Ulnar-Mammary syndrome with TBX3 gene mutation in a Chinese family: A case report and literature review.

Ulnar-Mammary syndrome (UMS) is a rare monogenic disorder caused by mutations of the TBX3 gene. This paper reported a family of UMS. The proband, a 15-year old man, was presented with mammary gland dysplasia, ulnar limb defect, short stature, and delayed growth. Whole exome sequencing revealed a 1294_1301dup mutation in exon 6 of the TBX3 gene. Sanger sequencing was used to verify other members of the family, which suggested his mother also carried the same mutation, but merely resulting in the dysplasia of her left little finger. Notably, unilateral finger involvement without any systemic organ involvement was unusual in UMS patients. The proband then was treated with recombinant human growth hormone (rhGH) and human chorionic gonadotropin (hCG). After a year and a half, his height and secondary sexual characteristics were significantly improved. The clinical manifestations of the disease are highly heterogeneous, which is easy to be misdiagnosed and missed. When the diagnosis is unclear, genetic testing is helpful for auxiliary diagnosis.