The p.Pro2232Leu variant in the ChEL domain of thyroglobulin gene causes intracellular transport disorder and congenital hypothyroidism.

Thyroglobulin (TG), the predominant glycoprotein of the thyroid gland, functions as matrix protein in thyroid hormonegenesis. TG deficiency results in thyroid dyshormonogenesis. These variants produce a heterogeneous spectrum of congenital goitre, with an autosomal recessive mode of inheritance. The purpose of this study was to identify and functionally characterize new variants in the TG gene in order to increase the understanding of the molecular mechanisms responsible for thyroid dyshormonogenesis. A total of four patients from two non-consanguineous families with marked alteration of TG synthesis were studied. The two families were previously analysed in our laboratory, only one deleterious allele, in each one, was detected after sequencing the TG gene (c.2359 C > T [p.Arg787*], c.5560 G > T [p.Glu1854*]). These findings were confirmed in the present studies by Next-Generation Sequencing. The single nucleotide coding variants of the TG gene were then analyzed to predict the possible variant causing the disease. The p.Pro2232Leu (c.6695 C > T), identified in both families, showing a low frequency population in gnomAD v2.1.1 database and protein homology, amino acid prediction, and 3D modeling analysis predict a potential pathogenic effect of this variant. We also transiently express p.Pro2232Leu in a full-length rat TG cDNA clone and confirmed that this point variant was sufficient to cause intracellular retention of mutant TG in HEK293T cells. Consequently, each family carried a compound heterozygous for p.Arg787*/p.Pro2232Leu or p.Glu1854*/p.Pro2232Leu variants. In conclusion, our results confirm the pathophysiological importance of altered TG folding as a consequence of missense variants located in the ChEL domain of TG.

Barriers to Physical Activity in Children and Adults Living With Type 1 Diabetes: A Complex Link With Real-life Glycemic Excursions.

OBJECTIVES: Ever since the first research on barriers to physical activity (PA) highlighting fear of hypoglycemia as a major barrier, many studies have attempted to understand their demographic and behavioural determinants. However, no research has been conducted on whether these perceived barriers toward PA are based on real-life-experienced adverse glycemic effects of exercise. METHODS: Sixty-two adults and 53 children/adolescents living with type 1 diabetes, along with their parents, completed the Barriers to Physical Activity in Type 1 Diabetes-1 (BAPAD-1) questionnaire on barriers to PA. Continuous glucose-monitoring data were collected during 1 week of everyday life for 26 adults and 33 children/adolescents. Multiple linear regressions were used to explore links between BAPAD-1 scores and glycemic excursions experienced during and after everyday-life self-reported PA sessions, controlling for behavioural (accelerometry) and demographic confounders. RESULTS: In children/adolescents, the more time spent in hypoglycemia on nights after PA sessions, the more they reported hypoglycemic risk as a barrier (ß=+0.365, p=0.034). Conversely, in adults, the higher the proportion of PA sessions accompanied by a drop in blood glucose, the less hypoglycemia was a barrier (ß=-0.046, p=0.004). In parents, BAPAD-1 scores were unrelated to children/adolescents' everyday-life exercise-induced hypo/hyperglycemia. CONCLUSIONS: In children/adolescents, fear of hypoglycemia was predominant in those exposed to nocturnal hypoglycemia associated with PA sessions. In adults, fewer barriers may mean they accept a bigger drop in their glycemia during PA. This shows the importance of finding and promoting age-specific solutions to prevent exercise-induced hypoglycemia.

SHP2 drives inflammation-triggered insulin resistance by reshaping tissue macrophage populations.

