GNRH1 mutations in patients with idiopathic hypogonadotropic hypogonadism

Idiopathic hypogonadotropic hypogonadism (IHH) is a condition characterized by failure to undergo puberty in the setting of low sex steroids and low gonadotropins. IHH is due to abnormal secretion or action of the master reproductive hormone gonadotropin-releasing hormone (GnRH). Several genes have been found to be mutated in patients with IHH, yet to date no mutations have been identified in the most obvious candidate gene, GNRH1 itself, which encodes the preprohormone that is ultimately processed to produce GnRH. We screened DNA from 310 patients with normosmic IHH (nIHH) and 192 healthy control subjects for sequence changes in GNRH1. In 1 patient with severe congenital nIHH (with micropenis, bilateral cryptorchidism, and absent puberty), a homozygous frameshift mutation that is predicted to disrupt the 3 C-terminal amino acids of the GnRH decapeptide and to produce a premature stop codon was identified. Heterozygous variants not seen in controls were identified in 4 patients with nIHH: 1 nonsynonymous missense mutation in the eighth amino acid of the GnRH decapeptide, 1 nonsense mutation that causes premature termination within the GnRH-associated peptide (GAP), which lies C-terminal to the GnRH decapeptide within the GnRH precursor, and 2 sequence variants that cause nonsynonymous amino-acid substitutions in the signal peptide and in GnRH-associated peptide. Our results establish mutations in GNRH1 as a genetic cause of nIHH.

Congenital hypogonadotropic hypogonadism and constitutional delay of growth and puberty have distinct genetic architectures

OBJECTIVE

Congenital hypogonadotropic hypogonadism (CHH) and constitutional delay of growth and puberty (CDGP) represent rare and common forms of GnRH deficiency, respectively. Both CDGP and CHH present with delayed puberty, and the distinction between these two entities during early adolescence is challenging. More than 30 genes have been implicated in CHH, while the genetic basis of CDGP is poorly understood.

DESIGN

We characterized and compared the genetic architectures of CHH and CDGP, to test the hypothesis of a shared genetic basis between these disorders.

METHODS

Exome sequencing data were used to identify rare variants in known genes in CHH (n = 116), CDGP (n = 72) and control cohorts (n = 36 874 ExAC and n = 405 CoLaus).

RESULTS

Mutations in at least one CHH gene were found in 51% of CHH probands, which is significantly higher than in CDGP (7%, P = 7.6 × 10^-11) or controls (18%, P = 5.5 × 10^-12). Similarly, oligogenicity (defined as mutations in more than one gene) was common in CHH patients (15%) relative to CDGP (1.4%, P = 0.002) and controls (2%, P = 6.4 × 10^-7).

CONCLUSIONS

Our data suggest that CDGP and CHH have distinct genetic profiles, and this finding may facilitate the differential diagnosis in patients presenting with delayed puberty.

Epidemiology of type I diabetes mellitus in Switzerland: steep rise in incidence in under 5 year old children in the past decade

AIMS/HYPOTHESIS

In this nationwide prospective study we wanted to verify the trend of increasing diabetes incidence data from our earlier retrospective analysis of the military registry of Swiss men.

SUBJECTS AND METHODS

The data collection of newly diagnosed children in Switzerland at an age younger than 15 years started in 1991. The countrywide survey used a small questionnaire which was sent back to the study centre. The questionnaire was anonymous and contained: hospital of diagnosis, initials, sex, birth date, date of diagnosis, residence, country of citizenship, and responsible physician. General data on the population were taken from publications of the Swiss Federal Statistical Office.

RESULTS

A total of 941 children below the age of 15 years with newly diagnosed Type I (insulin-dependent) diabetes mellitus were collected (434 girls, 507 boys). The incidence in children aged 0 to 14 years rose significantly between 1991 and 1999 with a yearly average increase of 5.1%. In the age group 0 to 4 years a more than four-fold increase in incidence from 2.4/100,000 per year to 10.5/100,000 per year (p = 0.0002) was recorded, whereas the age-specific incidence in the 5 to 9-year-old and 10 to 14-year-old children did not change during the data collection period. The incidence was significantly higher in boys than in girls, whereas no difference was found between rural and urban populations.

