The cytochrome b (cyt b) gene structure was characterized for different agronomically important plant pathogens, such as Puccinia recondita f sp tritici (Erikss) CO Johnston, P graminis f sp tritici Erikss and Hennings, P striiformis f sp tritici Erikss, P coronata f sp avenae P Syd & Syd, P hordei GH Otth, P recondita f sp secalis Roberge, P sorghi Schwein, P horiana Henn, Uromyces appendiculatus (Pers) Unger, Phakopsora pachyrhizi Syd & P Syd, Hemileia vastatrix Berk & Broome, Alternaria solani Sorauer, A alternata (Fr) Keissl and Plasmopara viticola (Berk & Curt) Berlese & de Toni. The sequenced fragment included the two hot spot regions in which mutations conferring resistance to QoI fungicides may occur. The cyt b gene structure of these pathogens was compared with that of other species from public databases, including the strobilurin-producing fungus Mycena galopoda (Pers) P Kumm, Saccharomyces cerevisiae Meyer ex Hansen, Venturia inaequalis (Cooke) Winter and Mycosphaerella fijiensis Morelet. In all rust species, as well as in A solani, resistance to QoI fungicides caused by the mutation G143A has never been reported. A type I intron was observed directly after the codon for glycine at position 143 in these species. This intron was absent in pathogens such as A alternata, Blumeria graminis (DC) Speer, Pyricularia grisea Sacc, Mycosphaerella graminicola (Fuckel) J Schröt, M fijiensis, V inaequalis and P viticola, in which resistance to QoI fungicides has occurred and the glycine is replaced by alanine at position 143 in the resistant genotype. The present authors predict that a nucleotide substitution in codon 143 would prevent splicing of the intron, leading to a deficient cytochrome b, which is lethal. As a consequence, the evolution of resistance to QoI fungicides based on G143A is not likely to evolve in pathogens carrying an intron directly after this codon.

Until early 2000, permanent and transient neonatal diabetes mellitus (NDM), defined as diabetes with onset within 6 weeks from birth that requires insulin therapy for at least 2 weeks, were considered exceedingly rare conditions, with a global incidence of 1:500,000–1:400,000 live births. The new definition of NDM recently adopted, that includes patients with diabetes onset within 6 months of age, has prompted studies that have set the incidence of the permanent form alone between 1:210,000 and 1:260,000 live births. Aim of the present work was to ascertain the incidence of NDM (i.e. permanent + transient form) in Italy for years 2005–2010. Patients referred to the Italian reference laboratory for NDM between years 2005 and 2010 and screened for mutations in common NDM genes (KCNJ11, ABCC8, and INS) and for uniparental isodisomy of chromosome 6 (UDP6) were reviewed. A questionnaire aimed at identifying NDM cases investigated in other laboratories was sent to 54 Italian reference centers for pediatric diabetes. Twenty-seven patients with NDM born between 2005 and 2010 were referred to the reference laboratory. In this group, a mutation of either KCNJ11, ABCC8 or INS was found in 18 patients, and a case with UDP6 was identified. Questionnaires revealed 4 additional cases with transient neonatal diabetes due to UDP6. Incidence of NDM was calculated at 1:90,000 (CI: 1:63,000–1:132,000) live births. Thus, with the definition currently in use, about 6 new cases with NDM are expected to be born in Italy each year.

Monogenic diabetes is highly prevalent in patients referred to Italian pediatric diabetes centers. A genetic diagnosis guided the therapeutic decisions, allowed the formulation of a prognosis regarding chronic diabetic complications for a relevant number of patients (i.e.,GCK/MODY), and helped to provide genetic counseling.

