GnRH deficiency: new insights from genetics

The acquisition of a sexually dimorphic phenotype is a critical event in mammalian development. Hypogonadotropic hypogonadism (HH) results from impaired secretion of GnRH. The patients display with delayed puberty, micropenis and cryptorchidism in the male reflecting gonadotropin insufficiency, and amenorrhea in the female. Kallmann's syndrome (KS) is defined by the association of HH and anosmia or hyposmia (absent smelling sense). Segregation analysis in familial cases has demonstrated diverse inheritance patterns, suggesting the existence of several genes regulating GnRH secretion. The X-linked form of the disease was associated with a genetic defect in the KALI gene located on the Xp22.3 region. KAL1 gene encodes an extracellular matrix glycoprotein anosmin-1, which facilitates neuronal growth and migration. Abnormalities in the migratory processes of the GnRH neurons with the olfactory neurons explain the association of HH with anosmia. Recently, mutations in the FGF recepteur 1 (FGFR1) gene were found in KS with autosomal dominant mode of inheritance. The role of FGFR1 in the function of reproduction requires further investigation. Besides HH with anosmia, there are isolated HH (IHH). No human GnRH mutations have been reported although hypogonadal mice due to a GnRH gene deletion exist. In patients with idiopathic HH and without anosmia an increasing number of GnRH receptor (GnRHR) mutations have been described which represent about 50% of familial cases. The clinical features are highly variable and there is a good relationship between genotype and phenotype. A complete loss of function is associated with the most severe phenotype with resistance to pulsatile GnRH treatment, absence of puberty and cryptorchidism in the male. In contrast, milder loss of function mutations causes incomplete failure of pubertal development. The preponderant role of GnRH in the secretion of LH by the gonadotrophs explains the difference of the phenotype between male and female with partial GnRH resistance. Affected females can have spontaneous telarche and normal breast development while affected males exhibit no pubertal development but normal testis volume, a feature described as "fertile-eunuch". High-dose pulsatile GnRH has been used to induce ovulation. Another gene, called GPR54, responsible for idiopathic HH has been recently described by segregation analysis in two different consanguineous families. The GPR54 gene is an orphan receptor, and its putative ligand is the product of the KISS-1 gene, called metastine. Their roles in the function of reproduction are still unknown.     

Genetic interaction of BBS1 mutations with alleles at other BBS loci can result in non-Mendelian Bardet-Biedl syndrome

Bardet-Biedl syndrome is a genetically and clinically heterogeneous disorder caused by mutations in at least seven loci (BBS1-7), five of which are cloned (BBS1, BBS2, BBS4, BBS6, and BBS7). Genetic and mutational analyses have indicated that, in some families, a combination of three mutant alleles at two loci (triallelic inheritance) is necessary for pathogenesis. To date, four of the five known BBS loci have been implicated in this mode of oligogenic disease transmission. We present a comprehensive analysis of the spectrum, distribution, and involvement in non-Mendelian trait transmission of mutant alleles in BBS1, the most common BBS locus. Analyses of 259 independent families segregating a BBS phenotype indicate that BBS1 participates in complex inheritance and that, in different families, mutations in BBS1 can interact genetically with mutations at each of the other known BBS genes, as well as at unknown loci, to cause the phenotype. Consistent with this model, we identified homozygous M390R alleles, the most frequent BBS1 mutation, in asymptomatic individuals in two families. Moreover, our statistical analyses indicate that the prevalence of the M390R allele in the general population is consistent with an oligogenic rather than a recessive model of disease transmission. The distribution of BBS oligogenic alleles also indicates that all BBS loci might interact genetically with each other, but some genes, especially BBS2 and BBS6, are more likely to participate in triallelic inheritance, suggesting a variable ability of the BBS proteins to interact genetically with each other.     