CONCLUSION/INTERPRETATION

The incidence of Type I diabetes is rising in children living in Switzerland but only the youngest age group of under 5 years of age is affected showing a large annual average increase of 23.8%.

Clinical, genetic, and functional characterization of four patients carrying partial loss-of-function mutations in the steroidogenic acute regulatory protein (StAR)

CONTEXT

Nonclassic congenital lipoid adrenal hyperplasia (lipoid CAH) is a recently recognized disorder caused by mutations in the steroidogenic acute regulatory protein (StAR) that retain partial function. Affected individuals can present with a phenotype of late onset adrenal insufficiency with only mild or minimally disordered sexual development.

OBJECTIVES

The aim was to delineate the clinical spectrum of StAR mutations and correlate phenotype with StAR activity.

PATIENTS

Four patients had nonclassic/atypical lipoid CAH. Adrenal insufficiency was manifested at birth in two patients and at 11 months and 4 yr in the other two. Three were 46,XY with underdeveloped genitalia.

METHODS

The StAR gene was sequenced, mutations were recreated in expression vectors, and StAR activity was measured as pregnenolone production in COS-1 cells cotransfected with the cholesterol side-chain cleavage system. StAR mutants were expressed as N-62 StAR in bacteria, and purified proteins were tested for activity with isolated steroidogenic mitochondria and for cholesterol-binding capacity.

RESULTS

DNA sequencing identified mutations on all alleles. Missense mutations were R188C, G221D, L260P, and F267S; we also tested R192C described by others. The respective activities of R188C, R192C, G221D, L260P, and F267S were 8.0, 39.4, 2.4, 3.1, and 6.1% of wild-type in transfected cells, and 12.8, 54.8, 6.3, 1.8, and 9.5% with isolated mitochondria. Cholesterol binding capacities of R188C, R192C, G221D, L260P, and F267S were 6.7, 55.3, 10.2, 4.6, and 20.9%. These data are correlated to the three-dimensional structure of StAR.

CONCLUSIONS

There is a broad clinical spectrum of StAR mutations; StAR activities in vitro correlate well with clinical phenotypes.

Children with congenital hypothyroidism: long-term intellectual outcome after early high-dose treatment

We aim to determine long-term intellectual outcome of adolescents with early high-dose treated congenital hypothyroidism (CH). Sixty-three prospectively followed children with CH were assessed at age of 14 y with the Wechsler Intelligence Scale for Children-Revised and compared with 175 healthy controls. Median age at onset of treatment was 9 d (range 5-18 d) and median starting dose of levothyroxine (L-T4) was 14.7 microg/kg/d (range 9.9-23.6 microg/kg/d). Full-scale intelligence quotient (IQ) was significantly lower than in controls after adjustment for socioeconomic status (SES) and gender (101.7 versus 111.4; p < 0.0001). Children with athyreosis had a lower performance IQ than those with dysgenesis (adjusted difference 7.6 IQ scores, p < 0.05). Lower initial thyroxine (T4) levels correlated with poorer IQ (r = 0.27, p = 0.04). Lower SES was associated with poorer IQ, in particular in children with CH (interaction, p = 0.03). Treatment during childhood was not related to IQ at age 14 y. Adolescents with CH manifest IQ deficits when compared with their peers despite early high-dose treatment and optimal substitution therapy throughout childhood. Those adolescents with athyreosis and lower SES are at particular risk for adverse outcome. Therefore, early detection of intellectual deficits is mandatory in children with CH.

