Homozygous missense mutation in the ECM1 gene in Chinese siblings with lipoid proteinosis.

Lipoid proteinosis is caused by loss-of-function mutations in the glycoprotein extracellular matrix protein 1 (ECM1). We report here mutation analysis of the ECM1 gene in a Chinese family with lipoid proteinosis. A 10-year-old boy presented with a hoarse voice, acneiform scars and yellow skin nodules, as well as beaded eyelid papules and a thickened sublingual frenulum. Skin biopsy showed widespread deposition of hyaline material in the dermis and thickened basement membrane. His elder sister had the same clinical manifestations. The coding region of ECM1 was amplified and sequenced and both affected siblings were shown to have a novel homozygous single nucleotide substitution, c.658T>G, in exon 6, which converts cysteine to glycine, designated p.C220G. Both parents were heterozygous for this mutation which was not detected in 100 control chromosomes. Missense mutations in the ECM1 gene are an unusual finding in lipoid proteinosis, but this case adds to the spectrum of disease-associated mutations in this rare genodermatosis.