Neonatal diabetes mellitus, congenital hypothyroidism, hepatic fibrosis, polycystic kidneys, and congenital glaucoma: a new autosomal recessive syndrome?

Consanguineous Marriage and Its Association With Genetic Disorders in Saudi Arabia: A Review

Consanguineous marriages, where spouses are related by blood, have been a longstanding practice in human history. The primary medical concern with consanguineous marriages is the increased risk of genetic disorders. When closely related individuals reproduce, there is a higher probability that both parents carry the same genetic mutation. In Arab countries, especially Saudi Arabia, the rate of consanguineous marriage is high compared with Western European and Asian countries. This high rate is directly proportionate with elevated risk of genetic disorders, including congenital heart diseases, renal diseases, and rare blood disorders. Additionally, it was noted that the rate of negative postnatal outcomes is higher in consanguineous marriages compared with the general population. These observations indicate the necessity of tackling this area and highlighting the consequences of this practice. In this review, we aim to discuss the current evidence regarding the association between consanguineous marriages and genetic disorders in Saudi Arabia.

GLIS3 expression in the thyroid gland in relation to TSH signaling and regulation of gene expression

Loss of GLI-Similar 3 (GLIS3) function in mice and humans causes congenital hypothyroidism (CH). In this study, we demonstrate that GLIS3 protein is first detectable at E15.5 of murine thyroid development, a time at which GLIS3 target genes, such as Slc5a5 (Nis), become expressed. This, together with observations showing that ubiquitous Glis3KO mice do not display major changes in prenatal thyroid gland morphology, indicated that CH in Glis3KO mice is due to dyshormonogenesis rather than thyroid dysgenesis. Analysis of GLIS3 in postnatal thyroid suggested a link between GLIS3 protein expression and blood TSH levels. This was supported by data showing that treatment with TSH, cAMP, or adenylyl cyclase activators or expression of constitutively active PKA enhanced GLIS3 protein stability and transcriptional activity, indicating that GLIS3 activity is regulated at least in part by TSH/TSHR-mediated activation of PKA. The TSH-dependent increase in GLIS3 transcriptional activity would be critical for the induction of GLIS3 target gene expression, including several thyroid hormone (TH) biosynthetic genes, in thyroid follicular cells of mice fed a low iodine diet (LID) when blood TSH levels are highly elevated. Like TH biosynthetic genes, the expression of cell cycle genes is suppressed in ubiquitous Glis3KO mice fed a LID; however, in thyroid-specific Glis3 knockout mice, the expression of cell cycle genes was not repressed, in contrast to TH biosynthetic genes. This indicated that the inhibition of cell cycle genes in ubiquitous Glis3KO mice is dependent on changes in gene expression in GLIS3 target tissues other than the thyroid.

The role of primary cilia in thyroid diseases

Primary cilia (PC) are non-motile and microtube-based organelles protruding from the surface of almost all thyroid follicle cells. They maintain homeostasis in thyrocytes and loss of PC can result in diverse thyroid diseases. The dysfunction of structure and function of PC are found in many patients with common thyroid diseases. The alterations are associated with the cause, development, and recovery of the diseases and are regulated by PC-mediated signals. Restoring normal PC structure and function in thyrocytes is a promising therapeutic strategy to treat thyroid diseases. This review explores the function of PC in normal thyroid glands. It summarizes the pathology caused by PC alterations in thyroid cancer (TC), autoimmune thyroid diseases (AITD), hypothyroidism, and thyroid nodules (TN) to provide comprehensive references for further study.

Genetic perspectives on childhood monogenic diabetes: Diagnosis, management, and future directions

Monogenic diabetes is caused by one or even more genetic variations, which may be uncommon yet have a significant influence and cause diabetes at an early age. Monogenic diabetes affects 1 to 5% of children, and early detection and gene-tically focused treatment of neonatal diabetes and maturity-onset diabetes of the young can significantly improve long-term health and well-being. The etiology of monogenic diabetes in childhood is primarily attributed to genetic variations affecting the regulatory genes responsible for beta-cell activity. In rare instances, mutations leading to severe insulin resistance can also result in the development of diabetes. Individuals diagnosed with specific types of monogenic diabetes, which are commonly found, can transition from insulin therapy to sulfonylureas, provided they maintain consistent regulation of their blood glucose levels. Scientists have successfully devised materials and methodologies to distinguish individuals with type 1 or 2 diabetes from those more prone to monogenic diabetes. Genetic screening with appropriate findings and interpretations is essential to establish a prognosis and to guide the choice of therapies and management of these interrelated ailments. This review aims to design a comprehensive literature summarizing genetic insights into monogenetic diabetes in children and adolescents as well as summarizing their diagnosis and mana-gement.

Direct and INdirect effects analysis of Genetic lOci (DINGO): A software package to increase the power of locus discovery in GWAS meta-analyses of perinatal phenotypes and traits influenced by indirect genetic effects

Perinatal traits are influenced by genetic variants from both fetal and maternal genomes. Genome-wide association studies (GWAS) of these phenotypes have typically involved separate fetal and maternal scans, however, this approach may be inefficient as it does not utilize the information shared across the individual GWAS. In this manuscript we investigate the performance of three strategies to detect loci in maternal and fetal GWAS of the same trait: (i) the traditional strategy of analysing maternal and fetal GWAS separately; (ii) a novel two degree of freedom test which combines information from maternal and fetal GWAS; and (iii) a novel one degree of freedom test where signals from maternal and fetal GWAS are meta-analysed together conditional on the estimated sample overlap. We demonstrate through a combination of analytical formulae and data simulation that the optimal strategy depends on the extent of sample overlap/relatedness between the maternal and fetal GWAS, the correlation between own and offspring phenotypes, whether loci jointly exhibit fetal and maternal effects, and if so, whether these effects are directionally concordant. We apply our methods to summary results statistics from a recent GWAS meta-analysis of birth weight from deCODE, the UK Biobank and the Early Growth Genetics (EGG) consortium. Both the two degree of freedom (213 loci) and meta-analytic approach (226 loci) dramatically increase the number of robustly associated genetic loci for birth weight relative to separately analysing the scans (183 loci). Our best strategy identifies an additional 62 novel loci compared to the most recent published meta-analysis of birth weight and implicates both known and new biological pathways in the aetiology of the trait. We implement our methods in the online DINGO (Direct and INdirect effects analysis of Genetic lOci) software package, which allows users to perform one and/or two degree of freedom tests easily and computationally efficiently across the genome. We conclude that whilst the novel two degree of freedom test may be particularly useful for the analysis of certain perinatal phenotypes where many loci exhibit discordant maternal and fetal genetic effects, for most phenotypes, a simple meta-analytic strategy is likely to perform best, particularly in situations where maternal and fetal GWAS only partially overlap.