Loss of kinase activity in a patient with Wolcott-Rallison syndrome caused by a novel mutation in the EIF2AK3 gene

Wolcott-Rallison syndrome (WRS) is an autosomal recessive disorder characterized by neonatal or early infancy type 1 diabetes, epiphyseal dysplasia, and growth retardation. Mutations in the EIF2AK3 gene, encoding the eukaryotic initiation factor 2alpha-kinase 3 (EIF2AK3), have been found in WRS patients. Here we describe a girl who came to our attention at 2 months of age with severe hypertonic dehydration and diabetic ketoacidosis. A diagnosis of type 1 diabetes was made and insulin treatment initiated. Growth retardation and microcephaly were also present. Anti-islet cell autoantibodies were negative, and mitochondrial diabetes was excluded. Imaging revealed a hypoplastic pancreas and typical signs of spondylo-epiphyseal dysplasia. The diagnosis of WRS was therefore made at age 5 years. Sequencing analysis of her EIF2AK3 gene revealed the presence of a homozygous T to C exchange in exon 13 leading to the missense serine 877 proline mutation. The mutated kinase, although it partly retains the ability of autophosphorylation, is unable to phosphorylate its natural substrate, eukaryotic initiation factor 2alpha (eIF2alpha). This is the first case in which the pathophysiological role of EIF2AK3 deficiency in WRS is confirmed at the molecular level. Our data demonstrate that EIF2AK3 kinase activity is essential for pancreas islet function and bone development in humans, and we suggest EIF2AK3 as a possible target for therapeutic intervention in diabetes.

P450c17 deficiency: clinical and molecular characterization of six patients

CONTEXT

The characteristics of P450c17 deficiency include 46,XY disorder of sex development, hypertension, hypokalemia, and lack of pubertal development.

OBJECTIVE

To better understand this rare enzymatic deficiency, we analyzed the CYP17A1 gene in six affected patients.

DESIGN AND PATIENTS

We examined six patients, five 46,XY, and one 46,XX (age 9-29 yr) with complete lack of masculinization (female infantile external genitalia, no uterus) and delayed puberty, respectively, and different degrees of hypertension.

MAIN OUTCOME MEASUREMENTS

Genotype-phenotype correlation was measured.

RESULTS

Four homozygote mutations were identified by direct sequencing of the CYP17A1 gene corresponding to an alanin 302-proline (A302P) exchange; the loss of lysine 327 (K327del); the deletion of glutamate 331 (E331del); and the replacement of arginine 416 with a histidine (R416H). Both P450c17 activities were abolished in all the mutant proteins, except one, when expressed in COS1 cells. The E331del-mutated P450c17 retained 17alpha-hydroxylase activity. The mutant proteins were normally expressed, suggesting that the loss of enzymatic activity is not due to defects of synthesis, stability, or localization of P450c17 proteins.

CONCLUSION

These studies confirm lack of masculinization in 46,XY individuals as the pathognomic sign of the complete P450c17 deficiency. In XX individuals P450c17 deficiency should be considered in cases of delayed puberty. Age of onset and the severity of hypertension do not seem to be constant. Careful examination of long-term follow-ups in two of our patients suggested to us that estrogen treatment in P450c17-deficient patients might worsen the enzymatic defect, leading to aggravation of the hypertension.

Association of childhood type 1 diabetes mellitus with a variant of PAX4: possible link to beta cell regenerative capacity

AIMS/HYPOTHESIS

Loss of pancreatic beta cells is the crucial event in the development of type 1 diabetes. It is the result of an imbalance between autoimmune destruction and insufficient regeneration of islet cells. To study the role of islet cell regeneration in the pathogenesis of type 1 diabetes, we focused on PAX4, a paired homeodomain transcriptional repressor that is involved in islet cell growth.

METHODS

The study included 379 diabetic children and 1,070 controls from two distinct populations, and a cohort of children who had not developed type 1 diabetes, despite the presence of islet cell antibodies. Genomic DNA analysis of PAX4 was carried out via direct sequencing of PCR-amplified fragments and allelic discrimination. We compared the transrepression potential of the PAX4 variants in betaTC3 cells and analysed their influence on beta cell growth.

