Diagnosis and confirmation of epidermolytic palmoplantar keratoderma by the identification of mutations in keratin 9 using denaturing high-performance liquid chromatography.
BACKGROUND
Epidermolytic palmoplantar keratoderma (EPPK) is one of a number of disorders characterized by diffuse thickening of palm and sole skin. Although EPPK is not a life-threatening condition, palmoplantar keratoderma can be associated with cancer and heart disease and therefore differential diagnosis is important so that adequate surveillance can be provided for the more serious conditions. Most cases of EPPK are caused by mutations in the gene encoding the palm- and sole-specific keratin 9 (K9), and this provides an option for molecular diagnosis of this condition.


OBJECTIVE
To identify the molecular basis of diffuse palmoplantar keratoderma in four British families.


METHODS
Denaturing high-performance liquid chromatography (dHPLC) and DNA sequencing were used to screen exon 1 of the k9 gene for sequence variations.


RESULTS
The dHPLC profiles obtained from individuals with EPPK differed from control samples, indicating sequence variations within the fragment analysed. The profiles varied between families, suggesting that underlying mutations were different for each family; this was confirmed by DNA sequencing. In three cases previously reported mutations were found that resulted in the change of methionine156 to valine and arginine162 to either tryptophan or glutamine. A novel mutation was identified in a fourth family that changed valine170 to methionine. dHPLC was used to screen control samples for this sequence variation and confirmed that it was not a common polymorphism.


CONCLUSIONS
These results confirm the diagnosis of EPPK in these families and underline the usefulness of dHPLC as a method of screening samples for heterozygous mutations.
Rugg
E L
EL
Centre for Cutaneous Research, Barts and The London, Queen Mary's School of Medicine and Dentistry, University of London, 2 Newark Street, London E1 2AT, UK. E.L.RUGG@qmul.ac.uk
Common
J E A
JE
Wilgoss
A
A
Stevens
H P
HP
Buchan
J
J
Leigh
I M
IM
Kelsell
D P
DP
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D006801:Humans; D007633:Keratins / Q000235:genetics*; D007645:Keratoderma, Palmoplantar / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D009154:Mutation / Q000235:genetics*; D010375:Pedigree
D007633:Keratins