Role of GLIS3 in thyroid development and in the regulation of gene expression in thyroid specific Glis3KO mice

Loss of GLI-Similar 3 (GLIS3) function in mice and humans causes congenital hypothyroidism (CH). In this study, we demonstrate that GLIS3 protein is first detectable at E15.5 of murine thyroid development, a time when GLIS3 target genes, such as Slc5a5 (Nis), become also expressed. We further show that Glis3KO mice do not display any major changes in prenatal thyroid gland morphology indicating that CH in Glis3KO mice is due to dyshormonogenesis rather than thyroid dysgenesis. Analysis of thyroid-specific Glis3 knockout (Glis3-Pax8Cre) mice fed either a normal or low-iodine diet (ND or LID) revealed that, in contrast to ubiquitous Glis3KO mice, thyroid follicular cell proliferation and the expression of cell cycle genes were not repressed suggesting that the inhibition of thyroid follicular cell proliferation in ubiquitous Glis3KO mice is related to loss of GLIS3 function in other cell types. However, the expression of several thyroid hormone biosynthesis-, extracellular matrix (ECM)-, and inflammation-related genes was still suppressed in Glis3-Pax8Cre mice particularly under conditions of high blood levels of thyroid stimulating hormone (TSH). We further demonstrate that treatment with TSH, protein kinase A (PKA) or adenylyl cyclase activators or expression of constitutively active PKA enhances GLIS3 protein and activity, suggesting that GLIS3 transcriptional activity is regulated in part by TSH/TSHR-mediated activation of the PKA pathway. This mechanism of regulation provides an explanation for the dramatic increase in GLIS3 protein expression and the subsequent induction of GLIS3 target genes, including several thyroid hormone biosynthetic genes, in thyroid follicular cells of mice fed a LID.

GLIS3: A Critical Transcription Factor in Islet β-Cell Generation

Understanding of pancreatic islet biology has greatly increased over the past few decades based in part on an increased understanding of the transcription factors that guide this process. One such transcription factor that has been increasingly tied to both β-cell development and the development of diabetes in humans is GLIS3. Genetic deletion of GLIS3 in mice and humans induces neonatal diabetes, while single nucleotide polymorphisms (SNPs) in GLIS3 have been associated with both Type 1 and Type 2 diabetes. As a significant progress has been made in understanding some of GLIS3’s roles in pancreas development and diabetes, we sought to compare current knowledge on GLIS3 within the pancreas to that of other islet enriched transcription factors. While GLIS3 appears to regulate similar genes and pathways to other transcription factors, its unique roles in β-cell development and maturation make it a key target for future studies and therapy.

Genetic syndromes with diabetes: A systematic review

Previous reviews and clinical guidelines have identified 10-20 genetic syndromes associated with diabetes, but no systematic review has been conducted to date. We provide the first comprehensive catalog for syndromes with diabetes mellitus. We conducted a systematic review of MEDLINE, Embase, CENTRAL, PubMed, OMIM, and Orphanet databases for case reports, case series, and observational studies published between 1946 and January 15, 2020, that described diabetes mellitus in adults and children with monogenic or chromosomal syndromes. Our literature search identified 7,122 studies, of which 160 fulfilled inclusion criteria. Our analysis of these studies found 69 distinct diabetes syndromes. Thirty (43.5%) syndromes included diabetes mellitus as a cardinal clinical feature, and 56 (81.2%) were fully genetically elucidated. Sixty-three syndromes (91.3%) were described more than once in independent case reports, of which 59 (93.7%) demonstrated clinical heterogeneity. Syndromes associated with diabetes mellitus are more numerous and diverse than previously anticipated. While knowledge of the syndromes is limited by their low prevalence, future reviews will be needed as more cases are identified. The genetic etiologies of these syndromes are well elucidated and provide potential avenues for future gene identification efforts, aid in diagnosis and management, gene therapy research, and developing personalized medicine treatments.

Case Report: Neonatal Diabetes Mellitus Caused by a Novel GLIS3 Mutation in Twins

Background

Mutations in GLIS3 cause a rare syndrome characterized by neonatal diabetes mellitus (NDM), congenital hypothyroidism, congenital glaucoma and cystic kidneys. To date, 14 mutations in GLIS3 have been reported, inherited in an autosomal recessive manner. GLIS3 is a key transcription factor involved in β-cell development, insulin expression, and development of the thyroid, eyes, liver and kidneys.

Cases

We describe non-identical twins born to consanguineous parents presenting with NDM, congenital hypothyroidism, congenital glaucoma, hepatic cholestasis, cystic kidney and delayed psychomotor development. Sequence analysis of GLIS3 identified a novel homozygous nonsense mutation, c.2392C>T, p.Gln798Ter (p.Q798*), which results in an early stop codon. The diabetes was treated with a continuous subcutaneous insulin infusion pump and continuous glucose monitoring. Fluctuating blood glucose and intermittent hypoglycemia were observed on follow-up.

Conclusions

This report highlights the importance of early molecular diagnosis for appropriate management of NDM. We describe a novel nonsense mutation of GLIS3 causing NDM, extend the phenotype, and discuss the challenges in clinical management. Our findings provide new areas for further investigation into the roles of GLIS3 in the pathophysiology of diabetes mellitus.

Molecular and clinical genetics of the transcription factor GLIS3 in Chinese congenital hypothyroidism

The transcription factor GLIS3 is an important factor in hormone biosynthesis and thyroid development, and mutations in GLIS3 are relatively rare. Deletions of more than one of the 11 exons of GLIS3 occur in most patients with various extrathyroidal abnormalities and congenital hypothyroidism (CH), and only 18 missense variants of GLIS3 related to thyroid disease have been reported. The aim of this study was to report the family history and molecular basis of patients with CH who carry GLIS3 variants. Three hundred and fifty-three non-consanguineous infants with CH were recruited and subjected to targeted exome sequencing of CH-related genes. The transcriptional activity and cellular localization of the variants in GLIS3 were investigated in vitro. We identified 20 heterozygous GLIS3 exonic missense variants, including eight novel sites, in 19 patients with CH. One patient carried compound heterozygous GLIS3 variants (p.His34Arg and p.Pro835Leu). None of the variants affected the nuclear localization. However, three variants (p.His34Arg, p.Pro835Leu, and p.Ser893Phe) located in the N-terminal and C-terminal regions of the GLIS3 protein downregulated the transcriptional activation of several genes required for thyroid hormone (TH) biosynthesis. This study of patients with CH extends the current knowledge surrounding the spectrum of GLIS3 variants and the mechanisms by which they cause TH biosynthesis defects.

Molecular mechanisms of β-cell dysfunction and death in monogenic forms of diabetes

Monogenetic forms of diabetes represent 1%-5% of all diabetes cases and are caused by mutations in a single gene. These mutations, that affect genes involved in pancreatic β-cell development, function and survival, or insulin regulation, may be dominant or recessive, inherited or de novo. Most patients with monogenic diabetes are very commonly misdiagnosed as having type 1 or type 2 diabetes. The severity of their symptoms depends on the nature of the mutation, the function of the affected gene and, in some cases, the influence of additional genetic or environmental factors that modulate severity and penetrance. In some patients, diabetes is accompanied by other syndromic features such as deafness, blindness, microcephaly, liver and intestinal defects, among others. The age of diabetes onset may also vary from neonatal until early adulthood manifestations. Since the different mutations result in diverse clinical presentations, patients usually need different treatments that range from just diet and exercise, to the requirement of exogenous insulin or other hypoglycemic drugs, e.g., sulfonylureas or glucagon-like peptide 1 analogs to control their glycemia. As a consequence, awareness and correct diagnosis are crucial for the proper management and treatment of monogenic diabetes patients. In this chapter, we describe mutations causing different monogenic forms of diabetes associated with inadequate pancreas development or impaired β-cell function and survival, and discuss the molecular mechanisms involved in β-cell demise.