RESULTS

The type 1 diabetic subjects are different from the normal individuals in terms of the genotype distribution of the A1168C single nucleotide polymorphism in PAX4. The C/C genotype is frequent among type 1 diabetic children (73%) and rare among the control population (32%). Conversely, the A/C genotype is prevalent among control subjects (62%) and antibody-positive children without type 1 diabetes (73.6%), but uncommon among subjects with type 1 diabetes (17.5%). The combination of PAX4A and PAX4C is functionally more active than PAX4C alone (the "diabetic" variant). Beta cells expressing PAX4A and PAX4C efficiently proliferate when stimulated with glucose, whereas cells expressing the PAX4C variant alone do not.

CONCLUSIONS/INTERPRETATION

We have identified a link between beta cell regenerative capacity and susceptibility to type 1 diabetes. This finding could explain the fact that not all of the individuals who develop autoimmunity against beta cells actually contract the disease. The C/C genotype of the A1168C polymorphism in PAX4 can be viewed as a predisposition marker that can help to detect individuals prone to develop type 1 diabetes.

When genetic load does not correlate with phenotypic spectrum: lessons from the GnRH receptor (GNRHR)

CONTEXT

A broad spectrum of GnRH-deficient phenotypes has been identified in individuals with both mono- and biallelic GNRHR mutations.

OBJECTIVE

The objective of the study was to determine the correlation between the severity of the reproductive phenotype(s) and the number and functional severity of rare sequence variants in GNRHR.

SUBJECTS

Eight hundred sixty-three probands with different forms of GnRH deficiency, 46 family members and 422 controls were screened for GNRHR mutations. The 70 subjects (32 patients and 38 family members) harboring mutations were divided into four groups (G1-G4) based on the functional severity of the mutations (complete or partial loss of function) and the number of affected alleles (monoallelic or biallelic) with mutations, and these classes were mapped on their clinical phenotypes.

RESULTS

The prevalence of heterozygous rare sequence variants in GNRHR was significantly higher in probands vs. controls (P < 0.01). Among the G1-G3 groups (homozygous subjects with successively decreasing severity and number of mutations), the hypogonadotropic phenotype related to their genetic load. In contrast, subjects in G4, with only monoallelic mutations, demonstrated a greater diversity of clinical phenotypes.

CONCLUSIONS

In patients with GnRH deficiency and biallelic mutations in GNRHR, genetic burden defined by severity and dose is associated with clinical phenotype. In contrast, for patients with monoallelic GNRHR mutations this correlation does not hold. Taken together, these data indicate that as-yet-unidentified genetic and/or environmental factors may combine with singly mutated GNRHR alleles to produce reproductive phenotypes.

Early-Onset Complete Ovarian Failure and Lack of Puberty in a Woman With Mutated Estrogen Receptor β (ESR2)

CONTEXT

Estrogen resistance due to mutations in the estrogen receptor α gene (ESR1) has been described in men and women and is characterized by osteoporosis, delayed bone age and continuous growth in adulthood, and delayed puberty and multiple ovarian cysts in women. Although mutations in the estrogen receptor β gene ESR2 were found in 46, XY patients with differences of sex development, no genetic variants of ESR2 were linked to gonadal defects in women.

SETTINGS AND PATIENT

Here we describe a 16-year-old female patient who came to our tertiary care hospital with complete lack of estrogen action, as demonstrated by absent breast development, primary amenorrhea, and osteoporosis, resembling patients with ESR1 mutation. However, her gonads were clearly abnormal (streak), a finding not observed in ESR1-deficient patients.

DESIGN

To gain insights into the molecular consequences of the ESR2 defect, whole exome sequencing and extensive functional transactivation studies in ovarian, bone, and breast cells were conducted, with or without the natural activator of estrogen receptors, 17β-estradiol.

