Neonatal diabetes in Ukraine: incidence, genetics, clinical phenotype and treatment.

BACKGROUND: Neonatal diabetes has not been previously studied in Ukraine. We investigated the genetic etiology in patients with onset of diabetes during the first 9 months of life. METHODS: We established a Pediatric Diabetes Register to identify patients diagnosed with diabetes before 9 months of age. Genetic testing was undertaken for 42 patients with permanent or transient diabetes diagnosed within the first 6 months of life (n=22) or permanent diabetes diagnosed between 6 and 9 months (n=20). RESULTS: We determined the genetic etiology in 23 of 42 (55%) patients; 86% of the patients diagnosed before 6 months and 20% diagnosed between 6 and 9 months. The incidence of neonatal diabetes in Ukraine was calculated to be 1 in 126,397 live births. CONCLUSIONS: Genetic testing for patients identified through the Ukrainian Pediatric Diabetes Register identified KCNJ11 and ABCC8 mutations as the most common cause (52%) of neonatal diabetes. Transfer to sulfonylureas improved glycemic control in all 11 patients.

Germline mutations in the oncogene EZH2 cause Weaver syndrome and increased human height.

The biological processes controlling human growth are diverse, complex and poorly understood. Genetic factors are important and human height has been shown to be a highly polygenic trait to which common and rare genetic variation contributes. Weaver syndrome is a human overgrowth condition characterised by tall stature, dysmorphic facial features, learning disability and variable additional features. We performed exome sequencing in four individuals with Weaver syndrome, identifying a mutation in the histone methyltransferase, EZH2, in each case. Sequencing of EZH2 in additional individuals with overgrowth identified a further 15 mutations. The EZH2 mutation spectrum in Weaver syndrome shows considerable overlap with the inactivating somatic EZH2 mutations recently reported in myeloid malignancies. Our data establish EZH2 mutations as the cause of Weaver syndrome and provide further links between histone modifications and regulation of human growth.

Stickler syndrome caused by COL2A1 mutations: genotype-phenotype correlation in a series of 100 patients.

Stickler syndrome is an autosomal dominant connective tissue disorder caused by mutations in different collagen genes. The aim of our study was to define more precisely the phenotype and genotype of Stickler syndrome type 1 by investigating a large series of patients with a heterozygous mutation in COL2A1. In 188 probands with the clinical diagnosis of Stickler syndrome, the COL2A1 gene was analyzed by either a mutation scanning technique or bidirectional fluorescent DNA sequencing. The effect of splice site alterations was investigated by analyzing mRNA. Multiplex ligation-dependent amplification analysis was used for the detection of intragenic deletions. We identified 77 different COL2A1 mutations in 100 affected individuals. Analysis of the splice site mutations showed unusual RNA isoforms, most of which contained a premature stop codon. Vitreous anomalies and retinal detachments were found more frequently in patients with a COL2A1 mutation compared with the mutation-negative group (P<0.01). Overall, 20 of 23 sporadic patients with a COL2A1 mutation had either a cleft palate or retinal detachment with vitreous anomalies. The presence of vitreous anomalies, retinal tears or detachments, cleft palate and a positive family history were shown to be good indicators for a COL2A1 defect. In conclusion, we confirm that Stickler syndrome type 1 is predominantly caused by loss-of-function mutations in the COL2A1 gene as >90% of the mutations were predicted to result in nonsense-mediated decay. On the basis of binary regression analysis, we developed a scoring system that may be useful when evaluating patients with Stickler syndrome.

Beta-cell dysfunction in classic transient neonatal diabetes is characterized by impaired insulin response to glucose but normal response to glucagon.

OBJECTIVE: To investigate beta-cell function and the long-term health of four case subjects presenting with chromosome 6-associated transient neonatal diabetes (TND). RESEARCH DESIGN AND METHODS: Two unrelated case subjects presenting with paternal uniparental isodisomy of chromosome 6 (UPD6) and two siblings with a paternally inherited duplication of 6q24 were studied. Three case subjects presented with neonatal diabetes that recurred at 4-17 years, while diabetes was incidentally discovered in the other case subject at 14 years of age. beta-Cell function was investigated after diabetes relapse by means of an oral glucose tolerance test (OGTT), an intravenous glucose tolerance test (IVGTT), and glucagon tests. The quantitative insulin sensitivity check index (QUICKI) was calculated from fasting blood samples as an estimate of insulin sensitivity. RESULTS: beta-Cell function was investigated at diabetes relapse in two case subjects: the insulin response to both an OGTT and IVGTT was low, whereas the basal levels of C-peptide were normal. No evidence of insulin resistance was found. Residual beta-cell function was further explored by a glucagon test in all subjects at the age of 16-28 years and was found to be normal. Final height was within the normal percentiles, whereas one case, who had been poorly controlled since puberty, presented with diabetes-related microvascular complications. CONCLUSIONS: In patients with chromosome 6-associated TND, the beta-cell is preserved and able to secrete insulin through the stimulatory G protein pathway while exhibiting a specific defect of insulin secretion after glucose stimulation. This form of diabetes can be managed with insulin or diet, although new therapeutic agents (glucagon-like synthetic analogs) may prove useful in the future. Lack of treatment leads to long-lasting hyperglycemia without the risk of ketoacidosis but associated with microangiopathy in adult life.