Insulin resistance is a key event in type 2 diabetes onset and a major comorbidity of obesity. It results from a combination of fat excess-triggered defects, including lipotoxicity and metaflammation, but the causal mechanisms remain difficult to identify. Here, we report that hyperactivation of the tyrosine phosphatase SHP2 found in Noonan syndrome (NS) led to an unsuspected insulin resistance profile uncoupled from altered lipid management (for example, obesity or ectopic lipid deposits) in both patients and mice. Functional exploration of an NS mouse model revealed this insulin resistance phenotype correlated with constitutive inflammation of tissues involved in the regulation of glucose metabolism. Bone marrow transplantation and macrophage depletion improved glucose homeostasis and decreased metaflammation in the mice, highlighting a key role of macrophages. In-depth analysis of bone marrow-derived macrophages in vitro and liver macrophages showed that hyperactive SHP2 promoted a proinflammatory phenotype, modified resident macrophage homeostasis, and triggered monocyte infiltration. Consistent with a role of SHP2 in promoting inflammation-driven insulin resistance, pharmaceutical SHP2 inhibition in obese diabetic mice improved insulin sensitivity even better than conventional antidiabetic molecules by specifically reducing metaflammation and alleviating macrophage activation. Together, these results reveal that SHP2 hyperactivation leads to inflammation-triggered metabolic impairments and highlight the therapeutical potential of SHP2 inhibition to ameliorate insulin resistance.

Loss-of-function mutations in MRAP2 are pathogenic in hyperphagic obesity with hyperglycemia and hypertension.

The G-protein-coupled receptor accessory protein MRAP2 is implicated in energy control in rodents, notably via the melanocortin-4 receptor1. Although some MRAP2 mutations have been described in people with obesity1-3, their functional consequences on adiposity remain elusive. Using large-scale sequencing of MRAP2 in 9,418 people, we identified 23 rare heterozygous variants associated with increased obesity risk in both adults and children. Functional assessment of each variant shows that loss-of-function MRAP2 variants are pathogenic for monogenic hyperphagic obesity, hyperglycemia and hypertension. This contrasts with other monogenic forms of obesity characterized by excessive hunger, including melanocortin-4 receptor deficiency, that present with low blood pressure and normal glucose tolerance4. The pleiotropic metabolic effect of loss-of-function mutations in MRAP2 might be due to the failure of different MRAP2-regulated G-protein-coupled receptors in various tissues including pancreatic islets.

CoDE-seq, an augmented whole-exome sequencing, enables the accurate detection of CNVs and mutations in Mendelian obesity and intellectual disability.

OBJECTIVE: The molecular diagnosis of extreme forms of obesity, in which accurate detection of both copy number variations (CNVs) and point mutations, is crucial for an optimal care of the patients and genetic counseling for their families. Whole-exome sequencing (WES) has benefited considerably this molecular diagnosis, but its poor ability to detect CNVs remains a major limitation. We aimed to develop a method (CoDE-seq) enabling the accurate detection of both CNVs and point mutations in one step. METHODS: CoDE-seq is based on an augmented WES method, using probes distributed uniformly throughout the genome. CoDE-seq was validated in 40 patients for whom chromosomal DNA microarray was available. CNVs and mutations were assessed in 82 children/young adults with suspected Mendelian obesity and/or intellectual disability and in their parents when available (ntotal = 145). RESULTS: CoDE-seq not only detected all of the 97 CNVs identified by chromosomal DNA microarrays but also found 84 additional CNVs, due to a better resolution. When compared to CoDE-seq and chromosomal DNA microarrays, WES failed to detect 37% and 14% of CNVs, respectively. In the 82 patients, a likely molecular diagnosis was achieved in >30% of the patients. Half of the genetic diagnoses were explained by CNVs while the other half by mutations. CONCLUSIONS: CoDE-seq has proven cost-efficient and highly effective as it avoids the sequential genetic screening approaches currently used in clinical practice for the accurate detection of CNVs and point mutations.

Molecular analysis of thyroglobulin mutations found in patients with goiter and hypothyroidism.