RESULTS

We identified a loss-of-function heterozygous mutation of a highly conserved residue in ESR2 that disrupts estradiol-dependent signaling and has a dominant negative effect, most likely due to failure to interact with its coactivator, nuclear coactivator 1.

CONCLUSIONS

This is a report of a loss-of-function mutation in the estrogen receptor β in a young woman with complete ovarian failure, suggesting that ESR2 is necessary for human ovarian determination and/or maintenance and that ESR1 is not sufficient to sustain ovarian function in humans.

Aromatase deficiency owing to a functional variant in the placenta promoter and a novel missense mutation in the CYP19A1 gene

CONTEXT

Aromatase deficiency in women is a rare 46, XX disorder of sex differentiation characterized by a defect in catalysing oestrogens from androgens.

OBJECTIVE

To better understand this rare disorder, we searched for mutations in the CYP19A1 gene of an affected girl and analysed their functional consequences.

DESIGN AND PATIENT

We examined a girl presenting with clitoral hypertrophy at birth and mild maternal virilization (acne) during pregnancy.

MAIN OUTCOME MEASUREMENT

A genotype-phenotype correlation was found.

RESULTS

By direct sequencing of the CYP19A1 gene, we identified a heterozygous A>G mutation (c. A1374G) mutation in exon IX, leading to the missense p.N411S in the P450Aro protein and a heterozygous placenta promoter variant -41 base pairs upstream of exon I.1. Aromatase enzyme activity was completely lost when the mutant p.N411S protein was expressed in COS-1 cells. The placenta promoter variant had a significantly reduced (-50%) transactivation ability compared to wild-type.

CONCLUSION

Our data describe a novel loss-of-function missense mutation in CYP19A1 combined with the first-described variant of the placenta promoter with a significant reduction in function, likely to be the molecular basis of this rare 46, XX disorder of sex development. This seems to represent a unique case of aromatase deficiency occurring in utero only.

DCC/NTN1 complex mutations in patients with congenital hypogonadotropic hypogonadism impair GnRH neuron development

Congenital hypogonadotropic hypogonadism (CHH) is a rare genetic disease characterized by absent puberty and infertility due to GnRH deficiency, and is often associated with anosmia [Kallmann syndrome (KS)]. The genetic etiology of CHH is heterogeneous, and more than 30 genes have been implicated in approximately 50% of patients with CHH. We hypothesized that genes encoding axon-guidance proteins containing fibronectin type-III (FN3) domains (similar to ANOS1, the first gene associated with KS), are mutated in CHH. We performed whole-exome sequencing in a cohort of 133 CHH probands to test this hypothesis, and identified rare sequence variants (RSVs) in genes encoding for the FN3-domain encoding protein deleted in colorectal cancer (DCC) and its ligand Netrin-1 (NTN1). In vitro studies of these RSVs revealed altered intracellular signaling associated with defects in cell morphology, and confirmed five heterozygous DCC mutations in 6 probands-5 of which presented as KS. Two KS probands carry heterozygous mutations in both DCC and NTN1 consistent with oligogenic inheritance. Further, we show that Netrin-1 promotes migration in immortalized GnRH neurons (GN11 cells). This study implicates DCC and NTN1 mutations in the pathophysiology of CHH consistent with the role of these two genes in the ontogeny of GnRH neurons in mice.

NOS1 mutations cause hypogonadotropic hypogonadism with sensory and cognitive deficits that can be reversed in infantile mice

