Two novel mutations in the ABCG5 gene, c.144 -1G>A and c.1523 delC, in a Mexican family with sitosterolemia

- First Mexican family with sitosterolemia.
- Two new ABCG5 gene mutations, c.144 -1G>A and c.1523 delC.
- Two patients, compound heterozygotes, showed phenotypic heterogeneity.

Sitosterolemia is a disease characterized by an intestinal hyperabsorption of plant sterols and cholesterol. Affected individuals have mutations in both alleles of either ABCG5 or ABCG8 genes, leading to a total loss of one of the proteins and subsequent functional deficiency. We here report a Mexican family with clinical and biochemical features of sitosterolemia carrying 2 new mutations of the ABCG5 gene. Concentrations of sitosterol, campesterol, and cholesterol were found to be higher for the index case (a 10-year-old girl) than for her also affected sibling (64.1 vs 19 mg/dL, 32 vs 12.1 mg/dL, and cholesterol 295 vs 235 mg/dL, respectively). Both individuals showed 2 new ABCG5 gene mutations identified by sequencing, which is concordant with their biochemical diagnosis of sitosterolemia. The first mutation was a c.144 -1G>A transition that disrupts the intron 1 splicing acceptor site. The second mutation is the deletion c.1523 delC, which occurred in exon 11, causing an amino acid change at codon 510 (p.His510Thr) and a stop codon at codon 511 (p.Leu511X). The father is heterozygote for the mutation c.144 -1G>A, whereas the mother is heterozygote for the mutation c.1523 delC. In conclusion, we here report the first case of a Mexican family with sitosterolemia carrying two new ABCG5 gene mutations.