Cousin Syndrome Due to TBX15 Gene Variants: Three Novel Cases and Review of the Literature.

Cousin syndrome (MIM#260660) is a rare genetic disorder characterized by short stature, pelvi-scapular dysplasia and craniofacial dysmorphism, due to biallelic pathogenic variants in the TBX15 gene. So far, only six molecularly confirmed cases have been reported in the literature. Herein, we report three novel individuals from two unrelated families carrying homozygous novel variants in the TBX15 gene causing Cousin syndrome with detailed phenotypic description. We review the literature and discuss differential diagnoses. This report confirms that Cousin syndrome is a clinically recognizable condition, with typical dysmorphic features, short stature, hypoplastic scapula and iliac wings, a high prevalence of hip dislocation and humero-radial synostosis, transmission deafness and strabismus. More case descriptions are needed to precise the prevalence of intellectual disability in this condition, a feature that seems strikingly variable among reports.