Thyroid dyshormonogenesis due to thyroglobulin (TG) gene mutations have an estimated incidence of approximately 1 in 100,000 newborns. The clinical spectrum ranges from euthyroid to mild or severe hypothyroidism. Up to now, one hundred seventeen deleterious mutations in the TG gene have been identified and characterized. The purpose of the present study was to identify and characterize new mutations in the TG gene. We report eight patients from seven unrelated families with goiter, hypothyroidism and low levels of serum TG. All patients underwent clinical, biochemical and image evaluation. Sequencing of DNA, genotyping, as well as bioinformatics analysis were performed. Molecular analyses revealed three novel inactivating TG mutations: c.5560G>T [p.E1835*], c.7084G>C [p.A2343P] and c.7093T>C [p.W2346R], and four previously reported mutations: c.378C>A [p.Y107*], c.886C>T [p.R277*], c.1351C>T [p.R432*] and c.7007G>A [p.R2317Q]. Two patients carried homozygous mutations (p.R277*/p.R277*, p.W2346R/p.W2346R), four were compound heterozygous mutations (p.Y107*/p.R277* (two unrelated patients), p.R432*/p.A2343P, p.Y107*/p.R2317Q) and two siblings from another family had a single p.E1835* mutated allele. Additionally, we include the analysis of 48 patients from 31 unrelated families with TG mutations identified in our present and previous studies. Our observation shows that mutations in both TG alleles were found in 27 families (9 as homozygote and 18 as heterozygote compound), whereas in the remaining four families only one mutated allele was detected. The majority of the detected mutations occur in exons 4, 7, 38 and 40. 28 different mutations were identified, 33 of the 96 TG alleles encoded the change p.R277*. In conclusion, our results confirm the genetic heterogeneity of TG defects and the pathophysiological importance of the predicted TG misfolding and therefore thyroid hormone formation as a consequence of truncated TG proteins and/or missense mutations located within its ACHE-like domain.

Randomized, double-blind, placebo-controlled dose-finding study of the dipeptidyl peptidase-4 inhibitor linagliptin in pediatric patients with type 2 diabetes.

OBJECTIVE: To identify the dose of the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin in pediatric patients with type 2 diabetes (T2D). METHODS: Double-blind, randomized, controlled parallel group study comparing linagliptin 1 and 5 mg once daily, with placebo in 39 patients with T2D aged 10 to below 18 years. The primary efficacy endpoint was the change from baseline in glycated hemoglobin (HbA1c) after 12 weeks of treatment. The key pharmacodynamic endpoint was DPP-4 inhibition during steady-state. RESULTS: Compared to placebo, there was a dose-dependent reduction in mean HbA1c of 0.48% and 0.63% with linagliptin 1 and 5 mg, respectively, associated with corresponding declines in mean fasting plasma glucose (FPG) of 5.6 and 34.2 mg/dL. Median DPP-4 inhibition was 38% with linagliptin 1 mg and 79% with linagliptin 5 mg. Geometric mean trough levels of linagliptin were 3.80 and 7.42 nmol/L in the 1 and 5 mg groups, respectively; levels that were slightly higher than in adult patients with T2D that were most likely caused by higher plasma DPP-4 concentrations in the study population. There were no drug-related adverse events during treatment with either dose of linagliptin. CONCLUSIONS: Linagliptin was well tolerated and induced dose-dependent DPP-4 inhibition that was accompanied by corresponding reductions in HbA1c and FPG levels in young people with T2D. The results are consistent with the clinical efficacy and safety profile that have been reported for linagliptin in adult patients with T2D, favoring linagliptin 5 mg over 1 mg.

Relationship between salivary/pancreatic amylase and body mass index: a systems biology approach.

BACKGROUND: Salivary (AMY1) and pancreatic (AMY2) amylases hydrolyze starch. Copy number of AMY1A (encoding AMY1) was reported to be higher in populations with a high-starch diet and reduced in obese people. These results based on quantitative PCR have been challenged recently. We aimed to re-assess the relationship between amylase and adiposity using a systems biology approach. METHODS: We assessed the association between plasma enzymatic activity of AMY1 or AMY2, and several metabolic traits in almost 4000 French individuals from D.E.S.I.R. longitudinal study. The effect of the number of copies of AMY1A (encoding AMY1) or AMY2A (encoding AMY2) measured through droplet digital PCR was then analyzed on the same parameters in the same study. A Mendelian randomization analysis was also performed. We subsequently assessed the association between AMY1A copy number and obesity risk in two case-control studies (5000 samples in total). Finally, we assessed the association between body mass index (BMI)-related plasma metabolites and AMY1 or AMY2 activity. RESULTS: We evidenced strong associations between AMY1 or AMY2 activity and lower BMI. However, we found a modest contribution of AMY1A copy number to lower BMI. Mendelian randomization identified a causal negative effect of BMI on AMY1 and AMY2 activities. Yet, we also found a significant negative contribution of AMY1 activity at baseline to the change in BMI during the 9-year follow-up, and a significant contribution of AMY1A copy number to lower obesity risk in children, suggesting a bidirectional relationship between AMY1 activity and adiposity. Metabonomics identified a BMI-independent association between AMY1 activity and lactate, a product of complex carbohydrate fermentation. CONCLUSIONS: These findings provide new insights into the involvement of amylase in adiposity and starch metabolism.