The nitric oxide (NO) signaling pathway in hypothalamic neurons plays a key role in the regulation of the secretion of gonadotropin-releasing hormone (GnRH), which is crucial for reproduction. We hypothesized that a disruption of neuronal NO synthase (NOS1) activity underlies some forms of hypogonadotropic hypogonadism. Whole-exome sequencing was performed on a cohort of 341 probands with congenital hypogonadotropic hypogonadism to identify ultrarare variants in NOS1. The activity of the identified NOS1 mutant proteins was assessed by their ability to promote nitrite and cGMP production in vitro. In addition, physiological and pharmacological characterization was carried out in a Nos1-deficient mouse model. We identified five heterozygous NOS1 loss-of-function mutations in six probands with congenital hypogonadotropic hypogonadism (2%), who displayed additional phenotypes including anosmia, hearing loss, and intellectual disability. NOS1 was found to be transiently expressed by GnRH neurons in the nose of both humans and mice, and Nos1 deficiency in mice resulted in dose-dependent defects in sexual maturation as well as in olfaction, hearing, and cognition. The pharmacological inhibition of NO production in postnatal mice revealed a critical time window during which Nos1 activity shaped minipuberty and sexual maturation. Inhaled NO treatment at minipuberty rescued both reproductive and behavioral phenotypes in Nos1-deficient mice. In summary, lack of NOS1 activity led to GnRH deficiency associated with sensory and intellectual comorbidities in humans and mice. NO treatment during minipuberty reversed deficits in sexual maturation, olfaction, and cognition in Nos1 mutant mice, suggesting a potential therapy for humans with NO deficiency.

A novel mutation in the anti-müllerian hormone gene as cause of persistent müllerian duct syndrome

Persistent müllerian duct syndrome is a relatively rare inherited defect of sexual differentiation characterised by failure of regression of the müllerian ducts in males. In affected individuals, uterus and tubes are present because of defects of synthesis or action of anti-müllerian hormone (AMH), normally produced by the Sertoli cells of the testis. Patients are normally virilised, although mono- or bilateral cryptorchidism may be present. We observed two brothers (chromosomes 46 XY), aged 11 years and 2 months and 8 years and 3 months respectively, with bilateral cryptorchidism. The diagnosis of persistent müllerian duct syndrome was made on the basis of laparoscopic evidence of uterus and tubes, undetectable plasma levels of AMH and a 23 base pair duplicative insertion in exon 5 of the AMH gene, causing the introduction of a premature stop codon, homozygous in the two brothers. The surgical correction of the genital abnormalities was successfully carried out by laparoscopic orchidopexy according to Fowler-Stephens.

CONCLUSION

Persistent müllerian duct syndrome should be taken into consideration in all cases of bilateral cryptorchidism. Laparoscopy is the elective procedure for diagnosis of this disease and laparoscopic surgery for orchidopexy of intra-abdominal testes. Mutation analysis of the anti-müllerian hormone gene in these patients helps to understand the structure-function relationship of the anti-müllerian hormone protein, although it is not clear at present whether anti-müllerian hormone is necessary to maintain normal testicular function.

Clinical, genetic and functional characteristics of three novel CYP17A1 mutations causing combined 17alpha-hydroxylase/17,20-lyase deficiency

BACKGROUND

P450c17 has two distinct activities: 17alpha-hydroxylase activity and 17,20-lyase activity. Combined 17alpha-hydroxylase/17,20-lyase deficiency leads to a severe defect in the production of cortisol and sex steroids. In affected males this results in impaired masculinization with ambiguous or female external genitalia. Female patients have normal genitalia but show a lack of pubertal development in adolescence. An increased production of mineralocorticoids often leads to hypertension and hypokalemia in both sexes.

METHODS

To better understand the mechanisms of P450c17 deficiency, we studied 2 patients (both 46,XY) with combined 17alpha-hydroxylase/17,20-lyase deficiency of different severity: one with complete lack of masculinization and one with ambiguous genitalia.

RESULTS

Four mutations were identified by sequencing of the CYP17A1 gene: I332T and A355T in the less severely affected patient; G111S and R440H in the patient with complete lack of masculinization. The three novel mutations were expressed in COS1 cells and all mutant proteins except I332T showed a complete loss of both enzymatic activities. I332T retained some residual 17alpha-hydroxylase as well as 17,20-lyase activity.

CONCLUSION

We identified 2 patients with the phenotypical spectrum of P450c17 deficiency. Three novel mutations in the CYP17A1 gene were identified and their functional characterization provided a good phenotype-genotype correlation. The location of the mutated residues in the three-dimensional model of P450c17 gave some additional insights into its structure-function relationship.

