DNA-based Prenatal Diagnosis of Epidermolytic Palmoplantar Keratoderma in Two Pregnancies at Risk in One large Pedigree

Yang, Jun Mo; Shin, Jang Hyun; Cho, Mi Ook; Bae, Duk Soo; Yang, Soon H; Chung, Jae Hyun; Lee, Joo Heung

Abstract

BACKGROUND
Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant disease of cornification which presents as severe thickening of the palms and soles with prominent epidermolytic hyperkeratosis pathologically. Recent studies have shown that EPPK is caused by mutations in the keratin 9 (K9) gene which is expressed essentially only in the palms and soles. Previously, We have reported that patients in one large pedigree of EPPK have an R162W substitution in the K9 protein. In this pedigree, two women whose husbands are both EPPK patients had become pregnant.
OBJECTIVE
Since both women were concerned about this genetic disorder, we have performed prenatal diagnosis by biopsy analysis of chorionic villi tissue.
METHODS
Chorionic villi biopsies were performed at 12 weeks gestation. Since the skin lesions are strictly confined to the palms and soles of the babies, the prenatal diagnosis of EPPK by ultrastructural analysis of fetal skin biopsy or amniotic fluid cells is highly problematic. Polymerase chain reaction amplification of specific allele (PASA) assay and direct DNA sequencing analyses were performed whether the fetuses carried mutant allele of K9 gene.
RESULTS
PASA assay and direct DNA sequencing analyses showed that one fetus was normal, but the other fetus carried the abnormal allele. Subsequently, the mother of the unaffected fetus delivered a normal child, but the mother of the affected fetus terminated the pregnancy.
CONCLUSION
We describe the analysis of the K9 mutation in the two fetuses at risk for EPPK. We believe that this is the first report of prenatal diagnosis for EPPK. But, we have to think about the ethical problems before we decide to perform the prenatal diagnosis of any kind of skin diseases.