Associations Between Type 2 Diabetes-Related Genetic Scores and Metabolic Traits, in Obese and Normal-Weight Youths.

CONTEXT: Young-onset obesity is strongly associated with the early development of type 2 diabetes (T2D). Genetic risk scores (GRSs) related to T2D might help predicting the early impairment of glucose homeostasis in obese youths. OBJECTIVE: Our objective was to investigate the contributions of four GRSs (associated with: T2D [GRS-T2D], beta-cell function [GRS-ß], insulin resistance [GRS-IR], and body mass index) to the variation of traits derived from oral glucose tolerance test (OGTT) in obese and normal-weight children and young adults. DESIGN: This was a cross-sectional association study. PATIENTS: A total of 1076 obese children/adolescents (age = 11.4 ± 2.8 years) and 1265 normal-weight young volunteers (age = 21.1 ± 4.4 years) of European ancestry were recruited from pediatric obesity clinics and general population, respectively. INTERVENTION: Standard OGTT was the intervention in this study. MAIN OUTCOME MEASURES: Associations between GRSs and OGTT-derived traits including fasting glucose and insulin, insulinogenic index, insulin sensitivity index, disposition index (DI) and associations between GRSs and pre-diabetic conditions were measured. RESULTS: GRS-ß significantly associated with fasting glucose (ß = 0.019; P = 3.5 × 10-4) and DI (ß = -0.031; P = 8.9 × 10-4, last quartile 18% lower than first) in obese children, and nominally associated with fasting glucose (ß = 0.009; P = 0.017) and DI (ß = -0.030; P = 1.1 × 10-3, last quartile 11% lower than first) in normal-weight youths. GRS-T2D showed weaker contribution to fasting glucose and DI compared to GRS-ß, in both obese and normal-weight youths. GRS associated with insulin resistance and GRS associated with body mass index did not associate with any traits. None of the GRSs associated with prediabetes, which affected only 4% of participants overall. CONCLUSION: Single nucleotide polymorphisms identified by genome-wide association studies to influence beta-cell function were associated with fasting glucose and indices of insulin secretion in youths, especially in obese children.

Growth patterns of patients with Noonan syndrome: correlation with age and genotype.

BACKGROUND: Growth patterns of patients with Noonan syndrome (NS) were established before the involved genes were identified. OBJECTIVE: The goal of this study was to compare growth parameters according to genotype in patients with NS. SUBJECTS AND METHODS: The study population included 420 patients (176 females and 244 males) harboring mutations in the PTPN11, SOS1, RAF1, or KRAS genes. NS-associated PTPN11 mutations (NS-PTPN11) and NS with multiple lentigines-associated PTPN11 mutations (NSML-PTPN11) were distinguished. Birth measures and height and body mass index (BMI) measures at 2, 5, 10 years, and adulthood were compared with the general population and between genotypes. RESULTS: Patients with NS were shorter at birth (mean birth length standard deviation score (SDS): -1.0 ± 1.4; P < 0.001) and throughout childhood than the healthy population, with height SDS being -2.1 ± 1.3 at 2 years, and -2.1 ± 1.2 at 5 and 10 years and adulthood (P < 0.001). At birth, patients with NS-PTPN11 were significantly shorter and thinner than patients with NSML-PTPN11, SOS1, or KRAS. Growth retardation was significantly less severe and less frequent at 2 years in patients with NSML-PTPN11 and SOS1 than in patients with NS-PTPN11 (P < 0.001 and P = 0.002 respectively). Patients with NS had lower BMI at 10 years (P < 0.001). No difference between genotypes was demonstrated. CONCLUSION: Determining the growth patterns of patients with NS according to genotype should better inform clinicians about the natural course of growth in NS so that they can optimize the follow-up and management of these patients.

