Palmoplantar keratoderma and erythrokeratodermas

Gene: AQP5

Green List (high evidence)

Comment when marking as ready: Green review, >3 cases, and MOI confirmed by OMIM.

Created: 13 Mar 2017, 9:07 a.m.

Comment on list classification: Updated rating from Amber to Green: 1 Green expert review plus >3 cases supporting causation.

Created: 13 Mar 2017, 9:06 a.m.

Comment on list classification: Updated rating from Red to Amber ready for Expert review. >3 unrelated cases of AQP5 mutations linked to Palmoplantar keratoderma (PPK) in at least UK, Danish, Swedish and Chinese families.

Created: 10 Jan 2017, 2:54 p.m.

PMID:23867895 (Cao et al., 2014) report a Chinese family with PPKB, including 10 affected individuals. The proband was a 28 year old man. Exome sequencing in 3 indiciduals (2 affected and 1 non-affected) detected variants in AQP5 and SLC4A8. Only the missense AQP5 mutation (c.367A>T, p.Asn123Tyr) segregated with the PPKB phenotype in all 23 family members.

Created: 10 Jan 2017, 2:51 p.m.

>3 AQP5 variants listed in OMIM for 'Palmoplantar keratoderma, Bothnian type' (PPKB, OMIM:600231) from PMID:23830519, Blaydon et al., 2013) and profile Swedish and UK families. The A38E mutation (c.113C-A transversion) represents a founder mutation and is found in individuals of 7 Swedish families affected with PPKB.

Created: 10 Jan 2017, 2:47 p.m.

PMID:27255181 (Kroigard et al., 2016) report a Danish family with diffuse non-epidermolytic palmoplantar keratoderma of Bothnian type caused by a heterozygous c.562C>T / p.Arg188Cys mutation in the AQP5 gene. The Proband was a 36 year old male, and the proband's 8-year old son (who exhibits a similar phenotype) was found to be heterozygous for the same AQP5 mutation.

Created: 10 Jan 2017, 2:46 p.m.