Comparison of the results of PCR-RFLP and reverse hybridization methods used in molecular diagnosis of FMF

Familial Mediterranean fever (FMF) is characterized by recurrent fever, serositis, and arthritis. Due to the abundance of mutations and clinical heterogeneity of the disease, different screening methods have been developed. In this study, we aimed to compare our findings of mutations determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with reverse hybridization (RH) methods. In 152 of 263 patients (57.79%) different mutations were determined with RH. Allelic frequencies were E148Q 6.84%, M680I(G/C) 3.61%, M694V 20.91%, V726A 7.03%, P369S 1.33%, F479L 0.19%, M680I(G/A) 0.76%, M694I 0.57%, K695R 0.57%, A744S 0.38%, R731H 0.38%, and del1692 0%. Frequent mutations were also confirmed by PCR-RFLP. There were no conflicting results between the two methods. Four of these genotypes were homozygous for a single mutation, 15 were heterozygous for two mutations, 8 were heterozygous for a single mutation, 1 was heterozygous for three mutations, and 1 was homozygous for one mutation and heterozygous for another mutation. It has been reported that analytical sensitivity of RH is 97%. We did not find a discrepancy between the two methods. In 21 patients, we detected additional mutations with RH. This finding was regarded as an advantage of RH, and we concluded that this assay is a useful method for detection of first stage FMF mutation screening.     

Familial Mediterranean fever in Syrian patients: <Emphasis Type="Italic">MEFV</Emphasis> gene mutations and genotype–phenotype correlation

Familial Mediterranean fever is an autosomal recessive disorder characterized by recurrent attacks of abdominal pain, synovitis and pleuritis. MEFV gene mutations are responsible for the disease. The objective of this study was to identify the frequency and distribution of 12 MEFV mutations in 153 Syrian patients and perform a genotype–phenotype correlation in the patients’ cohort. Of the 153 unrelated patients investigated, 97 (63.4%) had at least one mutation. The most frequent mutation was M694V (36.5%), followed by V726A (15.2%), E148Q (14.5%), M680I (G/C) (13.2%), and M694I (10.2%) mutations. Rare mutations (R761H, A744S, M680I (G/A), K695R, P369S, F479L and I692del) were also detected in the patients. M694V was associated with the severe form of the disease. The identification of a significant number of FMF patients with no mutations or only one known mutation identified indicates the presence of new mutations in the MEFV gene which will be investigated in the future.     

New insights into fluoroquinolone resistance in Mycobacterium tuberculosis: functional genetic analysis of gyrA and gyrB mutations

Fluoroquinolone antibiotics are among the most potent second-line drugs used for treatment of multidrug-resistant tuberculosis (MDR TB), and resistance to this class of antibiotics is one criterion for defining extensively drug resistant tuberculosis (XDR TB). Fluoroquinolone resistance in Mycobacterium tuberculosis has been associated with modification of the quinolone resistance determining region (QRDR) of gyrA. Recent studies suggest that amino acid substitutions in gyrB may also play a crucial role in resistance, but functional genetic studies of these mutations in M. tuberculosis are lacking. In this study, we examined twenty six mutations in gyrase genes gyrA (seven) and gyrB (nineteen) to determine the clinical relevance and role of these mutations in fluoroquinolone resistance. Transductants or clinical isolates harboring T80A, T80A+A90G, A90G, G247S and A384V gyrA mutations were susceptible to all fluoroquinolones tested. The A74S mutation conferred low-level resistance to moxifloxacin but susceptibility to ciprofloxacin, levofloxacin and ofloxacin, and the A74S+D94G double mutation conferred cross resistance to all the fluoroquinolones tested. Functional genetic analysis and structural modeling of gyrB suggest that M330I, V340L, R485C, D500A, D533A, A543T, A543V and T546M mutations are not sufficient to confer resistance as determined by agar proportion. Only three mutations, N538D, E540V and R485C+T539N, conferred resistance to all four fluoroquinolones in at least one genetic background. The D500H and D500N mutations conferred resistance only to levofloxacin and ofloxacin while N538K and E540D consistently conferred resistance to moxifloxacin only. Transductants and clinical isolates harboring T539N, T539P or N538T+T546M mutations exhibited low-level resistance to moxifloxacin only but not consistently. These findings indicate that certain mutations in gyrB confer fluoroquinolone resistance, but the level and pattern of resistance varies among the different mutations. The results from this study provide support for the inclusion of the QRDR of gyrB in molecular assays used to detect fluoroquinolone resistance in M. tuberculosis.     