Monocytes of Patients with Type 1 Diabetes Harbour Enterovirus RNA.

BACKGROUND: Intracellular enterovirus (EV) RNA was detected in blood of patients with type 1 diabetes (T1D). The presence of EV RNA in subsets of peripheral blood mononuclear cells (PBMCs) of patients, and the in vitro infection of these cells with an EV, was investigated. MATERIALS AND METHODS: Blood was collected from 42 patients with T1D, PBMCs were isolated and monocytes were purified. Interferon alpha (IFNα) mRNA and EV RNA were investigated using RT-PCR. Levels of IFNα in plasma were measured using an immunoassay. Cells were inoculated with Coxsackievirus B4 (CBV4) in vitro, and infection was assessed by indirect immunofluorescence (IFI). RESULTS: Interferon alpha mRNA was detected in blood and in monocytes of 12 of 42 patients with T1D, but not in monocyte-depleted PBMCs of the same individuals. Significant plasma levels of IFNα (≥ 5 IU/mL) were found in six patients. EV RNA was detected in whole blood and in monocytes of seven patients and negative-strand EV RNA was found in monocytes of 6 of them. When monocytes of patients with IFNα and/or EV RNA in their blood were inoculated with CVB4, the proportion of cells stained by an anti-VP1 antibody was 8.8 ± 1%, whereas no VP1 was detected in the monocytes of IFNα, EV RNA negative patients. Nevertheless, when CBV4 was mixed with plasma, VP1 was detected in monocytes of all patients with T1D (staining ranging from 12 to 36%). CONCLUSIONS: Our data indicate that monocytes of patients with T1D can harbor EV RNA and IFNα mRNA and can be infected with an EV in vitro.

Contribution of the low-frequency, loss-of-function p.R270H mutation in FFAR4 (GPR120) to increased fasting plasma glucose levels.

BACKGROUND: We previously reported that the low-frequency, loss-of-function variant p.R270H in FFAR4 encoding the lipid sensor GPR120 was associated with obesity. Gpr120-deficient mice develop obesity and both impaired fasting glucose and glucose intolerance under a high-fat diet. We aimed to assess the contribution of p.R270H to type 2 diabetes (T2D) risk and the variation of glucose-related traits. METHODS: We genotyped p.R270H in 8996 non-diabetic individuals (among whom 4523 had an oral glucose tolerance test (OGTT)) and in a T2D case-control study including 4725 cases and 4339 controls. The regression models were adjusted for age, sex and body mass index (BMI). RESULTS: We found a significant association between p.R270H and increased fasting glucose levels (ß=0.092±0.05 mmol/L; p=4.13×10(-4)). Furthermore, p.R270H nominally contributed to decreased homeostasis model of pancreatic ß-cell function (HOMA-B; ß=-0.090±0.06; p=6.01×10(-3)). Despite a high statistical power, we did not find any significant association between p.R270H and T2D risk or the variation of fasting insulin levels, the homeostasis model of insulin resistance or OGTT-derived indices. CONCLUSIONS: These results suggest that the low-frequency p.R270H variant which inhibits GPR120 activity might influence fasting glucose levels in a normal physiological range. This study does not exclude that other coding mutations in FFAR4 with stronger functional effect than p.R270H may be associated with T2D.

Low copy number of the salivary amylase gene predisposes to obesity.

