Edition of 28 February 2023

A new study published in the EJHG (European journal of human genetics) identified mono and bi-allelic (recessive) variants in KRT17, within seven members (of two consanguineous Pakistani families) who express an atypical PC (pachyonychia congenita) characterized by an unusual combination of pachyonychia, plantar keratoderma, folliculitis, alopecia, sparse eyebrows, dental anomalies and variable acanthosis nigricans of neck, dry skin, palmoplantar hyperhidrosis, recurrent blisters on soles and/or arms, rough sparse hair on scalp and keratosis pilaris. Both exome sequencing and linkage mapping demonstrated recessive inheritance whereas Sanger sequencing indicated heterozygosity for the causal variant, reiterating caution for simple targeted sequencing for genetic testing. Testing parents for variants found in sibs could uncover recessive inheritance also in other KRT genes.