Svetlana Ten

Prevalence of vitamin D insufficiency in obese children and adolescents.

OBJECTIVE Recent studies have shown a broad prevalence of vitamin D deficiency in adults. Serum 25-hydroxyvitamin D (25-OHD) levels were reported to be inversely related to body mass index (BMI) and body fat content and correlated directly with hypertension, degree of insulin resistance and progression to diabetes mellitus. We sought to determine the prevalence of vitamin D insufficiency and markers of metabolic syndrome in an obese pediatric population. METHODS Charts of 217 obese (weight >95th percentile for age and sex) children (118 females, 99 males; mean BMI 32.2 +/- 6.4 kg/m2; mean age 12.9 2 5.5; age range 7-18 years) who had received a standard physical examination at the pediatric endocrine clinic of the Infants and Childrens Hospital of Brooklyn at Maimonides, Brooklyn, NY, were retrospectively analyzed. Data obtained included age, sex, weight, BMI, height and systolic and diastolic blood pressure. The routine bloodwork panel for obesity at our pediatric endocrine facility includes fasting 25-OHD, total cholesterol, high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), triglycerides, ALT, AST, thyroid stimulating hormone (TSH), total T4, and insulin and glucose. Insulin sensitivity as calculated by quantitative insulin-sensitivity check index (QUICKI = 1/[log(I0) + log(G0)], where I0 is fasting insulin and G0 is fasting glucose) was computed following the visit. RESULTS Overall, 55.2% of patients were vitamin D insufficient (25-OHD <20 ng/ml). Severely low vitamin D levels (25-OHD < or =10 ng/ml) were seen in 21.6% of 217 patients, which represents almost half of the insufficient group. In the 25-OHD <20 ng/ml group age, BMI, and SBP were significantly higher than in the 25-OHD 220 ng/ml group, while QUICKI (<0.35 is consistent with insulin resistance) was borderline low in the <20 ng/ml group. HDL-C was significantly lower in the 25-OHD < or =10 ng/ml group. The 25-OHD levels correlated negatively with BMI and positively with HDL-C. No other findings were significant. CONCLUSION More than half of the obese children had vitamin D levels <20 ng/ml with equal gender distribution. Vitamin D insufficiency was associated with increased age, BMI, and SBP, and decreased HDL-C.

Expanding the Spectrum of Mutations in GH1 and GHRHR: Genetic Screening in a Large Cohort of Patients with Congenital Isolated Growth Hormone Deficiency

CONTEXT It is estimated that 3-30% of cases with isolated GH deficiency (IGHD) have a genetic etiology, with a number of mutations being reported in GH1 and GHRHR. The aim of our study was to genetically characterize a cohort of patients with congenital IGHD and analyze their characteristics. PATIENTS AND METHODS A total of 224 patients (190 pedigrees) with IGHD and a eutopic posterior pituitary were screened for mutations in GH1 and GHRHR. To explore the possibility of an association of GH1 abnormalities with multiple pituitary hormone deficiencies, we have screened 62 patients with either multiple pituitary hormone deficiencies (42 pedigrees), or IGHD with an ectopic posterior pituitary (21 pedigrees). RESULTS Mutations in GH1 and GHRHR were identified in 41 patients from 21 pedigrees (11.1%), with a higher prevalence in familial cases (38.6%). These included previously described and novel mutations in GH1 (C182X, G120V, R178H, IVS3+4nt, a>t) and GHRHR (W273S, R94L, R162W). Autosomal dominant, type II IGHD was the commonest form (52.4%), followed by type IB (42.8%) and type IA (4.8%). Patients with type II IGHD had highly variable phenotypes. There was no difference in the endocrinology or magnetic resonance imaging appearance between patients with and without mutations, although those with mutations presented with more significant growth failure (height, -4.7 +/- 1.6 SDS vs. -3.4 +/- 1.7 SDS) (P = 0.001). There was no apparent difference between patients with mutations in GH1 and GHRHR. CONCLUSIONS IGHD patients with severe growth failure and a positive family history should be screened for genetic mutations; the evolving endocrinopathy observed in some of these patients suggests the need for long-term follow-up.

Roles of the LHX3 and LHX4 LIM-Homeodomain Factors in Pituitary Development

The LHX3 and LHX4 LIM-homeodomain transcription factors play essential roles in pituitary gland and nervous system development. Mutations in the genes encoding these regulatory proteins are associated with combined hormone deficiency diseases in humans and animal models. Patients with these diseases have complex syndromes involving short stature, and reproductive and metabolic disorders. Analyses of the features of these diseases and the biochemical properties of the LHX3 and LHX4 proteins will facilitate a better understanding of the molecular pathways that regulate the development of the specialized hormone-secreting cells of the mammalian anterior pituitary gland.

The clinical and molecular heterogeneity of 17βHSD-3 enzyme deficiency.