The RNA-binding profile of the splicing factor SRSF6 in immortalized human pancreatic β-cells

In pancreatic β-cells, the expression of the splicing factor SRSF6 is regulated by GLIS3, a transcription factor encoded by a diabetes susceptibility gene. SRSF6 down-regulation promotes β-cell demise through splicing dysregulation of central genes for β-cells function and survival, but how RNAs are targeted by SRSF6 remains poorly understood. Here, we define the SRSF6 binding landscape in the human pancreatic β-cell line EndoC-βH1 by integrating individual-nucleotide resolution UV cross-linking and immunoprecipitation (iCLIP) under basal conditions with RNA sequencing after SRSF6 knockdown. We detect thousands of SRSF6 bindings sites in coding sequences. Motif analyses suggest that SRSF6 specifically recognizes a purine-rich consensus motif consisting of GAA triplets and that the number of contiguous GAA triplets correlates with increasing binding site strength. The SRSF6 positioning determines the splicing fate. In line with its role in β-cell function, we identify SRSF6 binding sites on regulated exons in several diabetes susceptibility genes. In a proof-of-principle, the splicing of the susceptibility gene LMO7 is modulated by antisense oligonucleotides. Our present study unveils the splicing regulatory landscape of SRSF6 in immortalized human pancreatic β-cells.

Case Report: Extended Clinical Spectrum of the Neonatal Diabetes With Congenital Hypothyroidism Syndrome

BACKGROUND

Neonatal diabetes with congenital hypothyroidism (NDH) syndrome is a rare condition caused by homozygous or compound heterozygous mutations in the GLI-similar 3 coding gene GLIS3. Almost 20 patients have been reported to date, with significant phenotypic variability.

CASE PRESENTATION

We describe a boy with a homozygous deletion (exons 5-9) in the GLIS3 gene, who presents novel clinical aspects not reported previously. In addition to neonatal diabetes, congenital hypothyroidism and other known multi-organ manifestations such as cholestasis and renal cysts, he suffered from hyporegenerative anemia during the first four months of life and presents megalocornea in the absence of elevated intraocular pressure. Compensation of partial exocrine pancreatic insufficiency and deficiencies in antioxidative vitamins seemed to have exerted marked beneficial impact on several disease symptoms including cholestasis and TSH resistance, although a causal relation is difficult to prove. Considering reports on persistent fetal hemoglobin detected in a few children with GLIS3 mutations, the transient anemia seen in our patient may represent a further symptom associated with either the GLIS3 defect itself or, secondarily, micronutrient deficiency related to exocrine pancreatic deficiency or cholestasis.

CONCLUSIONS

Our report expands the phenotypic spectrum of patients with GLIS3 mutations and adds important information on the clinical course, highlighting the possible beneficial effects of pancreatic enzyme and antioxidative vitamin substitutions on characteristic NDH syndrome manifestations such as TSH resistance and cholestasis. We recommend to carefully screen infants with GLIS3 mutations for subtle biochemical signs of partial exocrine pancreatic deficiency or to discuss exploratory administration of pancreatic enzymes and antioxidative vitamins, even in case of good weight gain and fecal elastase concentrations in the low-to-normal range.

Transcription factor GLIS3: Critical roles in thyroid hormone biosynthesis, hypothyroidism, pancreatic beta cells and diabetes

GLI-Similar 3 (GLIS3) is a member of the GLIS subfamily of Krüppel-like zinc finger transcription factors that functions as an activator or repressor of gene expression. Study of GLIS3-deficiency in mice and humans revealed that GLIS3 plays a critical role in the regulation of several biological processes and is implicated in the development of various diseases, including hypothyroidism and diabetes. This was supported by genome-wide association studies that identified significant associations of common variants in GLIS3 with increased risk of these pathologies. To obtain insights into the causal mechanisms underlying these diseases, it is imperative to understand the mechanisms by which this protein regulates the development of these pathologies. Recent studies of genes regulated by GLIS3 led to the identification of a number of target genes and have provided important molecular insights by which GLIS3 controls cellular processes. These studies revealed that GLIS3 is essential for thyroid hormone biosynthesis and identified a critical function for GLIS3 in the generation of pancreatic β cells and insulin gene transcription. These observations raised the possibility that the GLIS3 signaling pathway might provide a potential therapeutic target in the management of diabetes, hypothyroidism, and other diseases. To develop such strategies, it will be critical to understand the upstream signaling pathways that regulate the activity, expression and function of GLIS3. Here, we review the recent progress on the molecular mechanisms by which GLIS3 controls key functions in thyroid follicular and pancreatic β cells and how this causally relates to the development of hypothyroidism and diabetes.

Gene of the month: GLIS1-3

The GLIS 1-3 genes belong to a family of transcription factors, the Krüppel-like zinc finger proteins. The GLIS proteins function primarily as activators of transcription (GLIS 1 and 3), while GLIS 2 functions as a repressor. Collectively, the GLIS proteins are involved in a variety of diseases in several organs ranging from Alzheimer's disease, facial dysmorphism, neonatal diabetes mellitus, breast and colon cancers and leukaemia. In particular, loss-of-function mutations in GLIS2 are responsible for an autosomal recessive cystic kidney disease called nephronophthisis, which is characterised by tubular atrophy, interstitial fibrosis and corticomedullary cysts.Of diagnostic value in current practice are the presence of GLIS 3 and 1 fusions with PAX8 in almost 100% of hyalinising trabecular tumours of the thyroid gland. This enables its separation from papillary thyroid cancer.

GLIS1-3 transcription factors: critical roles in the regulation of multiple physiological processes and diseases

Krüppel-like zinc finger proteins form one of the largest families of transcription factors. They function as key regulators of embryonic development and a wide range of other physiological processes, and are implicated in a variety of pathologies. GLI-similar 1-3 (GLIS1-3) constitute a subfamily of Krüppel-like zinc finger proteins that act either as activators or repressors of gene transcription. GLIS3 plays a critical role in the regulation of multiple biological processes and is a key regulator of pancreatic β cell generation and maturation, insulin gene expression, thyroid hormone biosynthesis, spermatogenesis, and the maintenance of normal kidney functions. Loss of GLIS3 function in humans and mice leads to the development of several pathologies, including neonatal diabetes and congenital hypothyroidism, polycystic kidney disease, and infertility. Single nucleotide polymorphisms in GLIS3 genes have been associated with increased risk of several diseases, including type 1 and type 2 diabetes, glaucoma, and neurological disorders. GLIS2 plays a critical role in the kidney and GLIS2 dysfunction leads to nephronophthisis, an end-stage, cystic renal disease. In addition, GLIS1-3 have regulatory functions in several stem/progenitor cell populations. GLIS1 and GLIS3 greatly enhance reprogramming efficiency of somatic cells into induced embryonic stem cells, while GLIS2 inhibits reprogramming. Recent studies have obtained substantial mechanistic insights into several physiological processes regulated by GLIS2 and GLIS3, while a little is still known about the physiological functions of GLIS1. The localization of some GLIS proteins to the primary cilium suggests that their activity may be regulated by a downstream primary cilium-associated signaling pathway. Insights into the upstream GLIS signaling pathway may provide opportunities for the development of new therapeutic strategies for diabetes, hypothyroidism, and other diseases.

