Cardiac rhabdomyomas in BHD?

BHD is typically characterised by fibrofolliculomas, pulmonary cysts with or without pneumothoraces, and renal tumours. Although other forms of cancer have been reported in BHD patients, direct links with folliculin mutations have not been confirmed.

This week Bondavalli et al., (2015) reported on the formation of two cardiac rhabdomyomas in a 5 month old boy later confirmed to have BHD. Cardiac rhabdomyomas are common associated with Tuberous Sclerosis Complex (TSC)  however no mutations where found in either the TSC1 or TSC2 genes. Extended family BHD diagnoses lead to testing the child, his mother and grandmother; all three were confirmed to carry a folliculin mutation. The authors suggest that aberrant mTOR pathway activity resulting from folliculin loss could be a cause of rhabdomyoma formation in this case as it is in TSC (Kotulska et al., 2009). This is the only reported cardiac rhabdomyoma in a BHD patient so currently it is not possible to determine if there is a causative connection between folliculin mutations and rhabdomyoma formation.

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