Background: Treacher Collins syndrome-1 (TCS1; OMIM# 154500) is a rare autosomal dominant disease that is defined by congenital craniofacial dysplasia. Here, we report four sporadic and one familial case of TCS1 in Chinese patients with clinical features presenting as hypoplasia of the zygomatic complex and mandible, downslanting palpebral fissures, coloboma of the lower eyelids, and conductive hearing loss.
Materials and methods: Audiological, radiological, and physical examinations were performed. Targeted next-generation sequencing (NGS) was performed to examine the genetics of this disease in five probands, and Sanger sequencing was used to confirm the identified variants. A literature review discusses the pathogenesis, treatment, and prevention of TCS1.
Results: We identified a novel insertion of c.939_940insA (p.Gly314Argfs*35; NM_001135243.1), a novel deletion of c.1766delC (p.Pro589Leufs*7), two previously reported insertions of c.1999_2000insC (p.Arg667Profs*31) and c.4218_4219insG (p.Ser1407Valfs*23), and one previously reported deletion of c.4369_4373delAAGAA (p.Lys1457Glufs*12) in the TCOF1 gene. All five cases exhibited a degree of interfamilial and intrafamilial phenotypic variability. A review of the literature revealed no clear evidence of a genotype-phenotype correlation in TCS1.
Conclusion: Our results expand the variant spectrum of TCOF1 and highlight that NGS is essential for the diagnosis of TCS and that genetic counseling is beneficial for guiding prevention.
Keywords: TCOF1; Treacher Collins syndrome; conductive hearing loss; craniofacial dysplasia.
© 2020 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.