Partial paternal uniparental disomy of chromosome 6 in an infant with neonatal diabetes, macroglossia, and craniofacial abnormalities

Neonatal diabetes, which can be transient or permanent, is defined as hyper glycemia that presents within the first month of life and requires insulin therapy. Transient neonatal diabetes mellitus has been associated with abno rmalities of the paternally inherited copy of chromosome 6, including dupli cations of a portion of the long arm of chromosome 6 and uniparental disomy , implicating overexpression of an imprinted gene in this disorder. To date , all patients with transient neonatal diabetes mellitus and uniparental di somy have had complete paternal isodisomy. We describe a patient with neona tal diabetes, macroglossia, and craniofacial abnormalities, with partial pa ternal uniparental disomy of chromosome 6 involving the distal portion of 6 q, from 6q24-qter. This observation demonstrates that mitotic recombination of chromosome 6 can also give rise to uniparental disomy and neonatal diab etes, a situation similar to that observed in Beckwith-Wiedemann syndrome, another imprinted disorder. This finding has clinical implications, since s omatic mosaicism for uniparental disomy of chromosome 6 should also be cons idered in patients with transient neonatal diabetes mellitus.