Estrogens: Two nuclear receptors, multiple possibilities

Much is known about estrogen action in experimental animal models and in human physiology. This article reviews the mechanisms of estrogen activity in animals and humans and the role of its two receptors α and β in terms of structure and mechanisms of action in various tissues in health and in relationship with human pathologies (e.g., osteoporosis). Recently, the spectrum of clinical pictures of estrogen resistance caused by estrogen receptors gene variants has been widened by our description of a woman with β-receptor defect, which could be added to the already known descriptions of α-receptor defect in women and men and β-receptor defect in men. The essential role of the β-receptor in the development of the gonad stands out. We summarize the clinical pictures due to estrogen resistance in men and women and focus on long-term follow-up of two women, one with α- and the other with β-receptor resistance. Some open questions remain on the complex interactions between the two receptors on bone metabolism and hypothalamus-pituitary-gonadal axis, which need further deepening and research.

Epidermolysis bullosa junctionalis progressiva in three siblings

Three siblings of Swiss origin with epidermolysis bullosa junctionalis progressiva are described. The following clinical features were present from school age: dystrophy of the nails, non-scarring blistering of the skin, mild skin atrophy, hypodontia and dental caries. Light microscopy showed subepidermal blistering. Direct immunofluorescence was negative. On indirect immunofluorescence staining of a fresh spontaneous blister, bullous pemphigoid antigen and laminin were localized to the blister roof, and collagen IV and collagen VII to the blister base, indicating junctional splitting. Electron microscopy revealed a normal dermo-epidermal junction zone, including normal hemidesmosomes. There were no deposits of electron-dense amorphous material.

Genetic testing facilitates prepubertal diagnosis of congenital hypogonadotropic hypogonadism

Neonatal micropenis and cryptorchidism raise the suspicion of congenital hypogonadotropic hypogonadism (CHH), a rare genetic disorder caused by gonadotropin-releasing hormone deficiency. Low plasma testosterone levels and low gonadotropins during minipuberty provide a clinical diagnostic clue, yet these tests are seldomly performed in general practice. We report a male neonate with no family history of reproductive disorders who was born with micropenis and cryptorchidism. Hormonal testing at age 2.5 months showed low testosterone (0.3 nmol/L) and undetectable gonadotropins (luteinizing hormone and follicle-stimulating hormone both <0.5 U/L), suggestive of CHH. Genetic testing identified a de novo, heterozygous mutation in fibroblast growth factor receptor 1 (FGFR1 p.L630P). L630 resides on the ATP binding cleft of the FGFR1 tyrosine kinase domain, and L630P is predicted to cause a complete loss of receptor function. Cell-based assays confirmed that L630P abolishes FGF8 signaling activity. Identification of a loss-of-function de novo FGFR1 mutation in this patient confirms the diagnosis of CHH, allowing for a timely hormonal treatment to induce pubertal development. Therefore, genetic testing can complement clinical and hormonal assessment for a timely diagnosis of CHH in childhood.

Exome sequencing identifies a de novo FOXA2 variant in a patient with syndromic diabetes

OBJECTIVE

When diabetes is associated with congenital malformations, without autoimmune antibodies, a genetic cause is suspected. Here, we aimed to identify a defective gene that led to diabetes.

RESEARCH DESIGN AND METHODS

We performed an exome analysis of an index case and his healthy parents.

RESULTS

The child presented with childhood-onset diabetes, congenital hypopituitarism, cardiac malformation, and anal atresia. A DNA analysis revealed a heterozygous de novo pathogenic variant in the developmental transcription factor, forkhead box A2 (FOXA2). The mutation resided in the DNA-binding domain, which is highly conserved among species. Tridimensional molecular dynamics simulation modeling predicted an altered interaction between the mutated protein and DNA.