Association of Established Thyroid-stimulating Hormone and Free Thyroxine Genetic Variants with Hashimoto's Thyroiditis

Hashimoto's thyroiditis (HT), the most frequent autoimmune thyroid disease (AITD), is characterized by chronic inflammation of the thyroid gland that usually results in hypothyroidism. Thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels are used as clinical determinants of thyroid function. The main aim of this study was to explore the association of established TSH and FT4 genetic variants with HT. We performed a case-control analysis using 23 genetic markers in 200 HT patients and 304 controls. Additionally, we tested the association of selected variants with several thyroid-related quantitative traits in HT cases only. Two genetic variants showed nominal association with HT: rs11935941 near NR3C2 gene (p = 0.0034, OR = 0.57, 95% CI = 0.39-0.83) and rs1537424 near MBIP gene (p = 0.0169, OR = 0.72, 95% CI = 0.55-0.94). Additionally, three SNPs showed nominal association with thyroglobulin antibody (TgAb) levels: rs4804416 in INSR gene (p = 0.0073, β = -0.51), rs6435953 near IGFBP5 gene (p = 0.0081, β = 0.75), and rs1537424 near MBIP gene (p = 0.0117, β = 0.49). GLIS3 genetic variant rs10974423 showed nominal association with thyroid peroxidase antibody (TPOAb) levels (p = 0.0465, β = -0.56) and NRG1 genetic variant rs7825175 was nominally associated with thyroid gland volume (p = 0.0272, β = -0.18). All detected loci were previously related to thyroid function or pathology. Findings from our study suggest biological relevance of NR3C2 and MBIP with HT, although these loci require additional confirmation in a larger replication study.

Alterations in biomechanical properties of the cornea among patients with polycystic kidney disease

PURPOSE

The aim of this study was to evaluate the corneal biomechanical features in polycystic kidney disease (PKD) patients and compare them with the healthy individuals.

METHODS

Totally 81 patients with a mean age of 48.46 ± 14.51 years and 60 control cases with a mean age of 44.68 ± 12.69 years were included in the study. All of the subjects underwent a complete ophthalmological examination, including visual acuity testing, biomicroscopic anterior and posterior segment examinations. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) were evaluated with the ocular response analyzer, and the central corneal thickness was evaluated with Sirius^® corneal topography.

RESULTS

PKD patients had significantly increased CH values, without any alterations in IOP or CCT values, compared with the control cases (p:0.001). Among PKD patients, 23 were having liver cysts accompanying renal cysts. There was not any statistically significant difference between PKD patients with or without liver cysts regarding biomechanical properties of the cornea. However, both patient groups had statistically significantly increased CH values compared with the control cases.

CONCLUSION

Patients with PKD present with higher CH values than age-matched controls. Larger studies are warranted to elucidate the alterations in corneal biomechanical properties and their clinical relevance in PKD patients.

Congenital urogenital abnormalities in children with congenital hypothyroidism

Background: Congenital hypothyroidism (CH), as one of the most common congenital endocrine disorders, may be significantly associated with congenital malformations. This study investigates urogenital abnormalities in children with primary CH (PCH).

Methods: This case-control study was conducted on 200 children aged three months to 1 year, referred to Amir-Kabir Hospital, Arak, Iran. One hundred children with PCH, as the case group, and 100 healthy children, as the control group, were selected using convenient sampling. For all children, demographic data checklists were filled, and physical examination, abdomen and pelvic ultrasound and other diagnostic measures (if necessary) were performed to evaluate the congenital urogenital abnormalities including anomalies of the penis and urethra, and disorders and anomalies of the scrotal contents.

Results: Among 92 (100%) urogenital anomalies diagnosed, highest frequencies with 37 (40.2%), 26(28.2%) and 9 (9.7%) cases including hypospadias, Cryptorchidism, and hydrocele, respectively. The frequency of urogenital abnormalities among 32 children with PCH, with 52 cases (56.5%) was significantly higher than the frequency of abnormalities among the 21 children in the control group, with 40 cases (43.4%). (OR=2.04; 95%CI: 1.1-3.6; p=0.014).

Conclusion: Our study demonstrated that PCH is significantly associated with the congenital urogenital abnormalities. However, due to the lack of evidence in this area, further studies are recommended to determine the necessity of conducting screening programs for abnormalities of the urogenital system in children with CH at birth.

Extended clinical features associated with novel Glis3 mutation: a case report

BACKGROUND

Mutations in the GLI-similar 3 (GLIS3) gene encoding the transcription factor GLIS3 are a rare cause of neonatal diabetes and congenital hypothyroidism with 12 reported patients to date. Additional features, previously described, include congenital glaucoma, hepatic fibrosis, polycystic kidneys, developmental delay, facial dysmorphism, osteopenia, sensorineural deafness, choanal atresia, craniosynostosis and pancreatic exocrine insufficiency.

CASE PRESENTATION

We report a new case for consanguineous parents with homozygous novel mutation in GLIS3 gene who presented with neonatal diabetes mellitus, severe resistant congenital hypothyroidism, cholestatic liver disease, bilateral congenital glaucoma and facial dysmorphism. There were associated abnormalities in the external genitalia in form of bifid scrotum, bilateral undescended testicles, microphallus and scrotal hypospadias which might be a coincidental finding.

CONCLUSIONS

We suggest that infants with neonatal diabetes associated with dysmorphism should be screened for GLIS3 gene mutations.

The role of GLIS3 in thyroid disease as part of a multisystem disorder

Congenital hypothyroidism is the most common hereditary endocrine disorder. In a small number of cases, mutations have been identified that are associated with maldevelopment and maldescent of the thyroid. Some of these mutations present as syndromes with a multisystem phenotype such as NKX2-1, PAX8, and FOXE. The association of permanent neonatal diabetes and congenital hypothyroidism was first reported in 2003 and subsequently led to the identification GLIS3 as the mutation responsible for this presentation. GLIS3 is a member of the GLI-similar zinc finger protein family encoding for a nuclear protein with five zinc finger domains and maps to chromosome 9p24. Given the role of GLIS3 in transcriptional activation and repression during embryogenesis, in humans, GLIS3 mutations present with multisystem involvement that also includes renal cystic dysplasia, progressive liver fibrosis and osteopenia. Thyroid findings in GLIS3 patients include thyroid aplasia, diminished colloid with interstitial fibrosis at post-mortem, and apparently normal gross thyroid anatomy on ultrasonography but with temporary TSH resistance on treatment. To date no biological mechanism has explained this variable presentation.

Emerging roles of GLIS3 in neonatal diabetes, type 1 and type 2 diabetes

GLI-similar 3 (GLIS3), a member of the Krüppel-like zinc finger protein subfamily, is predominantly expressed in the pancreas, thyroid and kidney. Glis3 mRNA can be initially detected in mouse pancreas at embryonic day 11.5 and is largely restricted to β cells, pancreatic polypeptide-expressing cells, as well as ductal cells at later stage of pancreas development. Mutations in GLIS3 cause a neonatal diabetes syndrome, characterized by neonatal diabetes, congenital hypothyroidism and polycystic kidney. Importantly, genome-wide association studies showed that variations of GLIS3 are strongly associated with both type 1 diabetes (T1D) and type 2 diabetes (T2D) in multiple populations. GLIS3 cooperates with pancreatic and duodenal homeobox 1 (PDX1), v-maf musculoaponeurotic fibrosarcoma oncogene family, protein A (MAFA), as well as neurogenic differentiation 1 (NEUROD1) and potently controls insulin gene transcription. GLIS3 also plays a role in β cell survival and likely in insulin secretion. Any perturbation of these functions may underlie all three forms of diabetes. GLIS3, synergistically with hepatocyte nuclear factor 6 (HNF6) and forkhead box A2 (FOXA2), controls fetal islet differentiation via transactivating neurogenin 3 (NGN3) and impairment of this function leads to neonatal diabetes. In addition, GLIS3 is also required for the compensatory β cell proliferation and mass expansion in response to insulin resistance, which if disrupted may predispose to T2D. The increasing understanding of the mechanisms of GLIS3 in β cell development, survival and function maintenance will provide new insights into disease pathogenesis and potential therapeutic target identification to combat diabetes.