Aims/hypothesisThe aim of this study was to investigate the genetic aetiology of permanent diabetes mellitus with onset in the first 12 months of age.MethodsWe studied 46 probands with permanent, insulin-requiring diabetes with onset within the first 6 months of life (permanent neonatal diabetes mellitus [PNDM]/monogenic diabetes of infancy [MDI]) (group 1) and eight participants with diabetes diagnosed between 7 and 12 months of age (group 2). KCNJ11, INS and ABCC8 genes were sequentially sequenced in all patients. For those who were negative in the initial screening, we examined ERN1, CHGA, CHGB and NKX6-1 genes and, in selected probands, CACNA1C, GCK, FOXP3, NEUROG3 and CDK4. The incidence rate for PNDM/MDI was calculated using a database of Italian patients collected from 1995 to 2009.ResultsIn group 1 we found mutations in KCNJ11, INS and ABCC8 genes in 23 (50%), 9 (19.5%) and 4 (8.6%) patients respectively, and a single homozygous mutation in GCK (2.1%). In group 2, we identified one incidence of a KCNJ11 mutation. No genetic defects were detected in other loci. The incidence rate of PNDM/MDI in Italy is estimated to be 1:210,287.Conclusions/interpretationGenetic mutations were identified in ~75% of non-consanguineous probands with PNDM/MDI, using sequential screening of KCNJ11, INS and ABCC8 genes in infants diagnosed within the first 6 months of age. This percentage decreased to 12% in those with diabetes diagnosed between 7 and 12 months. Patients belonging to the latter group may either carry mutations in genes different from those commonly found in PNDM/MDI or have developed an early-onset form of autoimmune diabetes.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-011-2094-8) contains supplementary material, which is available to authorised users.

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Biallelic insulin receptor (INSR) gene mutations cause congenital syndromes of severe insulin resistance (SIR) known as Donohue syndrome (DS) and Rabson-Mendenhall syndrome (RMS). At presentation, DS and RMS are difficult to differentiate since they share many clinical features; however, while patients with DS usually die within 1 year of birth, individuals classified as RMS can reach adult age. INSR mutations can be also found in pubertal females with hyperinsulinism, hyperandrogenism, and acanthosis nigricans (type A SIR). We studied the INSR gene in five subjects with congenital SIR and in a patient with type A SIR. Nine biallelic INSR gene mutations (eight novels, including an in-frame deletion of INSR signal peptide) were identified in patients with congenital SIR; a heterozygous, spontaneous INSR mutation was detected in the patient with type A SIR. Two probands, presenting severe hirsutism at birth, died at the age of 3 months and were classified as DS, while other 2, currently 2 and 3 years old, were diagnosed with RMS (patients 3 and 4). The fifth patient with congenital SIR died when 14 months old. Nephrocalcinosis, hyperaldosteronism, hyperreninemia, and hypokalemia, in the absence of hypertension, were discovered in patients 3 and 5 when 24 and 4 months old, respectively. Patient 3, now 3 years/3 months old, still shows hyperreninemic hyperaldosteronism requiring potassium supplementation. We conclude that renal abnormalities resembling antenatal Bartter's syndrome type II, recently reported also by others, is a common observation in patients with congenital SIR.

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Gain-of-function mutations of KCNJ11 can cause permanent neonatal diabetes mellitus, but only rarely after 6 months of age. Specific uncommon mutations KCNJ11 give rise to a syndrome defined as developmental delay, epilepsy, and neonatal diabetes (DEND), or – more frequently – to a milder sub-type lacking epilepsy, denoted as intermediate-DEND (iDEND). Our aim was to consider a possible monogenic etiology in a 12-yr-old boy with early onset diabetes and mild neurological features. We studied a subject diagnosed with diabetes at 21 months of age, and negative to type 1 diabetes autoantibodies testing. He had learning difficulties during primary school, and a single episode of seizures at the age of 10 yr. We performed direct DNA sequencing of the KCNJ11 gene with subsequent functional study of mutated channels in COSm6 cells. The patient's clinical response to oral glyburide (Glyb) was assessed. Motor coordination was evaluated before and after 6 and 12 months of Glyb therapy. Sequencing of the KCNJ11 gene detected the novel, spontaneous mutation S225T, combined with deletion of amino acids 226–232. In vitro studies revealed that the mutation results in a KATP channel with reduced sensitivity to the inhibitory action of ATP. Glyb improved diabetes control (hemoglobin A1c on insulin: 52 mmol/mol/6.9%; on Glyb: 36 mmol/mol/5.4%) and also performance on motor coordination tests that were impaired before the switch of therapy. We conclude that KCNJ11/S225T, del226-232 mutation caused a mild iDEND form in our patient. KCNJ11 should be considered as the etiology of diabetes even beyond the neonatal period if present in combination with negative autoantibody testing and even mild neurological symptoms.