17-β-hydroxysteroid dehydrogenase type 3 (17βHSD-3) deficiency is a rare, but frequently misdiagnosed autosomal recessive cause of 46,XY disorder of sex development (DSD). 17βHSD-3 enzyme is present almost exclusively in the testes and converts Δ4-androstenedione (Δ4) to testosterone (T). The diagnosis can be easily missed in early childhood as the clinical presentation may be subtle. Any young girl with an inguinal hernia, mild clitoromegaly, single urethral opening or urogenital sinus should raise suspicion. If not diagnosed early, patients present with severe virilization and primary amenorrhea in adolescence and may undergo a change from a female to male gender role. A low T/Δ4 ratio on baseline or hCG (human chorionic gonadotropin)-stimulated testing is suggestive of 17βHSD-3 deficiency. The diagnosis can be confirmed with molecular genetic studies. This review summarizes the clinical presentations, reported mutations, diagnosis, treatment and clinical course of this disorder. The Arg80 site in exon 3 is the most common location of repeated mutations and can be considered a hot spot in certain Arab populations.

Radioimmunoassay for autoantibodies against interferon omega; its use in the diagnosis of autoimmune polyendocrine syndrome type I

Patients with the autoimmune polyendocrine syndrome I (APS I) have high titers of neutralizing IgG autoantibodies against type I interferons (IFNs), in particular IFN-omega. Until now, the most specific assay has been the antiviral interferon neutralizing assay (AVINA), which has the drawbacks of requiring a cytolytic virus, being cumbersome and difficult to standardise. We have developed a fast and reliable immunoassay based on radiolabelled IFN-omega for quantifying anti-IFN-omega antibodies. Sera from 48 APS I patients were analysed together with those from 5 control groups. All sera from APS I patients were positive for anti-IFN-omega, while, except one serum, all sera from the controls were negative. This method has the advantage over bioassays that it is readily adapted to high throughput. It provides an alternative, sensitive and specific diagnostic test for APS I, and an ideal screening tool to precede mutational analyses of the AIRE gene in suspected APS I cases.

GnRH-Deficient Phenotypes in Humans and Mice with Heterozygous Variants in KISS1/Kiss1

CONTEXT KISS1 is a candidate gene for GnRH deficiency. OBJECTIVE Our objective was to identify deleterious mutations in KISS1. PATIENTS AND METHODS DNA sequencing and assessment of the effects of rare sequence variants (RSV) were conducted in 1025 probands with GnRH-deficient conditions. RESULTS Fifteen probands harbored 10 heterozygous RSV in KISS1 seen in less than 1% of control subjects. Of the variants that reside within the mature kisspeptin peptide, p.F117L (but not p.S77I, p.Q82K, p.H90D, or p.P110T) reduces inositol phosphate generation. Of the variants that lie within the coding region but outside the mature peptide, p.G35S and p.C53R (but not p.A129V) are predicted in silico to be deleterious. Of the variants that lie outside the coding region, one (g.1-3659C→T) impairs transcription in vitro, and another (c.1-7C→T) lies within the consensus Kozak sequence. Of five probands tested, four had abnormal baseline LH pulse patterns. In mice, testosterone decreases with heterozygous loss of Kiss1 and Kiss1r alleles (wild-type, 274 ± 99, to double heterozygotes, 69 ± 16 ng/dl; r(2) = 0.13; P = 0.03). Kiss1/Kiss1r double-heterozygote males have shorter anogenital distances (13.0 ± 0.2 vs. 15.6 ± 0.2 mm at P34, P < 0.001), females have longer estrous cycles (7.4 ± 0.2 vs. 5.6 ± 0.2 d, P < 0.01), and mating pairs have decreased litter frequency (0.59 ± 0.09 vs. 0.71 ± 0.06 litters/month, P < 0.04) and size (3.5 ± 0.2 vs. 5.4 ± 0.3 pups/litter, P < 0.001) compared with wild-type mice. CONCLUSIONS Deleterious, heterozygous RSV in KISS1 exist at a low frequency in GnRH-deficient patients as well as in the general population in presumably normal individuals. As in Kiss1(+/-)/Kiss1r(+/-) mice, heterozygous KISS1 variants in humans may work with other genetic and/or environmental factors to cause abnormal reproductive function.