Congenital anomalies of kidney and upper urinary tract in children with congenital hypothyroidism; a case-control study

INTRODUCTION

Congenital hypothyroidism (CH) may be significantly associated with congenital malformations. However, there is little evidence on the relationship between renal and urinary tract anomalies and CH.

OBJECTIVES

The aim of this study was to compare the renal and upper urinary tract anomalies in children with and without primary CH (PCH).

PATIENTS AND METHODS

This case-control study was conducted on 200 children aged 3 months to 1 year, referring to Amir-Kabir hospital, Arak, Iran. One hundred children with PCH, as the case group, and 100 children without CH, as the control group, were selected. For all children, ultrasonography and other diagnostic measures (if necessary) were performed to evaluate renal and upper urinary tract anomalies (ureter and bladder).

RESULTS

The frequency of renal and upper urinary tract anomalies among 43 children with primary CH, with 83 cases (72.8%), was significantly higher than the frequency of anomalies among the 19 children in the control group, with 31 cases (27.1%) (OR = 3; CI 95%: 1.6-5.4; P = 0.001). Among the anomalies studied, only the differences in frequency of uretero-pelvic junction obstruction (UPJO) (OR = 6; CI 95%: 1.3-28; P = 0.018) and hydronephrosis (OR = 22; CI 95%: 5-95; P = 0.001) was significant between the two groups.

CONCLUSION

Our study demonstrated that PCH is significantly associated with the frequency of congenital anomalies of the kidneys and upper urinary tracts. However, further studies are recommended to determine the necessity of conducting screening programs for anomalies of the kidneys and urinary tract in children with CH at birth.

Expanding the Clinical Spectrum Associated With GLIS3 Mutations

CONTEXT

GLIS3 (GLI-similar 3) is a member of the GLI-similar zinc finger protein family encoding for a nuclear protein with 5 C2H2-type zinc finger domains. The protein is expressed early in embryogenesis and plays a critical role as both a repressor and activator of transcription. Human GLIS3 mutations are extremely rare.

OBJECTIVE

The purpose of this article was determine the phenotypic presentation of 12 patients with a variety of GLIS3 mutations.

METHODS

GLIS3 gene mutations were sought by PCR amplification and sequence analysis of exons 1 to 11. Clinical information was provided by the referring clinicians and subsequently using a questionnaire circulated to gain further information.

RESULTS

We report the first case of a patient with a compound heterozygous mutation in GLIS3 who did not present with congenital hypothyroidism. All patients presented with neonatal diabetes with a range of insulin sensitivities. Thyroid disease varied among patients. Hepatic and renal disease was common with liver dysfunction ranging from hepatitis to cirrhosis; cystic dysplasia was the most common renal manifestation. We describe new presenting features in patients with GLIS3 mutations, including craniosynostosis, hiatus hernia, atrial septal defect, splenic cyst, and choanal atresia and confirm further cases with sensorineural deafness and exocrine pancreatic insufficiency.

CONCLUSION

We report new findings within the GLIS3 phenotype, further extending the spectrum of abnormalities associated with GLIS3 mutations and providing novel insights into the role of GLIS3 in human physiological development. All but 2 of the patients within our cohort are still alive, and we describe the first patient to live to adulthood with a GLIS3 mutation, suggesting that even patients with a severe GLIS3 phenotype may have a longer life expectancy than originally described.

HECT E3 Ubiquitin Ligase Itch Functions as a Novel Negative Regulator of Gli-Similar 3 (Glis3) Transcriptional Activity

The transcription factor Gli-similar 3 (Glis3) plays a critical role in the generation of pancreatic ß cells and the regulation insulin gene transcription and has been implicated in the development of several pathologies, including type 1 and 2 diabetes and polycystic kidney disease. However, little is known about the proteins and posttranslational modifications that regulate or mediate Glis3 transcriptional activity. In this study, we identify by mass-spectrometry and yeast 2-hybrid analyses several proteins that interact with the N-terminal region of Glis3. These include the WW-domain-containing HECT E3 ubiquitin ligases, Itch, Smurf2, and Nedd4. The interaction between Glis3 and the HECT E3 ubiquitin ligases was verified by co-immunoprecipitation assays and mutation analysis. All three proteins interact through their WW-domains with a PPxY motif located in the Glis3 N-terminus. However, only Itch significantly contributed to Glis3 polyubiquitination and reduced Glis3 stability by enhancing its proteasomal degradation. Itch-mediated degradation of Glis3 required the PPxY motif-dependent interaction between Glis3 and the WW-domains of Itch as well as the presence of the Glis3 zinc finger domains. Transcription analyses demonstrated that Itch dramatically inhibited Glis3-mediated transactivation and endogenous Ins2 expression by increasing Glis3 protein turnover. Taken together, our study identifies Itch as a critical negative regulator of Glis3-mediated transcriptional activity. This regulation provides a novel mechanism to modulate Glis3-driven gene expression and suggests that it may play a role in a number of physiological processes controlled by Glis3, such as insulin transcription, as well as in Glis3-associated diseases.

Next generation sequencing in endocrine practice

With the completion of the Human Genome Project and advances in genomic sequencing technologies, the use of clinical molecular diagnostics has grown tremendously over the last decade. Next-generation sequencing (NGS) has overcome many of the practical roadblocks that had slowed the adoption of molecular testing for routine clinical diagnosis. In endocrinology, targeted NGS now complements biochemical testing and imaging studies. The goal of this review is to provide clinicians with a guide to the application of NGS to genetic testing for endocrine conditions, by compiling a list of established gene mutations detectable by NGS, and highlighting key phenotypic features of these disorders. As we outline in this review, the clinical utility of NGS-based molecular testing for endocrine disorders is very high. Identifying an exact genetic etiology improves understanding of the disease, provides clear explanation to families about the cause, and guides decisions about screening, prevention and/or treatment. To illustrate this approach, a case of hypophosphatasia with a pathogenic mutation in the ALPL gene detected by NGS is presented.

Bicaudal C1 promotes pancreatic NEUROG3+ endocrine progenitor differentiation and ductal morphogenesis

In human, mutations in bicaudal C1 (BICC1), an RNA binding protein, have been identified in patients with kidney dysplasia. Deletion of Bicc1 in mouse leads to left-right asymmetry randomization and renal cysts. Here, we show that BICC1 is also expressed in both the pancreatic progenitor cells that line the ducts during development, and in the ducts after birth, but not in differentiated endocrine or acinar cells. Genetic inactivation of Bicc1 leads to ductal cell over-proliferation and cyst formation. Transcriptome comparison between WT and Bicc1 KO pancreata, before the phenotype onset, reveals that PKD2 functions downstream of BICC1 in preventing cyst formation in the pancreas. Moreover, the analysis highlights immune cell infiltration and stromal reaction developing early in the pancreas of Bicc1 knockout mice. In addition to these functions in duct morphogenesis, BICC1 regulates NEUROG3(+) endocrine progenitor production. Its deletion leads to a late but sustained endocrine progenitor decrease, resulting in a 50% reduction of endocrine cells. We show that BICC1 functions downstream of ONECUT1 in the pathway controlling both NEUROG3(+) endocrine cell production and ductal morphogenesis, and suggest a new candidate gene for syndromes associating kidney dysplasia with pancreatic disorders, including diabetes.

Four pediatric patients with autosomal recessive polycystic kidney disease developed new-onset diabetes after renal transplantation

NODAT is increasingly prevalent. Compared with adult recipients, NODAT is less prevalent in pediatric renal transplant recipients; however, some risk factors for its development in young patients have been defined. We report four pediatric renal transplant recipients with ARPKD who developed NODAT. We review the current pediatric NODAT literature and hypothesize that ARPKD may be an additional risk factor for NODAT.

