Wolfram syndrome, which is sometimes referred to as "DIDMOAD" (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness), is an autosomal recessive neurodegenerative disorder for which only insulin-dependent diabetes mellitus and optic atrophy are necessary to make the diagnosis. Researchers have mapped Wolfram syndrome to chromosome 4p16.1, and, recently, a gene encoding a putative transmembrane protein has been cloned and mutations have been identified in patients. To pursue the possibility of locus heterogeneity, 16 patients from four different families were recruited. These patients, who have the Wolfram syndrome phenotype, also have additional features that have not previously been reported. There is an absence of diabetes insipidus in all affected family members. In addition, several patients have profound upper gastrointestinal ulceration and bleeding. With the use of three microsatellite markers (D4S432, D4S3023, and D4S2366) reported to be linked to the chromosome 4p16.1 locus, we significantly excluded linkage in three of the four families. The two affected individuals in one family showed homozygosity for all three markers from the region of linkage on chromosome 4p16.1. For the other three families, genetic heterogeneity for Wolfram syndrome was verified by demonstration of linkage to chromosome 4q22-24. In conclusion, we report the unique clinical findings and linkage-analysis results of 16 patients with Wolfram syndrome and provide further evidence for the genetic heterogeneity of this disorder. We also provide data on a new locus that plays a role in the etiology of insulin-dependent diabetes mellitus.

Summary Management guidelines continue to identify metformin as initial pharmacologic antidiabetic therapy of choice for people with type 2 diabetes without contraindications, despite recent randomized trials that have demonstrated significant improvements in cardiovascular outcomes with newer classes of antidiabetic therapies. The purpose of this review is to summarize the current state of knowledge of metformin's therapeutic actions on blood glucose and cardiovascular clinical evidence and to consider the mechanisms that underlie them. The effects of metformin on glycaemia occur mainly in the liver, but metformin‐stimulated glucose disposal by the gut has emerged as an increasingly import site of action of metformin. Additionally, metformin induces increased secretion of GLP‐1 from intestinal L‐cells. Clinical cardiovascular protection with metformin is supported by three randomized outcomes trials (in newly diagnosed and late stage insulin‐treated type 2 diabetes patients) and a wealth of observational data. Initial evidence suggests that cotreatment with metformin may enhance the impact of newer incretin‐based therapies on cardiovascular outcomes, an important observation as metformin can be combined with any other antidiabetic agent. Multiple potential mechanisms support the concept of cardiovascular protection with metformin beyond those provided by reduced blood glucose, including weight loss, improvements in haemostatic function, reduced inflammation, and oxidative stress, and inhibition of key steps in the process of atherosclerosis. Accordingly, metformin remains well placed to support improvements in cardiovascular outcomes, from diagnosis and throughout the course of type 2 diabetes, even in this new age of improved outcomes in type 2 diabetes.

Although ourgroup of patients was genetically heterogeneous, the ophthalmic findings are consistent with those reported in other series, except for cataract which was highly prevalent but mild and did not contribute significantly to loss of vision.

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Wolfram syndrome (WS) is a recessively inherited disorder associated with recognised clinical features. Bleeding tendency was noticed in some of our patients, although this has not been reported before. We therefore studied this problem in all our WS patients and tried to postulate a possible pathogenesis. At the same time, a genetic linkage study provided evidence of locus heterogeneity of this syndrome and showed that the majority of our patients belong to the second WS locus identified in that study. Our study group consisted of 13 WS patients, belonging to WSF2 locus (group I). Controls consisted of 4 healthy siblings of WS patients (group II) and 7 diabetics who do not have WS (group III). Relevant clinical data were obtained, and a coagulation screen was carried out for all groups. All individuals in the three study groups have normal platelet count, thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (aPTT), clot retraction, Factor VIII activity (FVIIIc) and von Willebrand factor antigen (vWAg). Eleven of the WS patients have prolonged template bleeding time (BT) compared with both control groups. Patients with WS have a longer BT (mean 9.6 min, 95% CL 8.61-10.53 min) than the siblings group (mean 6.75 min, 95% CL 5.52-7.98 min) and the diabetic group (mean 5.49 min, 95% CL 4.56-6.42 min). The differences between the study group and controls are statistically significant, p = 0.02 and 0.0002, respectively. In the three groups, platelet aggregation studies were normal using adenosine diphosphate (ADP), ristocetin and epinephrine. Aggregation with collagen was either absent or impaired, with failure of secondary wave being noticed in 11 of the WS patients (85%) and normal in the control groups. The pathogenesis of this problem is not known, but could be due to an inhibitory effect of vWAgII, deficiency of thrombospondin or a defect in the platelet membrane GPIa/IIa. Bleeding diathesis is a new additional feature to the clinical spectrum of WS, which is probably a feature of the disorder WFS2 and not WFS1, as bleeding has never been reported in the latter. This provides further evidence for the phenotypic and genotypic heterogeneity of this complex disorder and may provide clues to the search for the second gene responsible for this phenotype.