Identification of a CTL4/Neu1 Fusion Transcript in a Sialidosis Patient

The deficiency of the lysosomal neuraminidase (NEU1; sialidase) causes the storage disorder sialidosis with symptoms ranging from eye abnormalities and neurological disturbances to skeletal malformations, mental retardation and early death. Sialidosis patients encompassing a wide spectrum of clinical symptoms were screened for mutations in neu1. We identified the same homozygous interstitial deletion (11 kb) in two patients causing the fusion of exon 10 of CTL4 (New Gene 22; NG22) with the 3'-UTR of neu1. In one patient we found the resulting CTL4/Neu1 fusion transcript, in the other we detected an alternatively spliced CTL4 transcript (retention of intron 9).