Analysis of most common mutations R778G, R778L, R778W, I1102T and H1069Q in Indian Wilson disease patients: Correlation between genotype/phenotype/copper ATPase activity

The present study was intented to estimate the frequencies of the most common mutations (R778L, R778W, R778G, I1102T and H1069Q) of ATP7B in Indian Wilson disease (WD) population and to explore the correlation between genotype/phenotype and copper ATPase activity. A total of 33 WD patients and their family members from North West states of India were examined. The H1069Q, R778W and R778L mutations were absent in these WD patients. R778W and I1102T mutations were present in 36% of WD patients. Family analysis for these mutations using PCR-RFLP documented 5 carriers and 2 asymptomatic WD patients. The copper ATPase activity in WD patients was significantly reduced (50%) than that of control individuals. No significant difference was observed in copper stimulated ATPase activity between homozygous (R778W/R778W, I1102T/I1102T) and compound heterozygous (R778W/unknown mutation, I1102T/unknown mutation) WD patients. Serum ceruloplasmin, serum copper levels were significantly lower in homozygous WD patients than that of compound heterozygous. However, no significant difference was observed in liver copper contents between heterozygous and homozygous patients. In conclusion, the data suggest that R778W and I1102T are most common mutations and provide the basis of genetic (PCR-RFLP) diagnostic tool for Indian WD patients as well as in siblings/parents where biochemical parameters are ambiguous.     

Mutations in TRIOBP, which encodes a putative cytoskeletal-organizing protein, are associated with nonsyndromic recessive deafness

In seven families, six different mutant alleles of TRIOBP on chromosome 22q13 cosegregate with autosomal recessive nonsyndromic deafness. These alleles include four nonsense (Q297X, R788X, R1068X, and R1117X) and two frameshift (D1069fsX1082 and R1078fsX1083) mutations, all located in exon 6 of TRIOBP. There are several alternative splice isoforms of this gene, the longest of which, TRIOBP-6, comprises 23 exons. The linkage interval for the deafness segregating in these families includes DFNB28. Genetic heterogeneity at this locus is suggested by three additional families that show significant evidence of linkage of deafness to markers on chromosome 22q13 but that apparently have no mutations in the TRIOBP gene.     

Analysis of the H626R,A546T,and T538R mutations in the TGFBI gene in patients with corneal stroma lattice dystrophy from Ukraine

An analysis of the mutations H626R (exon 14) and A546T and T538R (exon 12) of the TGFBI gene using the polymerization chain reaction method with subsequent restriction, performed on 52 individuals from 22 unrelated families, together with a clinical diagnosis of different types of lattice corneal dystrophy is carried out. The H626R mutation was discovered in patients in 12 of the 17 families examined with a clinical diagnosis of lattice dystrophy with late manifestation and in six individuals in whom no clinical manifestations had yet appeared. Interestingly, the T538R and H626R mutations, which are associated with lattice dystrophy with late manifestation of the disease, were discovered in two patients with preliminary clinical diagnosis of lattice dystrophy (type I), a condition which is characterized by early manifestation of the disease. The A546T mutation was not found in any of our patients. Possible features of the mutant protein tgfbi and its involvement in the pathogenesis of the disease are also discussed. The results obtained indicate that the analysis of mutations in the TGFBI gene is of considerable importance for differential diagnosis of corneal dystrophy with predictive and therapeutic use as well as for genetic counseling in high-risk families.     

Semaphorin-1a is required for Aedes aegypti embryonic nerve cord development

Although mosquito genome projects have uncovered orthologues of many known developmental regulatory genes, extremely little is known about mosquito development. In this study, the role of semaphorin-1a (sema1a) was investigated during vector mosquito embryonic ventral nerve cord development. Expression of sema1a and the plexin A (plexA) receptor are detected in the embryonic ventral nerve cords of Aedes aegypti (dengue vector) and Anopheles gambiae (malaria vector), suggesting that Sema1a signaling may regulate mosquito nervous system development. Analysis of sema1a function was investigated through siRNA-mediated knockdown in A. aegypti embryos. Knockdown of sema1a during A. aegypti development results in a number of nerve cord phenotypes, including thinning, breakage, and occasional fusion of the longitudinal connectives, thin or absent commissures, and general distortion of the nerve cord. Although analysis of Drosophila melanogaster sema1a loss-of-function mutants uncovered many similar phenotypes, aspects of the longitudinal phenotypes differed between D. melanogaster and A. aegypti. The results of this investigation suggest that Sema1a is required for development of the insect ventral nerve cord, but that the developmental roles of this guidance molecule have diverged in dipteran insects.     

