Table 1.

Molecular Genetic Testing Used in Pachyonychia Congenita (PC)

Gene 1Proportion of PC
Attributed to
Pathogenic Variants
in Gene 2, 3		Proportion of Pathogenic Variants 4 Detectable by Method
Sequence analysis 5Gene-targeted deletion/duplication analysis 6
KRT6A 304/774 (39%)>99%Unknown 7
KRT6B 70/774 (9%)>99%Unknown 7
KRT6C 22/774 (3%)>99%Unknown 7
KRT16 247/774 (32%)>99%Unknown 7
KRT17 8130/774 (17%)>99%Unknown 7
1.

See Table A. Genes and Databases for chromosome locus and protein.

2.

Pathogenic variants in at least 800 individuals have been reported [International PC Research Registry, Human Intermediate Filament Database].

3.

The numbers in this table refer only to those individuals enrolled in the International PC Research Registry (IPCRR); not all are published but the data are available on the website.

4.

See Molecular Genetics for information on allelic variants detected in this gene.

5.

Sequence analysis detects variants that are benign, likely benign, of uncertain significance, likely pathogenic, or pathogenic. Variants may include small intragenic deletions/insertions and missense, nonsense, and splice site variants; typically, exon or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.

6.

Gene-targeted deletion/duplication analysis detects intragenic deletions or duplications. Methods used may include a range of techniques such as quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and a gene-targeted microarray designed to detect single-exon deletions or duplications.

7.

No data on gene-targeted del/dup analysis are available.

8.

To date all identified pathogenic variants causing steatocystoma multiplex (SM) are in KRT17. Careful reexamination of those with SM caused by a heterozygous KRT17 pathogenic variant have identified subtle nail changes in some family members. Many individuals with a clinical diagnosis of SM and no nails changes also have no identifiable pathogenic variant in KRT17. Therefore, genetic heterogeneity is likely for SM.

From: Pachyonychia Congenita

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