Novel donor splice site mutation of ABCG5 gene in sitosterolemia.

In a patient with sitosterolemia, we found two different mutations of the ATP-binding cassette, subfamily G, member 5 (ABCG5) gene. The first is a missense mutation that changes the amino acid residue at position 419 from arginine to histidine, i.e., R419H. The second is a novel splicing mutation affecting the invariant guanine at the first base of the donor splice site of intron 12, i.e., IVS12 + 1G --> A. The father of the patient is heterozygous for the missense mutation, and the mother is heterozygous for the splicing mutation. No mutations were found in the sister of the patient. Up until now, the missense mutation has only been found in Japanese patients with sitosterolemia. We believe that R419H in our Chinese patient may have the same origin as the mutation in the Japanese patients with sitosterolemia.