Novel and recurrent PORCN gene mutations in almost unilateral and typical focal dermal hypoplasia patients

Abstract

Goltz syndrome or Focal dermal hypoplasia (FDH) is an X-linked dominant disorder characterized by malformations affecting the skin, eyes, central nervous system, and skeletonC:\GetARef\Refs\focal dermal hypoplasia (2007-).re. Mutations in the PORCN gene were identified as the molecular basis of FDH. We report two cases, one caused by a current mutation c.129G>A, which leads to a nonsense mutation W43X, and the other one caused by a novel mutation, c.386delT. The female patient with the recurrent mutation presented with typical cutaneous symptoms and skeletal abnormality, but the female patient with the novel mutation manifested only cutaneous symptoms, with hypo-pigmentation along Blaschko's lines, mainly on her right hemibody. In the latter case, DNA was isolated from peripheral blood cells, lesional skin, and non-lesional skin. The percentage of cells carrying the mutation estimated by subcloning and sequencing of the PCR products was 3.1% in peripheral blood cells, 21% in lesional skin, and 16% in non-lesional skin. X-chromosome inactivation assay showed a slightly skewed pattern in lesional skin, but a random pattern in non-lesional skin and blood. RT-PCR analysis from skin samples showed that PORCN mRNA of the mutated allele had a 13bp nucleotide insertion created by an alternative splicing site. This resulted in abnormal PORCN protein with in-frame insertion of eight amino acids, TTHRGTDD, instead of the original four amino acids, AQMI (126-129). We report a typical FDH patient with a recurrent PORCN mutation, which was previously identified in a male Japanese FDH patient, and a second female, an almost unilateral FDH patient with a postzygotic PORCN mutation.