Common multi-allelic copy number variants (CNVs) appear enriched for phenotypic associations compared to their biallelic counterparts. Here we investigated the influence of gene dosage effects on adiposity through a CNV association study of gene expression levels in adipose tissue. We identified significant association of a multi-allelic CNV encompassing the salivary amylase gene (AMY1) with body mass index (BMI) and obesity, and we replicated this finding in 6,200 subjects. Increased AMY1 copy number was positively associated with both amylase gene expression (P = 2.31 × 10(-14)) and serum enzyme levels (P < 2.20 × 10(-16)), whereas reduced AMY1 copy number was associated with increased BMI (change in BMI per estimated copy = -0.15 (0.02) kg/m(2); P = 6.93 × 10(-10)) and obesity risk (odds ratio (OR) per estimated copy = 1.19, 95% confidence interval (CI) = 1.13-1.26; P = 1.46 × 10(-10)). The OR value of 1.19 per copy of AMY1 translates into about an eightfold difference in risk of obesity between subjects in the top (copy number > 9) and bottom (copy number < 4) 10% of the copy number distribution. Our study provides a first genetic link between carbohydrate metabolism and BMI and demonstrates the power of integrated genomic approaches beyond genome-wide association studies.

Loss-of-function mutations in SIM1 contribute to obesity and Prader-Willi-like features.

Sim1 haploinsufficiency in mice induces hyperphagic obesity and developmental abnormalities of the brain. In humans, abnormalities in chromosome 6q16, a region that includes SIM1, were reported in obese children with a Prader-Willi-like syndrome; however, SIM1 involvement in obesity has never been conclusively demonstrated. Here, SIM1 was sequenced in 44 children with Prader-Willi-like syndrome features, 198 children with severe early-onset obesity, 568 morbidly obese adults, and 383 controls. We identified 4 rare variants (p.I128T, p.Q152E, p.R581G, and p.T714A) in 4 children with Prader-Willi-like syndrome features (including severe obesity) and 4 other rare variants (p.T46R, p.E62K, p.H323Y, and p.D740H) in 7 morbidly obese adults. By assessing the carriers' relatives, we found a significant contribution of SIM1 rare variants to intra-family risk for obesity. We then assessed functional effects of the 8 substitutions on SIM1 transcriptional activities in stable cell lines using luciferase gene reporter assays. Three mutations showed strong loss-of-function effects (p.T46R, p.H323Y, and p.T714A) and were associated with high intra-family risk for obesity, while the variants with mild or no effects on SIM1 activity were not associated with obesity within families. Our genetic and functional studies demonstrate a firm link between SIM1 loss of function and severe obesity associated with, or independent of, Prader-Willi-like features.

Radiographic features of osteogenesis imperfecta.

BACKGROUND: Osteogenesis imperfecta (OI), commonly called "brittle bone disease", is a genetic disorder characterised by increased bone fragility and decreased bone density due to quantitative and/or qualitative abnormalities of type I collagen. Different types of OI exist, from mild to severe; they may lead to death, multiple bone fractures, skeletal deformity and short stature. METHODS: Severe cases are usually diagnosed before birth and may incite the parents to choose therapeutic abortion, whereas milder cases are much more difficult to diagnose and may be sometimes confused with non-accidental injury (NAI) ("child abuse") in young children. Whatever the degree of severity, conventional radiography still remains the mainstay in diagnosing OI. RESULTS: The prognosis of this disorder has changed in the last few years thanks to biphosphonate therapy. CONCLUSION: The aim of this pictorial review is to illustrate the radiographic manifestations of OI, including in children receiving biphosphonates, and to outline specific patterns that help differentiate OI from NAI when necessary. KEY POINTS: • The main radiographic features of OI are osteopenia, bone fractures and bone deformities. • Some radiographic features depend on the type of OI or may be encountered with biphosphonates.

How to diagnose a lipodystrophy syndrome.