High frequency of 35delG GJB2 mutation and absence of del(GJB6-D13S1830) in Greek Cypriot patients with nonsyndromic hearing loss

Mutations in the GJB2 (Connexin 26) gene are responsible for more than half of all cases of prelingual, recessive, inherited, nonsyndromic deafness in Europe. This paper presents a mutation analysis of the GJB2 and GJB6 (Connexin 30) genes in 30 Greek Cypriot patients with sensorineural nonsyndromic hearing loss compatible with recessive inheritance. Ten of the patients (33.3%) had the 35delG mutation in the GJB2 gene. Moreover, 9 of these were homozygous for the 35delG mutation, whereas 1 patient was in the compound heterozygous state with the disease causing E47X nonsense mutation. Another patient with severe sensorineural hearing loss was heterozygous for the V153I missense mutation. Finally, no GJB6 mutations or the known del(GJB6-D13S1830) were identified in any of the investigated Greek Cypriot nonsyndromic hearing loss patients. This work confirms that the GJB2 35delG mutation is an important pathogenic mutation for hearing loss in the Greek Cypriot population. This finding will be used toward the effective diagnosis of nonsyndromic hearing loss, improve genetic counseling, and serve as a potential therapeutic platform in the future for the affected patients in Cyprus.     

2013 William Allan Award: My Multifactorial Journey

Gonadotropin-releasing hormone (GnRH) neurons originate outside the CNS in the olfactory placode and migrate into the CNS, where they become integral components of the hypothalamic-pituitary-gonadal (HPG) axis. Disruption of this migration results in Kallmann syndrome (KS), which is characterized by anosmia and pubertal failure due to hypogonadotropic hypogonadism. Using candidate-gene screening, autozygosity mapping, and whole-exome sequencing in a cohort of 30 individuals with KS, we searched for genes newly associated with KS. We identified homozygous loss-of-function mutations in FEZF1 in two independent consanguineous families each with two affected siblings. The FEZF1 product is known to enable axons of olfactory receptor neurons (ORNs) to penetrate the CNS basal lamina in mice. Because a subset of axons in these tracks is the migratory pathway for GnRH neurons, in FEZF1 deficiency, GnRH neurons also fail to enter the brain. These results indicate that FEZF1 is required for establishment of the central component of the HPG axis in humans.     

Uroporphyrinogen III synthase knock-in mice have the human congenital erythropoietic porphyria phenotype, including the characteristic light-induced cutaneous lesions

Congenital erythropoietic porphyria (CEP), an autosomal recessive inborn error, results from the deficient but not absent activity of uroporphyrinogen III synthase (URO-synthase), the fourth enzyme in the heme biosynthetic pathway. The major clinical manifestations include severe anemia, erythrodontia, and disfiguring cutaneous involvement due to the accumulation of phototoxic porphyrin I isomers. Murine models of CEP could facilitate studies of disease pathogenesis and the evaluation of therapeutic endeavors. However, URO-synthase null mice were early embryonic lethals. Therefore, knock-in mice were generated with three missense mutations, C73R, V99A, and V99L, which had in vitro-expressed activities of 0.24%, 5.9%, and 14.8% of expressed wild-type activity, respectively. Homozygous mice for all three mutations were fetal lethals, except for mice homozygous for a spontaneous recombinant allele, V99A(T)/V99A(T), a head-to-tail concatemer of three V99A targeting constructs. Although V99A(T)/V99A(T) and C73R/V99A(T) mice had approximately 2% hepatic URO-synthase activity and normal hepatic microsomal heme and hemoprotein levels, they had 20% and 13% of wild-type activity in erythrocytes, respectively, which indicates that sufficient erythroid URO-synthase was present for fetal development and survival. Both murine genotypes showed marked porphyrin I isomer accumulation in erythrocytes, bone, tissues, and excreta and had fluorescent erythrodontia, hemolytic anemia with reticulocytosis and extramedullary erythropoiesis, and, notably, the characteristic light-induced cutaneous involvement. These mice provide insight into why CEP is an erythroid porphyria, and they should facilitate studies of the disease pathogenesis and therapeutic endeavors for CEP.     

