[A de nono I462S mutation in the KRT6A gene is associated with pachyonychia congenita type I].
OBJECTIVE
To analyze the KRT6A gene mutation and mutating patterns in a sporadic Chinese patient with Pachyonychia congenita (PC)-1 so as to provide a basis for gene diagnosis and genetic counseling of this disorder.


METHODS
Genomic DNA was extracted from whole blood by standard methods from a female patient with PC-1 and her parents, and from 50 normal, unrelated individuals. Primers for specific amplification of the structural KRT6A gene without co amplification of homologous genes were designed and synthesized. All exons of the gene and their flanking intronic sequences were amplified using polymerase chain reaction (PCR) and subjected to automatic DNA sequencing. The mutation was confirmed by Mbo I restriction digestion of the KRT6A-specific PCR products.


RESULTS
Direct sequencing of the PCR products revealed a novel heterozygous missense mutation, I462S in the KRT6A gene, which resulted from T to G transversion at nucleotide 1385 (1385T > G) in exon 7 was detected in the patient. This mutation would result in the substitution of Isoleucine by Serine at codon 462 (I462S) located in the end 2B domain of keratin 6A. No such mutation was found in the patient's parents by sequencing of PCR products and this mutation was confirmed in the patient and excluded from both parents and 50 normal, unrelated controls by restriction analysis of PCR fragments using Mbo I enzyme.


CONCLUSIONS
A de novo missense mutation in the KRT6A gene, I462S, has been found in a sporadic PC-1 patient. The identification of this novel mutation in the KRT6A gene provides further evidence that mutation in the KRT6A gene causes PC-1 phenotype.
Kang
Xiao-jing
XJ
Institute of Dermatology, Chinese Academy of Medical Sciences & Peking Union Medical College, Nanjing 210042, China.
Sun
Miao
M
Yang
Wei
W
Yu
Min
M
Ju
Qiang
Q
Lo
Wilson H Y
WH
Xia
Long-qing
LQ
Zhang
Xue
X
D001483:Base Sequence; D002675:Child, Preschool; D004476:Ectodermal Dysplasia / Q000235:genetics*; D005091:Exons; D005260:Female; D015894:Genome, Human; D006801:Humans; D007633:Keratins / Q000235:genetics*; D053564:Keratins, Hair-Specific; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009264:Nails, Malformed / Q000235:genetics*; D017354:Point Mutation; D012871:Skin Diseases / Q000235:genetics*
C456200:KRT71 protein, human; D053564:Keratins, Hair-Specific; D007633:Keratins