroid spectrin alpha- and beta-chains, respectively. In situ, spectrin is a alpha 2 beta 2 fibrillar tetramer resulting from the head-to-head self-association of two alpha beta dimers. In HE, the 24 known alpha-chain mutations lie in the self-association site or its vicinity, whereas the 17 beta-chain mutations occur in the self-association site itself (record of November 30, 1995). Allele alpha LELY (LELY Low Expression LYon) is found in ethnic groups remote from one another with a uniform frequency (20-30% of all alpha-alleles). It allows an expanded expression of any HE alpha-allele located in trans and results in severe HE or in HPP. In HS, a number of spectrin mutations have been recorded recently. Allele alpha LEPRA (LEPRA Low Expression PRAgue) would occur in a recurrent fashion.