We report the case of a 16 year old female with congenital glomerulocystic kidney disease. Given a strong family history of renal disease, a molecular karyotype was performed. This revealed 17q12 del, with a 1.4 megabase deletion on the long arm of chromosome 17. Microdeletions in this region, encoding the hepatocyte nuclear factor-1 beta (HNF1B), cause renal cysts and diabetes syndrome (RCAD).
Phenotypic features of RCAD that were subsequently identified in our patient were maturity-onset diabetes of the young 5 (MODY5) and the recently identified hypomagnesaemia with elevated urinary magnesium. No genital tract abnormalities were detected on ultrasonography, although this has been widely documented in the literature.
Here we describe a possible new phenotypic feature of RCAD. Our patient exhibits hyperostosis of her skull bones. Furthermore, despite a concurrent eating disorder requiring inpatient management, our patient has surprisingly preserved bone mineral density. To our knowledge, bone hypertrophy as a feature of RCAD is yet to be described in the literature.