Treacher Collins Syndrome 3

A number sign (#) is used with this entry because Treacher Collins syndrome-3 (TCS3) is caused by compound heterozygous mutation in the POLR1C gene (610060) on chromosome 6p21.

Description

Treacher Collins syndrome is a disorder of craniofacial development characterized by a combination of bilateral downward slanting of the palpebral fissures, colobomas of the lower eyelids with a paucity of eyelashes medial to the defect, hypoplasia of the facial bones, cleft palate, malformation of the external ears, atresia of the external auditory canals, and bilateral conductive hearing loss (Dauwerse et al., 2011).

For additional phenotypic information and a discussion of genetic heterogeneity of Treacher Collins syndrome, see TCS1 (154500).

Clinical Features

Richieri-Costa et al. (1993) and Splendore et al. (2000) both reported sibs with Treacher Collins syndrome who were born to normal parents. The possibility of either nonpenetrance or germline mosaicism in one of the parents could not be discarded.

Inheritance

Treacher Collins syndrome-3 is an autosomal recessive disorder (Dauwerse et al., 2011).

Molecular Genetics

Dauwerse et al. (2011) analyzed the POLR1C gene in 252 individuals with Treacher Collins syndrome and identified 3 patients, including 1 from a family previously studied by Splendore et al. (2000), with compound heterozygous mutations (610060.0001-610060.0005, respectively).