DETECTING PORCN MICRODELETIONS IN A LARGE FAMILY WITH FOCAL DERMAL HYPOPLASIA.

Focal dermal hypoplasia (FDH), an X-linked dominant disease with a highly variable phenotype, presents mainly with congenital linear pigmentation of the skin, herniation of fat through the dermal defects and multiple papillomas. PORCNmicrodeletions are identified in a total of 12 FDH patients to date. Routine molecular methods for detecting microdeletions have proven not to be effective, as patients also carry a normal allele. Additionally, methods using copy number estimations are labor-intensive, time-consuming and require expensive equipment. With respect to the molecular diagnosis of FDH, we aimed to investigate the inheritance of maternal disease allele in a three-generation FDH pedigree with seven affected members by using a simple yet efficient method. The strategy used in this study appeared to have the benefit of detecting all PORCN micro-deletions identified for FDH so far. The family with the largest number of related patients reported to date presented an opportunity to evaluate clinical variability, which was high, with the least affected and the most severely affected patients being half-sisters. The extensive intra-familial phenotypic variability observed in this FDH family suggests that genetic counselling should be part of management of this syndrome even in a family with a very mild case. The unique finding of IgA deficiency in the most severe case indicated that the feature could be a new characteristic of FDH.