Variable features of transient neonatal diabetes mellitus with paternal isodisomy of chromosome 6

We describe two patients who suffered transient neonatal diabetes mellitus (TDNM), due to paternal isodisomy of chromosome 6. One patient, now 5 years old, had severe intra-uterine growth retardation, but recovered normal gro wth parameters. The other patient, currently 12 years old, had a normal bir th weight but showed impaired post-natal growth; in addition to TNDM the pa tient presented with cardiac and thyroid abnormalities. These cases may sug gest that the clinical phenotype of TNDM is more variable than previously b elieved. The contribution of genetic and epigenetic factors needs to be det ermined to elucidate the phenotype-genotype relationships of this disease.