<Emphasis Type="Italic">MEFV</Emphasis> gene mutations spectrum among Lebanese patients referred for Familial Mediterranean Fever work-up: Experience of a major tertiary care center

Familial Mediterranean Fever (FMF) is an autosomal recessive inflammatory disorder predominantly affecting people living in or originating from areas around the Mediterranean Sea, mainly Jews, Armenians, Turks, and Arabs. It is characterized by recurrent attacks of inflammation of serosal membranes and fever resulting in acute abdominal, chest, or joint pain. Over 50 MEditerranean FeVer (MEFV) mutations and polymorphisms have been identified in FMF patients. The objective of this study was to analyze the distribution and frequencies of 12 MEFV mutations in 266 referred Lebanese patients using a reverse-hybridization assay. Of the 266 patients, 129 (48.5%) were positive for at least one mutation and 137 (51.5%) had no mutations detected. Of the 129 patients with mutations, 35 were homozygous, 41 were compound heterozygous and 53 were heterozygous. The five most common mutations M694V, E148Q, V726A, M694I and M680I (G/C) accounted for 26.1, 22.2, 21.3, 9.6 and 7.7%, respectively. The A744S, F479L, R761H and I692del were encountered in 2.9% of patients; P369S and M680I (G/A) were found in 1.2% of patients while K695R was absent. The spectrum of the MEFV mutations among our sampled Lebanese FMF patients shows the high heterogeneity at the allelic level when compared to Arab and non-Arab populations. The most important feature was the relatively high frequency of the E148Q in our study group that allows us to question it as a mutation rather than a polymorphism. Further studies should be conducted to evaluate the role of the E148Q allele.     

High frequency of GJB2 mutation W24X among Slovak Romany (Gypsy) patients with non-syndromic hearing loss (NSHL)

Mutations in the GJB2 gene (connexin 26) represent a major cause of autosomal recessive non-syndromic hearing loss (NSHL) worldwide. In most Caucasian populations, the 35delG mutation in this gene was found to account for up to 50% of cases of the genetic non-syndromic childhood deafness. In populations of non-European ethnic background, other GJB2 gene mutations are occasionally common, e.g. 167delT in Ashkenazi Jews, R143W in Africaans and 235delC in Koreans. In this work, DNA samples from 54 unrelated NSHL patients from endogamous and inbred population of Slovak Roms (Gypsies) from Eastern Slovakia were screened for GJB2 mutations. The coding region of the GJB2 gene of patients was sequenced and mutations W24X, R127H, V153I, L90P and V37I were found. In Slovak Romany population, mutation W24X accounts for 23.2%, R127H for 19.4%, 35delG for 8.3%, V153I for 3.7%, L90P for 3.7% and V37I for 0.9% of screened chromosomes. As the W24X mutation was previously found in India and Pakistan, were from the European Romanies originate, it was brought by the European Romnanies from their Indian homeland. The carrier frequency of 35delG was estimated for Slovak non-Romany population to be 3.3%, and for Slovak Romany population to 0.88%. The carrier frequency of W24X varied in different Slovak Romany subpopulations from 0.0% up to 26.1%.     

A shift in the salt bridge interaction of residues D620 and E621 mediates the constitutive activation of Jak2-H538Q/K539L

Jak2 mutations in the exon 14 and exon 12 regions that cause constitutive activation have been associated with myeloproliferative neoplasms. We have previously shown that a pi stacking interaction between F617 and F595 is important for the constitutive activation of Jak2-V617F (Gnanasambandan et al., Biochemistry 49:9972-9984, 2010). Here, using a combination of molecular dynamics (MD) simulations and in vitro mutagenesis, we studied the molecular mechanism for the constitutive activation of the Jak2 exon 12 mutation, H538Q/K539L. The activation levels of Jak2-H538Q/K539L were found to be similar to that of Jak2-V617F, and Jak2-H538Q/K539L/V617F. Data from MD simulations indicated a shift in the salt bridge interactions of D620 and E621 with K539 in Jak2-WT to R541 in Jak2-H538Q/K539L. When compared to Jak2-WT, K539A mutation resulted in increased activation, while K539D or K539E mutations diminished Jak2 activation by 50 %. In the context of Jak2-H538Q/K539L, R541A mutation reduced its activation by 50 %, while R541D and R541E mutations returned its activation levels to that of Jak2-WT. Collectively, these results indicate that a shift in the salt bridge interaction of D620 and E621 with K539 in Jak2-WT to R541 in Jak2-H538Q/K539L is critical for constitutive activation of this Jak2 exon 12 mutant.     

