Search

Diabet. Med. 27, 1195–1200 (2010) Aims Permanent neonatal diabetes is a rare condition affecting 1 in 300 000–400 000 live births; only in 60% of cases it is possible to identify the genetic defect. The condition of pancreatic agenesis is rarer still. Only two genes are known to determine this phenotype: PDX-1 and PTF1A. Congenital heart defects are among the most common developmental anomalies, affecting 1% of newborns, and the GATA4 gene is less frequently involved in these disorders. An Italian child with pancreatic agenesis and an atrial septal defect was genetically investigated to elucidate whether the association of the two pathologies was casual, or represented a new pancreatic/cardiac syndrome. Methods A panel of pancreas development genes, including GCK, Kir6.2, PTF1A, PDX-1, HNF-1A, NgN3, SOX17, SOX7, SOX9, INS, HNF1-B and SUR1 plus the GATA4 gene, were screened for characterization of pancreatic agenesis and cardiac defect. Results Screening for genes causing permanent neonatal diabetes was negative. A novel mutation in GATA4 (c1512C>T) was detected and functional characterization confirmed a reduced activity of the protein. In the family members, the GATA4 mutation co-segregates with a cardiac phenotype, but not with pancreatic agenesis. Conclusions We describe the first report of pancretic agenesis with an associated cardiac defect and a mutation in the GATA4 gene. We could not establish that the GATA4 mutation was causative for pancreatic agenesis and further genetic investigation to detect the genetic cause of the pancreas agenesis was unsuccessful. We conclude that, the two pathologies are attributable to two independent events. [ABSTRACT FROM AUTHOR]

Aims Heterozygous activating mutations in KCNJ11, which encodes the Kir6.2 subunit of the pancreatic ATP-sensitive potassium (KATP) channel, cause both permanent and transient neonatal diabetes. Identification of KCNJ11 mutations has important therapeutic implications, as many patients can replace insulin injections with sulphonylurea tablets. The aim was to determine if a KCNJ11 mutation was responsible for a dominantly inherited form of diabetes mellitus, showing variability in age at diagnosis, in an Italian family. Methods We sequenced KCNJ11 in members of a three-generation family with variable phenotypes of dominantly inherited diabetes mellitus. One had transient early-onset diabetes, one had impaired glucose tolerance during the second pregnancy, and two had young-onset diabetes. None of the subjects showed permanent neonatal diabetes or neurological symptoms. Results A novel heterozygous mutation (c. 679C→G and c. 680A→T) was identified, resulting in a GAG→CTG (E227L) substitution in KCNJ11. Functional studies of recombinant heterozygous KATP channels revealed a small reduction in channel inhibition by ATP (IC50 of 15 µmol/l and 38 µmol/l for wild-type and heterozygous channels, respectively) and an increase in the resting KATP current. This would be expected to impair insulin secretion. The results are in agreement with the mild phenotype of the patients. Conclusions Our results broaden the spectrum of diabetes phenotypes resulting from KCNJ11 mutations. They indicate testing for KCNJ11 mutations should be considered not only for neonatal diabetes but also for other forms of dominantly inherited diabetes with later onset, especially where these are associated with a low body mass index and low birth weight. [ABSTRACT FROM AUTHOR]