The spectrum of adipose tissue diseases ranges from obesity to lipodystrophy, and is accompanied by insulin resistance syndrome, which promotes the occurrence of type 2 diabetes, dyslipidemia and cardiovascular complications. Lipodystrophy refers to a group of rare diseases characterized by the generalized or partial absence of adipose tissue, and occurs with or without hypertrophy of adipose tissue in other sites. They are classified as being familial or acquired, and generalized or partial. The genetically determined partial forms usually occur as Dunnigan syndrome, which is a type of laminopathy that can also manifest as muscle, cardiac, neuropathic or progeroid involvement. Gene mutations encoding for PPAR-gamma, Akt2, CIDEC, perilipin and the ZMPSTE 24 enzyme are much more rare. The genetically determined generalized forms are also very rare and are linked to mutations of seipin AGPAT2, FBN1, which is accompanied by Marfan syndrome, or of BANF1, which is characterized by a progeroid syndrome without insulin resistance and with early bone complications. Glycosylation disorders are sometimes involved. Some genetically determined forms have recently been found to be due to autoinflammatory syndromes linked to a proteasome anomaly (PSMB8). They result in a lipodystrophy syndrome that occurs secondarily with fever, dermatosis and panniculitis. Then there are forms that are considered to be acquired. They may be iatrogenic (protease inhibitors in HIV patients, glucocorticosteroids, insulin, graft-versus-host disease, etc.), related to an immune system disease (sequelae of dermatopolymyositis, autoimmune polyendocrine syndromes, particularly associated with type 1 diabetes, Barraquer-Simons and Lawrence syndromes), which are promoted by anomalies of the complement system. Finally, lipomatosis is currently classified as a painful form (adiposis dolorosa or Dercum's disease) or benign symmetric multiple form, also known as Launois-Bensaude syndrome or Madelung's disease, which are sometimes related to mitochondrial DNA mutations, but are usually promoted by alcohol. In addition to the medical management of metabolic syndrome and the sometimes surgical treatment of lipodystrophy, recombinant leptin provides hope for genetically determined lipodystrophy syndromes, whereas modifications in antiretroviral treatment and tesamorelin, a GHRH analog, is effective in the metabolic syndrome of HIV patients. Other therapeutic options will undoubtedly be developed, dependent on pathophysiological advances, which today tend to classify genetically determined lipodystrophy as being related to laminopathy or to lipid droplet disorders.

Screening of MAMLD1 mutations in 70 children with 46,XY DSD: identification and functional analysis of two new mutations.

More than 50% of children with severe 46,XY disorders of sex development (DSD) do not have a definitive etiological diagnosis. Besides gonadal dysgenesis, defects in androgen biosynthesis, and abnormalities in androgen sensitivity, the Mastermind-like domain containing 1 (MAMLD1) gene, which was identified as critical for the development of male genitalia, may be implicated. The present study investigated whether MAMLD1 is implicated in cases of severe 46,XY DSD and whether routine sequencing of MAMLD1 should be performed in these patients.Seventy children with severe non-syndromic 46,XY DSD of unknown etiology were studied. One hundred and fifty healthy individuals were included as controls. Direct sequencing of the MAMLD1, AR, SRD5A2 and NR5A1 genes was performed. The transactivation function of the variant MAMLD1 proteins was quantified by the luciferase method.TWO NEW MUTATIONS WERE IDENTIFIED: p.S143X (c.428C>A) in a patient with scrotal hypospadias with microphallus and p.P384L (c.1151C>T) in a patient with penile hypospadias with microphallus. The in vitro functional study confirmed no residual transactivating function of the p.S143X mutant and a significantly reduced transactivation function of the p.P384L protein (p = 0.0032). The p.P359S, p.N662S and p.H347Q variants are also reported with particularly high frequency of the p.359T- p.662G haplotype in the DSD patients.Severe undervirilization in XY newborns can reveal mutations of MAMLD1. MAMLD1 should be routinely sequenced in these patients with otherwise normal AR, SRD5A2 and NR5A1genes.

Identification by array-Comparative Genomic Hybridization (array-CGH) of a large deletion of luteinizing hormone receptor gene combined with a missense mutation in a patient diagnosed with a 46,XY disorder of sex development and application to prenatal diagnosis.