Characterization of the effect of Melanocortin 1 Receptor,a member of the hair color genetic locus,in alpaca (Lama pacos) fleece color differentiation

Little is known about the inheritance and influence of the fleece color gene Melanocortin 1 Receptor (MC1R). Melanocortin 1 Receptor (MC1R) is a well-known gene responsible for red versus black fleece pigmentation and is hypothesized to be a candidate gene for variation in alpaca coloration patterns. Inheritance of red versus black pigmentation in the context of genetic mutation is well understood in many domesticated mammals. We characterized the MC1R gene in a population of multi-colored alpacas in order to better understand its effect on coat color in the alpaca. Our characterization of the alpaca MC1R gene revealed 11 mutations. Of these one is a 4 bp deletion, four are silent mutations and six are single nucleotide polymorphisms (SNPs) that alter the amino acid sequence (T28V, M87V, S126G, T128I, S196F, R301C). No mutation correlated completely with fleece color in alpacas at the MC1R locus. This may be due to the epistatic relationship of MC1R with other coat color genes especially agouti signaling protein (ASIP).     

Heterozygous fitness effects of clonally transmitted genomes in waterfrogs

The European waterfrog Rana esculenta (RL‐genotype) is a natural hybrid between R. ridibunda (RR) and R. lessonae (LL) and reproduces by hybridogenesis, i.e. it eliminates the L‐genome from the germline and produces gametes only containing the clonally transmitted R‐genome. Because of the lack of recombination, R‐genomes are prone to accumulate spontaneous deleterious mutations. The homozygous effects of such mutations become evident in matings between hybrids: their offspring possess two clonal R‐genomes and are generally inviable. However, the evolutionary fate of R. esculenta mainly depends on the heterozygous effects of mutations on the R‐genome. These effects may be hidden in the hybrid R. esculenta because it has been shown to benefit from spontaneous heterosis. To uncouple clonal inheritance from hybridity, I crossed R. esculenta with R. ridibunda to produce nonhybrid offspring with one clonal and one sexual R‐genome, and compared their survival and larval performance with normal, sexually produced R. ridibunda tadpoles. Because environmental stress can enhance the negative effects of mutation accumulation, I measured the performance at high and low food levels. There was no indication that tadpoles with a clonal genome performed worse at either food level, suggesting that at least in the larval stage, R. esculenta benefits from heterosis without incurring any costs because of heterozygous effects of deleterious mutations on the clonally transmitted R‐genome.     

Compound heterozygous mutations in the SUR1 (ABCC 8) subunit of pancreatic K(ATP) channels cause neonatal diabetes by perturbing the coupling between Kir6.2 and SUR1 subunits

KATP channels regulate insulin secretion by coupling β-cell metabolism to membrane excitability. These channels are comprised of a pore-forming Kir6.2 tetramer which is enveloped by four regulatory SUR1 subunits. ATP acts on Kir6.2 to stabilize the channel closed state while ADP (coordinated with Mg(2+)) activates channels via the SUR1 domains. Aberrations in nucleotide-binding or in coupling binding to gating can lead to hyperinsulinism or diabetes. Here, we report a case of diabetes in a 7-mo old child with compound heterozygous mutations in ABCC8 (SUR1[A30V] and SUR1[G296R]). In unison, these mutations lead to a gain of KATP channel function, which will attenuate the β-cell response to increased metabolism and will thereby decrease insulin secretion. (86)Rb(+) flux assays on COSm6 cells coexpressing the mutant subunits (to recapitulate the compound heterozygous state) show a 2-fold increase in basal rate of (86)Rb(+) efflux relative to WT channels. Experiments on excised inside-out patches also reveal a slight increase in activity, manifested as an enhancement in stimulation by MgADP in channels expressing the compound heterozygous mutations or homozygous G296R mutation. In addition, the IC 50 for ATP inhibition of homomeric A30V channels was increased ~6-fold, and was increased ~3-fold for both heteromeric A30V+WT channels or compound heterozygous (A30V +G296R) channels. Thus, each mutation makes a mechanistically distinct contribution to the channel gain-of-function that results in neonatal diabetes, and which we predict may contribute to diabetes in related carrier individuals.