AdermatoglyphiaQ82.8

Isolated congenital choroidal matoglyphia is a very rare, autosomal dominant inherited, monotopic, non-syndromic disorder of the palms and soles. In this case, the papillary ridges are missing in the affected individuals. Thus, these individuals leave no fingerprints. The malformation is associated with a reduced number of sweat gland orifices and decreased transpiration of the palms and soles.

The disorder is caused by a mutation in the SMARCAD1 gene on chromosome 4 (Nousbeck J et al. 2011). SMARCAD1 encodes a member of the SNF subfamily of helicase proteins (SMARCAD helicase). Evidence indicated a transversion in a splice site in a non-coding 3' lying exon of the SMARCAD1 gene. The point mutation results in a truncation of the gene product. The SMARCAD helicase mutant was also detected in the skin of the subjects.

Newborn

The encoded SMARCAD helicase plays a crucial role in the restoration of heterochromatin organization and the propagation of epigenetic patterns after DNA replication by mediating histone H3/H4 deacetylation.

The mutation found in an affected Swiss family in 2011 is a point mutation in which a purine base is exchanged for a pyrimidine base (a so-called transversion). The point mutation leads to a shortening of the gene product and thus probably to a protein that is restricted in function.

A variant of isolated congenital choroidal matoglyphia is the so-called Basan syndrome in which congenital choroidal matoglyphia is combined with facial milia, reduced sweating, contactures, acral blistering, and nail dystrophies. (Valentine MN et al 2018)