Consanguinity in Saudi Arabia: a unique opportunity for pediatric kidney research

Identification of disease-related genes is a critical step in understanding the molecular basis of disease and developing targeted therapies. The genetic study of diseases occurring in the offspring of consanguineous unions is a powerful way to discover new disease genes. Pediatric nephrology provides an excellent example because ∼70% of cases of kidney disease in childhood are congenital with a likely genetic basis. This percentage is likely to be even higher in countries with a high consanguinity rate, such as the Kingdom of Saudi Arabia. However, there are a number of challenges, such as cultural, legal, and religious restrictions, that should be appreciated before carrying out genetic research in a tradition-bound country. In this article, we discuss the background, opportunities, and challenges involved with this unique opportunity to conduct studies of such genetic disorders. Keys to success include collaboration and an understanding of local traditions and laws.

Frequency and spectrum of Wolcott-Rallison syndrome in Saudi Arabia: a systematic review

BACKGROUND

Wolcott-Rallison syndrome (WRS) is caused by recessive EIF2AK3 gene mutations and characterized by permanent neonatal diabetes (PNDM), skeletal dysplasia, and recurrent hepatitis. The frequency of this rare syndrome is largely unknown.

OBJECTIVES

To define the frequency and spectrum of WRS in the Kingdom of Saudi Arabia (KSA) based on published data.

METHODS

The Medline database was searched for published articles on WRS. The number of reported cases from KSA was compared to the total number of WRS cases reported worldwide. The genotype and phenotype of WRS patients from KSA were reviewed.

RESULTS

Ten articles describing 23 WRS patients from 12 Saudi families from 1995 to 2012 were identified. This figure accounts for 27.7% (23/83) of the patients and 22.2% (12/54) of the families with WRS reported worldwide until January 2013. All Saudi patients with WRS presented with PNDM, and they represent 59% of all PNDM cases from WRS. At reporting, 73% of patients experienced recurrent hepatitis, 56.5% had skeletal abnormalities, and 39.1% of them were dead. There was a variation in the phenotype even between affected siblings. Genetic diagnosis was confirmed in all 12 families with no correlation between the genotype and phenotype. Eight of the nine EIF2AK3 mutations were only reported in these families, and one was shared with a patient from Qatar, a neighboring Arab state.

CONCLUSIONS

No study on the frequency of WRS has been published. However, the available data indicate that KSA has the largest collection of patients with WRS worldwide, and nine of the identifiable EIF2AK3 mutations appear to be confined to Arabs. Establishing a national or international registry for WRS would provide more reliable data on this rare condition.

Detection of copy number variants reveals association of cilia genes with neural tube defects

Background

Neural tube defects (NTDs) are one of the most common birth defects caused by a combination of genetic and environmental factors. Currently, little is known about the genetic basis of NTDs although up to 70% of human NTDs were reported to be attributed to genetic factors. Here we performed genome-wide copy number variants (CNVs) detection in a cohort of Chinese NTD patients in order to exam the potential role of CNVs in the pathogenesis of NTDs.

Methods

The genomic DNA from eighty-five NTD cases and seventy-five matched normal controls were subjected for whole genome CNVs analysis. Non-DGV (the Database of Genomic Variants) CNVs from each group were further analyzed for their associations with NTDs. Gene content in non-DGV CNVs as well as participating pathways were examined.

Results

Fifty-five and twenty-six non-DGV CNVs were detected in cases and controls respectively. Among them, forty and nineteen CNVs involve genes (genic CNV). Significantly more non-DGV CNVs and non-DGV genic CNVs were detected in NTD patients than in control (41.2% vs. 25.3%, p<0.05 and 37.6% vs. 20%, p<0.05). Non-DGV genic CNVs are associated with a 2.65-fold increased risk for NTDs (95% CI: 1.24–5.87). Interestingly, there are 41 cilia genes involved in non-DGV CNVs from NTD patients which is significantly enriched in cases compared with that in controls (24.7% vs. 9.3%, p<0.05), corresponding with a 3.19-fold increased risk for NTDs (95% CI: 1.27–8.01). Pathway analyses further suggested that two ciliogenesis pathways, tight junction and protein kinase A signaling, are top canonical pathways implicated in NTD-specific CNVs, and these two novel pathways interact with known NTD pathways.

Conclusions

Evidence from the genome-wide CNV study suggests that genic CNVs, particularly ciliogenic CNVs are associated with NTDs and two ciliogenesis pathways, tight junction and protein kinase A signaling, are potential pathways involved in NTD pathogenesis.

Gli-similar proteins: their mechanisms of action, physiological functions, and roles in disease

Gli-similar (Glis) 1-3 proteins constitute a subfamily of Krüppel-like zinc-finger proteins that are closely related to members of the Gli family. Glis proteins have been implicated in several pathologies, including cystic kidney disease, diabetes, hypothyroidism, fibrosis, osteoporosis, psoriasis, and cancer. In humans, a mutation in the Glis2 gene has been linked to the development of nephronophthisis (NPHP), a recessive cystic kidney disease, while mutations in Glis3 lead to an extended multisystem phenotype that includes the development of neonatal diabetes, polycystic kidneys, congenital hypothyroidism, and facial dysmorphism. Glis3 has also been identified as a risk locus for type-1 and type-2 diabetes and additional studies have revealed a role for Glis3 in pancreatic endocrine development, β-cell maintenance, and insulin regulation. Similar to Gli1-3, Glis2 and 3 have been reported to localize to the primary cilium. These studies appear to suggest that Glis proteins are part of a primary cilium-associated signaling pathway(s). It has been hypothesized that Glis proteins are activated through posttranslational modifications and subsequently translocate to the nucleus where they regulate transcription by interacting with Glis-binding sites in the promoter regions of target genes. This chapter summarizes the current state of knowledge regarding mechanisms of action of the Glis family of proteins, their physiological functions, as well as their roles in disease.

The Krüppel-like zinc finger protein GLIS3 transactivates neurogenin 3 for proper fetal pancreatic islet differentiation in mice

AIMS/HYPOTHESIS

Mutations in GLIS3, which encodes a Krüppel-like zinc finger transcription factor, were found to underlie sporadic neonatal diabetes. Inactivation of Glis3 by gene targeting in mice was previously shown to lead to neonatal diabetes, but the underlying mechanism remains largely unknown. We aimed to elucidate the mechanism of action of GLIS family zinc finger 3 (GLIS3) in Glis3 ( -/- ) mice and to further decipher its action in in-vitro systems.

METHODS

We created Glis3 ( -/- ) mice and monitored the morphological and biochemical phenotype of their pancreatic islets at different stages of embryonic development. We combined these observations with experiments on Glis3 expressed in cultured cells, as well as in in vitro systems in the presence of other reconstituted components.

RESULTS

In vivo and in vitro analyses placed Glis3 upstream of Neurog3, the endocrine pancreas lineage-defining transcription factor. We found that GLIS3 binds to specific GLIS3-response elements in the Neurog3 promoter, activating Neurog3 gene transcription both directly, and synergistically with hepatic nuclear factor 6 and forkhead box A2.

CONCLUSIONS/INTERPRETATION

These results indicate that GLIS3 controls fetal islet differentiation via direct transactivation of Neurog3, a perturbation that causes neonatal diabetes in mice.

