SMA TYPE-2 UNRELATED TO CHROMOSOME 5Q13

We describe two brothers with clinical and histological findings of ty pe 2 spinal muscular atrophy (SMA) associated with small head circumfe rence (<2%) and normal cognitive development. No survival motor neuron (SMN) or neuronal apoptosis-inhibitory protein (NAIP) deletions were detected in these sibs, and they were discordant for the haplotypes de termined by DNA markers flanking the 5q13 SMA locus, These findings su pport the presence of a distinct anterior horn disease unrelated to 5q 13. This entity may have either autosomal recessive or X-linked inheri tance. (C) 1998 Wiley-Liss, Inc.