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Genetics
The condition is caused by genetic mutations in one of four genes that encode keratin proteins specific to the epithelial tissues affected in the two forms of the disorder. PC1 is caused by mutations in keratin 6A (protein name K6A; gene name KRT6A) or keratin 16 (protein K16; gene KRT16). The PC2 form is due to mutations in the genes encoding keratin hB (protein name K6B; gene name KRT6B) or keratin 17 (protein K17; gene KRT17). Three of the genes causing PC were identified in 1995[1][2] with the fourth gene following in 1998.[3]
Inheritance of PC
PC follows an autosomal dominant pattern of inheritance, i.e. on average 50% of the offspring of an affected person will inherit the disorder, regardless of gender. The risk is 50% for each pregnancy, regardless of the outcome of previous pregnancies. Often, a solitary case exists in a family and these are due to occurrence of a new mutation (often referred to as a sporadic or spontaneous mutation).
Patient support organization
A patient support group exists for helping individuals affected by PC, called "PC Project". They actively seek PC patients, offer help and support, arrange genetic testing to confirm the diagnosis of PC, organize meetings for patients and researchers, and sponsor research into developing new treatments for the condition. A wealth of information on all aspects of PC can be found on their website ([4]).
References
- ^ McLean WHI et al. (191235) Keratin 16 and keratin 17 mutations cause pachyonychia congenita. Nature Genetics 9:273-278. Abstract available here[1].
- ^ Bowden PE et al. (1985) Mutation of a type II keratin gene (K6a) in pachyonychia congenita. Nature Genetics 10:363-365. Abstract available here[2].
- ^ Smith FJD et al. (1998) A mutation in human keratin K6b produces a phenocopy of the K17 disorder pachyonychia congenita type 2. Human Molecular Genetics 7:1143-1148. Abstract available here[3].