Gli-similar (Glis) Krüppel-like zinc finger proteins: insights into their physiological functions and critical roles in neonatal diabetes and cystic renal disease

GLI-similar (Glis) 1-3 proteins constitute a subfamily of the Krüppel-like zinc finger transcription factors that are closely related to the Gli family. Glis1-3 play critical roles in the regulation of a number of physiological processes and have been implicated in several pathologies. Mutations in GLIS2 have been linked to nephronophthisis, an autosomal recessive cystic kidney disease. Loss of Glis2 function leads to renal atrophy and fibrosis that involves epithelial-mesenchymal transition (EMT) of renal tubule epithelial cells. Mutations in human GLIS3 have been implicated in a syndrome characterized by neonatal diabetes and congenital hypothyroidism (NDH) and in some patients accompanied by polycystic kidney disease, glaucoma, and liver fibrosis. In addition, the GLIS3 gene has been identified as a susceptibility locus for the risk of type 1 and 2 diabetes. Glis3 plays a key role in pancreatic development, particularly in the generation of ß-cells and in the regulation of insulin gene expression. Glis2 and Glis3 proteins have been demonstrated to localize to the primary cilium, a signaling organelle that has been implicated in several pathologies, including cystic renal diseases. This association suggests that Glis2/3 are part of primary cilium-associated signaling pathways that control the activity of Glis proteins. Upon activation in the primary cilium, Glis proteins may translocate to the nucleus where they subsequently regulate gene transcription by interacting with Glis-binding sites in the promoter regulatory region of target genes. In this review, we discuss the current knowledge of the Glis signaling pathways, their physiological functions, and their involvement in several human pathologies.

Differential epigenomic and transcriptomic responses in subcutaneous adipose tissue between low and high responders to caloric restriction

BACKGROUND

Caloric restriction is recommended for the treatment of obesity, but it is generally characterized by large interindividual variability in responses. The factors affecting the magnitude of weight loss remain poorly understood. Epigenetic factors (ie, heritable but reversible changes to genomic function that regulate gene expression independently of DNA sequence) may explain some of the interindividual variability seen in weight-loss responses.

OBJECTIVE

The objective was to determine whether epigenetics and gene expression changes may play a role in weight-loss responsiveness.

DESIGN

Overweight/obese postmenopausal women were recruited for a standard 6-mo caloric restriction intervention. Abdominal subcutaneous adipose tissue biopsy samples were collected before (n = 14) and after (n = 14) intervention, and the epigenomic and transcriptomic profiles of the high and low responders to dieting, on the basis of changes in percentage body fat, were compared by using microarray analysis.

RESULTS

Significant DNA methylation differences at 35 loci were found between the high and low responders before dieting, with 3 regions showing differential methylation after intervention. Some of these regions contained genes known to be involved in weight control and insulin secretion, whereas others were localized in known imprinted genomic regions. Differences in gene expression profiles were observed only after dieting, with 644 genes being differentially expressed between the 2 groups. These included genes likely to be involved in metabolic pathways related to angiogenesis and cerebellar long-term depression.

CONCLUSIONS

These data show that both DNA methylation and gene expression are responsive to caloric restriction and provide new insights about the molecular pathways involved in body weight loss as well as methylation regulation during adulthood.

Transcription factor Glis3, a novel critical player in the regulation of pancreatic beta-cell development and insulin gene expression

In this study, we report that the Krüppel-like zinc finger transcription factor Gli-similar 3 (Glis3) is induced during the secondary transition of pancreatic development, a stage of cell lineage specification and extensive patterning, and that Glis3(zf/zf) mutant mice develop neonatal diabetes, evidenced by hyperglycemia and hypoinsulinemia. The Glis3(zf/zf) mutant mouse pancreas shows a dramatic loss of beta and delta cells, contrasting a smaller relative loss of alpha, PP, and epsilon cells. In addition, Glis3(zf/zf) mutant mice develop ductal cysts, while no significant changes were observed in acini. Gene expression profiling and immunofluorescent staining demonstrated that the expression of pancreatic hormones and several transcription factors important in endocrine cell development, including Ngn3, MafA, and Pdx1, were significantly decreased in the developing pancreata of Glis3(zf/zf) mutant mice. The population of pancreatic progenitors appears not to be greatly affected in Glis3(zf/zf) mutant mice; however, the number of neurogenin 3 (Ngn3)-positive endocrine cell progenitors is significantly reduced. Our study indicates that Glis3 plays a key role in cell lineage specification, particularly in the development of mature pancreatic beta cells. In addition, we provide evidence that Glis3 regulates insulin gene expression through two Glis-binding sites in its proximal promoter, indicating that Glis3 also regulates beta-cell function.

Polycystic kidney disease in the medaka (Oryzias latipes) pc mutant caused by a mutation in the Gli-Similar3 (glis3) gene

Polycystic kidney disease (PKD) is a common hereditary disease in humans. Recent studies have shown an increasing number of ciliary genes that are involved in the pathogenesis of PKD. In this study, the Gli-similar3 (glis3) gene was identified as the causal gene of the medaka pc mutant, a model of PKD. In the pc mutant, a transposon was found to be inserted into the fourth intron of the pc/glis3 gene, causing aberrant splicing of the pc/glis3 mRNA and thus a putatively truncated protein with a defective zinc finger domain. pc/glis3 mRNA is expressed in the epithelial cells of the renal tubules and ducts of the pronephros and mesonephros, and also in the pancreas. Antisense oligonucleotide-mediated knockdown of pc/glis3 resulted in cyst formation in the pronephric tubules of medaka fry. Although three other glis family members, glis1a, glis1b and glis2, were found in the medaka genome, none were expressed in the embryonic or larval kidney. In the pc mutant, the urine flow rate in the pronephros was significantly reduced, which was considered to be a direct cause of renal cyst formation. The cilia on the surface of the renal tubular epithelium were significantly shorter in the pc mutant than in wild-type, suggesting that shortened cilia resulted in a decrease in driving force and, in turn, a reduction in urine flow rate. Most importantly, EGFP-tagged pc/glis3 protein localized in primary cilia as well as in the nucleus when expressed in mouse renal epithelial cells, indicating a strong connection between pc/glis3 and ciliary function. Unlike human patients with GLIS3 mutations, the medaka pc mutant shows none of the symptoms of a pancreatic phenotype, such as impaired insulin expression and/or diabetes, suggesting that the pc mutant may be suitable for use as a kidney-specific model for human GLIS3 patients.

A murine model of neonatal diabetes mellitus in Glis3-deficient mice

Glis3 is a member of the Gli-similar subfamily. GLIS3 mutations in humans lead to neonatal diabetes, hypothyroidism, and cystic kidney disease. We generated Glis3-deficient mice by gene-targeting. The Glis3(-/-) mice had significant increases in the basal blood sugar level during the first few days after birth. The high levels of blood sugar are attributed to a decrease in the Insulin mRNA level in the pancreas that is caused by impaired islet development and the subsequent impairment of Insulin-producing cell formation. The pancreatic phenotypes indicate that the Glis3-deficient mice are a model for GLIS3 mutation and diabetes mellitus in humans.

