Ulnar-mammary syndrome (UMS) is a rare genetic disorder that causes abnormalities in the hands, lower arms (forearms), and mammary glands. Symptoms are variable but may include underdevelopment of the bones in the forearm (radius and ulna), abnormal nipples, and obesity, as well as abnormalities in the sweat and mammary glands. Affected individuals may also have delayed puberty and abnormal genitalia may be seen in affected males.
UMS is caused by a change (mutation) in the TBX3 gene. The disorder is inherited in an autosomal dominant way, which means a mutation in only one of the two gene copies a person has is enough to cause the condition. Affected children are usually diagnosed at birth when abnormalities are noticed in the forearm bones (seen on x-rays) and with the nipples (seen on physical exam). Genetic testing is used to confirm the diagnosis.
There is no cure for this condition, but surgery may be needed to repair forearm abnormalities. If your child has been diagnosed with UMS, talk with their doctor about all treatment options. Meeting with a genetic counselor may be helpful to determine who else in the family is at risk for this condition. Support groups can help connect you with other families affected by this condition.