A novel missense LIPA gene mutation, N98S, in a patient with cholesteryl ester storage disease

Lysosomal acid lipase plays an important role in maintaining cellular cholesterol homeostasis. Complete absence of lysosomal acid lipase activity results in Wolman disease and usually death in infancy, whereas partial deficiency of lysosomal acid lipase results in cholesteryl ester storage disease (CESD). We describe a 26 year-old female with CESD who presented with recurrent right upper quadrant abdominal pain. Abnormal liver function tests and a subsequent liver biopsy revealed features consistent with CESD. Sequencing of the LIPA gene revealed that she was a compound heterozygote for the previously reported exon 8 splice junction mutation and a novel missense mutation (N98S) in exon 4. The splice junction mutation allows some (approximately 3%) normal splicing to occur, and therefore gives rise to residual lysosomal acid lipase activity. Asn98 in lysosomal acid lipase is highly conserved among species and mutation of this residue could influence catalytic activity or accessibility to the active site. In summary, we describe a CESD patient compound heterozygous for the LIPA exon 8 splice junction mutation and a novel missense mutation, N98S.