Glis3 is associated with primary cilia and Wwtr1/TAZ and implicated in polycystic kidney disease

In this study, we describe the generation and partial characterization of Krüppel-like zinc finger protein Glis3 mutant (Glis3(zf/zf)) mice. These mice display abnormalities very similar to those of patients with neonatal diabetes and hypothyroidism syndrome, including the development of diabetes and polycystic kidney disease. We demonstrate that Glis3 localizes to the primary cilium, suggesting that Glis3 is part of a cilium-associated signaling pathway. Although Glis3(zf/zf) mice form normal primary cilia, renal cysts contain relatively fewer cells with a primary cilium. We further show that Glis3 interacts with the transcriptional modulator Wwtr1/TAZ, which itself has been implicated in glomerulocystic kidney disease. Wwtr1 recognizes a P/LPXY motif in the C terminus of Glis3 and enhances Glis3-mediated transcriptional activation, indicating that Wwtr1 functions as a coactivator of Glis3. Mutations in the P/LPXY motif abrogate the interaction with Wwtr1 and the transcriptional activity of Glis3, indicating that this motif is part of the transcription activation domain of Glis3. Our study demonstrates that dysfunction of Glis3 leads to the development of cystic renal disease, suggesting that Glis3 plays a critical role in maintaining normal renal functions. We propose that localization to the primary cilium and interaction with Wwtr1 are key elements of the Glis3 signaling pathway.

Increased prevalence of renal and urinary tract anomalies in children with congenital hypothyroidism

OBJECTIVE

We investigated the prevalence of congenital renal and urologic anomalies in children with congenital hypothyroidism to determine whether further renal and urologic investigations would be of benefit.

STUDY DESIGN

Prevalence of congenital hypothyroidism was obtained from the New York State Congenital Malformation Registry. The occurrence of urinary tract anomalies were calculated for children with congenital hypothyroidism and compared to children without congenital hypothyroidism. In addition we obtained congenital hypothyroidism data from New York State newborn screening, and the cases were matched to Congenital Malformation Registry.

RESULTS

Analysis of Congenital Malformation Registry data showed 980 children with congenital hypothyroidism and 3 661 585 children without congenital hypothyroidism born in New York State (1992-2005). Children with congenital hypothyroidism have a significantly increased risk of congenital renal and urological anomalies with the odds ratio (OR) of 13.2 (10.6-16.5). The other significantly increased defects in congenital hypothyroidism were cardiac, gastrointestinal, and skeletal. Analysis of matched data confirmed an increase of congenital renal and urologic anomalies with OR of 4.8 (3.7-6.3).

CONCLUSIONS

Children with congenital hypothyroidism have an increased prevalence of congenital renal and urologic anomalies. We suggest that these children should be evaluated for the presence of congenital renal and urologic anomalies with renal ultrasonography, and that further studies of common genes involved in thyroid and kidney development are warranted.

Neonatal diabetes mellitus because of pancreatic agenesis with dysmorphic features and recurrent bacterial infections

Pancreatic agenesis is a rare cause of neonatal diabetes mellitus (NDM). It can be associated with malformations of the heart, the biliary tract, and the cerebellum. We report an infant with NDM because of pancreatic agenesis, intra-uterine growth retardation, dysmorphic features, and recurrent bacterial infections. He was born to healthy consanguineous parents. With adequate replacement of insulin and pancreatic enzymes, his blood glucose levels were controlled and his weight slowly increased. However, he continued to develop recurrent serious bacterial infections and died at the age of 11 months with sepsis and respiratory failure. Analysis of the PTF1A and PDX1 genes, which have been associated with congenital agenesis of the pancreas, did not reveal any mutation. Genetic abnormalities of chromosome 6 associated with transient neonatal diabetes as well as mutations in the KCNJ11 and ABCC8 genes encoding the pancreatic potassium channel were also excluded as a cause of the NDM in this patient. The association of permanent neonatal diabetes because of pancreatic agenesis, dysmorphism, and non-specific immunodeficiency is previously undescribed and may represent a new possibly autosomal recessive syndrome.

Neonatal diabetes mellitus

An explosion of work over the last decade has produced insight into the multiple hereditary causes of a nonimmunological form of diabetes diagnosed most frequently within the first 6 months of life. These studies are providing increased understanding of genes involved in the entire chain of steps that control glucose homeostasis. Neonatal diabetes is now understood to arise from mutations in genes that play critical roles in the development of the pancreas, of beta-cell apoptosis and insulin processing, as well as the regulation of insulin release. For the basic researcher, this work is providing novel tools to explore fundamental molecular and cellular processes. For the clinician, these studies underscore the need to identify the genetic cause underlying each case. It is increasingly clear that the prognosis, therapeutic approach, and genetic counseling a physician provides must be tailored to a specific gene in order to provide the best medical care.

Clinical implications of a molecular genetic classification of monogenic beta-cell diabetes

Monogenic diabetes resulting from mutations that primarily reduce beta-cell function accounts for 1-2% of diabetes cases, although it is often misdiagnosed as either type 1 or type 2 diabetes. Knowledge of the genetic etiology of diabetes enables more-appropriate treatment, better prediction of disease progression, screening of family members and genetic counseling. We propose that the old clinical classifications of maturity-onset diabetes of the young and neonatal diabetes are obsolete and that specific genetic etiologies should be sought in four broad clinical situations because of their specific treatment implications. Firstly, diabetes diagnosed before 6 months of age frequently results from mutation of genes that encode Kir6.2 (ATP-sensitive inward rectifier potassium channel) or sulfonylurea receptor 1 subunits of an ATP-sensitive potassium channel, and improved glycemic control can be achieved by treatment with high-dose sulfonylureas rather than insulin. Secondly, patients with stable, mild fasting hyperglycemia detected particularly when they are young could have a glucokinase mutation and might not require specific treatment. Thirdly, individuals with familial, young-onset diabetes that does not fit with either type 1 or type 2 diabetes might have mutations in the transcription factors HNF-1alpha (hepatocyte nuclear factor 1-alpha) or HNF-4alpha, and can be treated with low-dose sulfonylureas. Finally, extrapancreatic features, such as renal disease (caused by mutations in HNF-1beta) or deafness (caused by a mitochondrial m.3243A>G mutation), usually require early treatment with insulin.

Epidemiology, clinical and complications profile of diabetes in Saudi Arabia: a review

Diabetes mellitus is emerging as a major public health problem in Saudi Arabia in parallel with the worldwide diabetes pandemic, which is having a particular impact upon the Middle East and the third world. This pandemic has accompanied the adoption of a modern lifestyle and the abandonment of a traditional lifestyle, with a resultant increase in rates of obesity and other chronic non-communicable diseases. The indigenous Saudi population seems to have a special genetic predisposition to develop type 2 diabetes, which is further amplified by a rise in obesity rates, a high rate of consanguinity and the presence of other variables of the insulin resistance syndrome. We highlight the epidemiology, clinical and complications profiles of diabetes in Saudi people. Diabetes is well studied in Saudi Arabia; however, there seems to be little research in the area of education and health care delivery. This is of paramount importance to offset the perceived impact on health care delivery services, to lessen chronic diabetes complications, and to reduce the expected morbidity and mortality from diabetes.

Mutations in GLIS3 are responsible for a rare syndrome with neonatal diabetes mellitus and congenital hypothyroidism

We recently described a new neonatal diabetes syndrome associated with congenital hypothyroidism, congenital glaucoma, hepatic fibrosis and polycystic kidneys. Here, we show that this syndrome results from mutations in GLIS3, encoding GLI similar 3, a recently identified transcription factor. In the original family, we identified a frameshift mutation predicted to result in a truncated protein. In two other families with an incomplete syndrome, we found that affected individuals harbor deletions affecting the 11 or 12 5'-most exons of the gene. The absence of a major transcript in the pancreas and thyroid (deletions from both families) and an eye-specific transcript (deletion from one family), together with residual expression of some GLIS3 transcripts, seems to explain the incomplete clinical manifestations in these individuals. GLIS3 is expressed in the pancreas from early developmental stages, with greater expression in beta cells than in other pancreatic tissues. These results demonstrate a major role for GLIS3 in the development of pancreatic beta cells and the thyroid, eye, liver and kidney.