This paper reports the case of an infant presenting with sexual ambiguity at birth. The child presented with labia majora synechia, thready genital tubercle and perineal hypospadias. The karyotype was 46,XY. Low testosterone levels with no response to hCG administration, associated with high LH level for her age, high FSH level, high inhibin B levels and normal AMH indicated a lack of LH receptivity and prompted us to screen the LHCGR gene for mutations. A previously described missense mutation (p.Cys131Arg) was identified at homozygous state in the propositus and at heterozygous state in the mother. This variation, however, was not found in the father. Our attention was drawn by the presence of several single nucleotide polymorphisms (SNPs), identified at homozygous state without any paternal contribution from exon 1 to exon 10 of LHCGR, suggesting a paternal deletion. Array DNA analysis was performed revealing a large deletion extending from 61,493 to 135,344 bp and including the LHCGR gene. Adequate genetic counselling was provided. This paper describes the first application of prenatal diagnosis in LHCGR deficiency for 46,XY disorders of sex development with the subsequent delivery of a normal baby.

New insights into the pathogenesis of Beckwith-Wiedemann and Silver-Russell syndromes: contribution of small copy number variations to 11p15 imprinting defects.

The imprinted 11p15 region is organized in two domains, each of them under the control of its own imprinting control region (ICR1 for the IGF2/H19 domain and ICR2 for the KCNQ1OT1/CDKN1C domain). Disruption of 11p15 imprinting results in two fetal growth disorders with opposite phenotypes: the Beckwith-Wiedemann (BWS) and the Silver-Russell (SRS) syndromes. Various 11p15 genetic and epigenetic defects have been demonstrated in BWS and SRS. Among them, isolated DNA methylation defects account for approximately 60% of patients. To investigate whether cryptic copy number variations (CNVs) involving only part of one of the two imprinted domains account for 11p15 isolated DNA methylation defects, we designed a single nucleotide polymorphism array covering the whole 11p15 imprinted region and genotyped 185 SRS or BWS cases with loss or gain of DNA methylation at either ICR1 or ICR2. We describe herein novel small gain and loss CNVs in six BWS or SRS patients, including maternally inherited cis-duplications involving only part of one of the two imprinted domains. We also show that ICR2 deletions do not account for BWS with ICR2 loss of methylation and that uniparental isodisomy involving only one of the two imprinted domains is not a mechanism for SRS or BWS.

Two new Loci for body-weight regulation identified in a joint analysis of genome-wide association studies for early-onset extreme obesity in French and german study groups.

Meta-analyses of population-based genome-wide association studies (GWAS) in adults have recently led to the detection of new genetic loci for obesity. Here we aimed to discover additional obesity loci in extremely obese children and adolescents. We also investigated if these results generalize by estimating the effects of these obesity loci in adults and in population-based samples including both children and adults. We jointly analysed two GWAS of 2,258 individuals and followed-up the best, according to lowest p-values, 44 single nucleotide polymorphisms (SNP) from 21 genomic regions in 3,141 individuals. After this DISCOVERY step, we explored if the findings derived from the extremely obese children and adolescents (10 SNPs from 5 genomic regions) generalized to (i) the population level and (ii) to adults by genotyping another 31,182 individuals (GENERALIZATION step). Apart from previously identified FTO, MC4R, and TMEM18, we detected two new loci for obesity: one in SDCCAG8 (serologically defined colon cancer antigen 8 gene; p = 1.85x10(-8) in the DISCOVERY step) and one between TNKS (tankyrase, TRF1-interacting ankyrin-related ADP-ribose polymerase gene) and MSRA (methionine sulfoxide reductase A gene; p = 4.84x10(-7)), the latter finding being limited to children and adolescents as demonstrated in the GENERALIZATION step. The odds ratios for early-onset obesity were estimated at approximately 1.10 per risk allele for both loci. Interestingly, the TNKS/MSRA locus has recently been found to be associated with adult waist circumference. In summary, we have completed a meta-analysis of two GWAS which both focus on extremely obese children and adolescents and replicated our findings in a large followed-up data set. We observed that genetic variants in or near FTO, MC4R, TMEM18, SDCCAG8, and TNKS/MSRA were robustly associated with early-onset obesity. We conclude that the currently known major common variants related to obesity overlap to a substantial degree between children and adults.