p.R218X p.Arg218Ter c.652 C>T found in a compound heterozygote with c.894 G>A (S275_Q298del) and R197X in mature protein. Found also in a compound heterozygote with c881T>C, P.L294S
BACKGROUND AND AIMS: Childhood/Adult-onset Lysosomal Acid Lipase Deficiency (LAL-D) is a recessive disorder due to loss of function variants of LAL, the enzyme which hydrolyses cholesteryl esters, derived from internalized apoB containing lipoproteins. The disease is characterized by multi-organ involvement including the liver, spleen, intestine and cardiovascular system. The aim of this study was the clinical and molecular characterization of 14 (13 unrelated) previously unreported patients with childhood-onset LAL-D. METHODS: Data collected included clinical and laboratory investigations, liver imaging, liver biopsy and LIPA gene analysis. The response to lipid-lowering medications, liver transplantation and enzyme replacement therapy (ERT) was reported for some patients. RESULTS: LAL-D was suspected at 4.4 +/- 3.3 years of age for the presence of hepatomegaly, elevated serum transaminases and hypercholesterolemia, and was confirmed by liver biopsy/imaging and LAL assay. The follow up period ranged from 3 to 40 years (mean 7.8 +/- 4.0 years in 13 cases). Patients treated with statins with or without ezetimibe showed 28% reduction of plasma LDL-cholesterol without a tangible effect on liver enzymes; some patients receiving ERT showed normalized lipoprotein profile and transaminase levels. The common c.894G > A variant was observed in homozygosity or compound heterozygosity in 10 patients. We found seven previously reported variants: p.(Trp140*), p.(Arg218*), p.(Gly266*), p.(Thr288Ile), p.(Leu294Ser), p.(His295Tyr) and p.(Gly342Arg) and two novel variants: p.(Asp345Asn), affecting the LAL catalytic triad, and c.229+3A > C, affecting splicing. Homozygosity for p.(Thr288Ile) or c.229+3A > C was associated with a severe phenotype. CONCLUSIONS: This study provides additional data on the features of childhood-onset LAL-D and describes two novel pathogenic variants of the LIPA gene.
Cholesteryl Ester Storage Disease (CESD) is a rare recessive disorder due to mutations in LIPA gene encoding the lysosomal acidic lipase (LAL). CESD patients have liver disease associated with mixed hyperlipidemia and low plasma levels of high-density lipoproteins (HDL). The aim of this study was the molecular characterization of three patients with CESD. LAL activity was measured in blood leukocytes. In two patients (twin sisters) the clinical diagnosis of CESD was made at 9 years of age, following the fortuitous discovery of elevated serum liver enzymes in apparently healthy children. They had mixed hyperlipidemia, hepatosplenomegaly, reduced LAL activity (approximately 5% of control) and heteroalleic mutations in LIPA gene coding sequence: (i) the common c.894 G>A mutation and (ii) a novel nonsense mutation c.652 C>T (p.R218X). The other patient was an 80 year-old female who for several years had been treated with simvastatin because of severe hyperlipidemia associated with low plasma HDL. In this patient the sequence of major candidate genes for monogenic hypercholesterolemia and hypoalphalipoproteinemia was negative. She was found to be a compound heterozygote for two LIPA gene mutations resulting in 5% LAL activity: (i) c.894 G>A and (ii) a novel complex insertion/deletion leading to a premature termination codon at position 82. These findings suggest that, in view of the variable severity of its phenotypic expression, CESD may sometimes be difficult to diagnose, but it should be considered in patients with severe type IIb hyperlipidemia associated with low HDL, mildly elevated serum liver enzymes and hepatomegaly.