A patient with Smith–Lemli–Opitz syndrome: novel mutation of the DHCR7 gene and effects of therapy with simvastatin and cholesterol supplement

Background The Smith–Lemli–Opitz (SLO) syndrome is a multiple congenital anomaly with mental retardation due to a decreased or lack of activity of 7-dehydrocholesterol reductase as a consequence of mutations of the DHCR7 gene. This paper describes a special patient with SLO syndrome. Laboratory examination showed low cholesterol (2.77 mmol/L) and increased 7-dehydrocholesterol level (102 mg/L). Molecular genetic analysis revealed a compound heterozygosity c.964-1G>C/p.G366V (c.G1370T) of the proband. The p.G366V is a novel mutation of the DHCR7 gene with guanine by thymine nucleotide exchange resulting in glycin by valin amino acid exchange in the dehydrocholesterol reductase enzyme. Simvastatin (0.2 mg/kg/day) and cholesterol replacement therapy (150–250 mg/kg/day) led to significant improvement in the patient's laboratory findings (7-dehydrocholesterol, cholesterol) as well as in his behavior and gross motor function.