Serum Levels of Soluble Tumor Necrosis Factor-α Receptor 2 are Linked to Insulin Resistance and Glucose Intolerance in Children

BACKGROUND Obesity and insulin resistance are increasingly common problems in children. Tumor necrosis factor-alpha (TNF-alpha) has important effects on lipid and glucose metabolism. This effect may be mediated through soluble TNF-alpha receptor 2 (sTNFR2). OBJECTIVE To investigate the relationship between insulin resistance and the TNF-alpha system in childhood obesity. CHILDREN AND METHODS Twenty-one obese and six non-obese children were studied. Body mass index (BMI) z-scores, percent body fat (PBF) and waist to hip ratio (WHR) were determined. Fasting serum levels of total cholesterol, HDL-cholesterol, LDL-cholesterol, TNF-alpha and sTNFR2 were measured. A standard 2-hour oral glucose tolerance test (dose of glucose: 1.75 g/kg, max. 75 g) was done. Insulin resistance (IR) was estimated by fasting plasma insulin, plasma insulin at 120 min, homeostasis model assessment (HOMA) and insulin area under the curve (AUC) from OGTT. Insulin sensitivity was estimated by oral glucose insulin sensitivity (OGIS120). RESULTS Among the obese participants, one child (5.2%) was found to have diabetes mellitus and four others (21.1%) impaired glucose tolerance (IGT). Obese children had significantly elevated sTNFR2 levels. Furthermore, the group of obese children with IGT and the patient with newly diagnosed diabetes mellitus together (n = 5) had significantly higher levels of serum sTNFR2 (2,865+/-320 pg/ml) than the rest of the obese (2,460+/-352 pg/ml; p = 0.016) or lean (1,969+/-362 pg/ml; p = 0.014) children. Serum sTNFR2 levels correlated positively with insulin AUC, HOMA IR, fasting plasma insulin, plasma insulin at 120 min, total cholesterol and LDL/ HDL ratio, and negatively with OGIS120. Multiple regression analysis revealed that age, WHR, sTNFR2 and LDL predicted 81% of the variability in glucose at 120 min. CONCLUSION sTNFR2 is a candidate marker of insulin resistance and glucose intolerance.

The prevalence of non-alcoholic fatty liver disease and metabolic syndrome in obese children.

Abstract Background and aim: In the context of present epidemic of childhood obesity, we aimed to fi nd the prevalence of nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS) in a cohort of obese children. Methodology: Retrospective chart analysis of 700 obese children was done for their anthropometric and biochemical investigations. Results: Some 15.4% (9.8% girls, 22% boys) subjects had NAFLD (ALT> 40 IU/L) after excluding other identifi able causes of liver dysfunction. Age, weight, TG, fasting serum insulin and HOMA-IR levels were higher in children with NAFLD. Twenty-eight percent children had MS. Children with NAFLD had an odds ratio of 2.65 for having MS (boys 4.6, girls 1.7). The prevalence of MS increased with age 5–9 years (21%), 10–16 years (30%), 17–20 years (35%). Conclusion: Given high prevalence of NAFLD and MS in obese children, childhood obesity should be seriously considered as a disease and not just a cosmetic issue.

Severe Mandibuloacral Dysplasia-Associated Lipodystrophy and Progeria in a Young Girl with a Novel Homozygous Arg527Cys LMNA Mutation

CONTEXT Mandibuloacral dysplasia (MAD) is a rare autosomal recessive progeroid syndrome due to mutations in genes encoding nuclear lamina proteins, lamins A/C (LMNA) or prelamin A processing enzyme, and zinc metalloproteinase (ZMPSTE24). OBJECTIVE The aim of the study was to investigate the underlying genetic and molecular basis of the phenotype of a 7-yr-old girl with MAD belonging to a consanguineous pedigree and with severe progeroid features and lipodystrophy. DESIGN AND PATIENT The patient developed mandibular hypoplasia during infancy and joint stiffness, skin thinning, and mottled hyperpigmentation at 15 months. Progressive clavicular hypoplasia, acroosteolysis, and severe loss of hair from the temporal and occipital areas were noticed at 3 yr. At 5 yr, cranial sutures were still open and lipodystrophy of the limbs was prominent. GH therapy from the ages of 3-7 yr did not improve the short stature. Severe joint contractures resulted in abnormal posture and decreased mobility. We studied her skin fibroblasts for nuclear morphology and immunoblotting and determined the in vitro effects of various pharmacological interventions on fibroblasts. RESULTS LMNA gene sequencing revealed a homozygous missense mutation, c.1579C>T, p.Arg527Cys. Immunoblotting of skin fibroblast lysate with lamin A/C antibody revealed no prelamin A accumulation. Immunofluorescence staining of the nuclei for lamin A/C in fibroblasts revealed marked nuclear morphological abnormalities. This abnormal phenotype could not be rescued with inhibitors of farnesyl transferase, geranylgeranyl transferase, or histone deacetylase. CONCLUSION Severe progeroid features in MAD could result from LMNA mutation, which does not lead to accumulation of prenylated lamin A or prelamin A.

Whole-Exome sequencing identifies novel LEPR mutations in individuals with severe early onset obesity

Obesity is a major public health problem that increases the risk for a broad spectrum of co‐morbid conditions. Despite evidence for a strong genetic contribution to susceptibility to obesity, previous efforts to discover the relevant genes using positional cloning have failed to account for most of the apparent genetic risk variance.