Cloning of multiple keratin 16 genes facilitates prenatal diagnosis of pachyonychia congenita type 1.
Pachyonychia congenita type 1 (PC-1) is an autosomal dominant ectodermal dysplasia characterized by severe nail dystrophy, focal non-epidermolytic palmoplantar keratoderma (FNEPPK) and oral lesions. We have previously shown that mutations in keratin K16 cause fragility of specific epithelia resulting in phenotypes of PC-1 or FNEPPK alone. These earlier analyses employed an RT-PCR approach to avoid amplification of K16-like pseudogenes. Here, we have cloned the K16 gene (KRT16A) and two homologous pseudogenes (psiKRT16B and psiKRT16C), allowing development of a genomic mutation detection strategy based on a long-range PCR, which is specific for the functional K16 gene. We report a novel heterozygous 3 bp deletion mutation (388del3) in K16 in a sporadic case of PC-1. The mutation was detected in genomic DNA and confirmed at the mRNA level by RT-PCR, showing that our genomic PCR system is reliable for K16 mutation detection. Using this system, we carried out the first prenatal diagnosis for PC-1 using CVS material, correctly predicting a normal fetus. This work will greatly improve K16 mutation analysis and allow predictive testing for PC-1 and the related phenotype of FNEPPK.
Smith
F J
FJ
Epithelial Genetics Group, Department of Dermatology and Cutaneous Biology, Jefferson Medical College, 233 South 10th Street, Philadelphia, PA 19107, USA.
McKusick
V A
VA
Nielsen
K
K
Pfendner
E
E
Uitto
J
J
McLean
W H
WH
D000015:Abnormalities, Multiple / Q000175:diagnosis / Q000235:genetics*; D000328:Adult; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004476:Ectodermal Dysplasia / Q000175:diagnosis / Q000235:genetics*; D005820:Genetic Testing; D006801:Humans; D007633:Keratins / Q000235:genetics*; D007645:Keratoderma, Palmoplantar / Q000235:genetics; D007972:Leukoplakia, Oral / Q000235:genetics; D008297:Male; D009264:Nails, Malformed / Q000235:genetics; D011296:Prenatal Diagnosis / Q000379:methods*; D012333:RNA, Messenger / Q000235:genetics; D017422:Sequence Analysis, DNA
D012333:RNA, Messenger; D007633:Keratins