CONCLUSIONS

A defect in the FOXA2 DNA-binding domain was associated with childhood-onset diabetes and multiple congenital anomalies, which reflected the pleiotropic nature of the gene. This report extends the recently described phenotype of neonatal hypoglycemia to later-onset diabetes. We suggest to include FOXA2 analysis for neonatal hypoglycemia and to implement a long-term follow-up, particularly for the risk of diabetes.

Incidence of enteropathy-associated T-cell lymphoma in celiac disease: implications for children and adolescents with type 1 diabetes

The long-term consequences of screening for celiac disease in diabetic children are not known. Routine screening is not practiced in our pediatric diabetic population. This study of the incidence of the most severe and specific long-term complication of untreated celiac disease, i.e., enteropathy-associated T-cell lymphoma (EATCL) and its association with diabetes, is done in order to justify our strategy not to practice routine screening. In the first phase of this study, a questionnaire was sent to all Swiss pathologists. The second phase consisted of a search in the cancer registry of the canton of Zurich. The incidence of EATCL in the general population of a Swiss region and the theoretical risk for a diabetic patient to develop this type of lymphoma were calculated. Ten cases of EATCL were found. Five had a long history of malabsorption, three of them since childhood. The mean age of the patients was 61.9 yr. None suffered from diabetes mellitus. The incidence of EATCL was 0.07/100,000 inhabitants/year. The expected risk for EATCL in patients with type 1 diabetes is 12.4/100,000 diabetic patients over a period of 60 yr. The data suggest that the risk for EATCL is small in diabetic patients. Therefore, we restrict the investigation for celiac disease to patients with typical and atypical symptoms, but do not perform routine screening.

Improved glycemic control and lower frequency of severe hypoglycemia with insulin detemir; long-term experience in 105 children and adolescents with type 1 diabetes

OBJECTIVE

To assess the effect of the insulin analog detemir on glycemic control and severe hypoglycemia in children and adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

A retrospective chart analysis was performed in 105 patients with type 1 diabetes after switching to insulin detemir between 2004 and 2007. In children below 12 yr of age (n = 53), evening neutral protomin hagedorn (NPH) insulin was replaced by insulin detemir if therapeutic goals were not reached and blood glucose levels were unpredictable or hardly controllable. In adolescents above 12 yr of age (n = 52), insulin detemir was started when changing to intensified insulin therapy.

RESULTS

In children below 12 yr of age, hemoglobin A1c (HbA1c) at start was 8.3 +/- 0.8% and after 12 months of treatment with insulin detemir significantly lowered (7.6 +/- 0.6%, p < 0.001). In the age-group above 12 yr of age at the start of the study, the improvement of HbA1c after 12 months of treatment was less pronounced (8.0 +/- 1.2 vs. 7.6 +/- 1.0%) but still significant (p < 0.01). The risk for severe hypoglycemia was significantly decreased compared with patients attending the outpatient clinic between 1995 and 2003 (4.8/100 patient years vs. 7.6/100 patient years, p = 0.003). From the beginning to the end of the follow-up period, body mass index dropped significantly in children below 12 yr of age but no effect was observed in adolescents.

CONCLUSIONS

Use of insulin detemir allows a safe nocturnal glycemic control in children and adolescents with type 1 diabetes and is associated with significantly improved HbA1c levels and fewer severe hypoglycemic events. This makes insulin detemir a most valuable new tool for the treatment of children and adolescents with type 1 diabetes.

Importance of genetic diagnosis of DAX-1 deficiency: example from a large, multigenerational family

BACKGROUND

Inactivating mutations of DAX-1 give rise to the X-linked form of adrenal hypoplasia congenita (AHC). Affected fetuses are at risk of early postnatal Addisonian crisis, but the variable phenotypic expression of DAX-1 insufficiency renders this diagnosis challenging.

METHODS

We describe the familial transmission of AHC over several generations. The proband was diagnosed with adrenal insufficiency at age 3.5 years: molecular analysis revealed a novel, 373-bp deletion including the second exon of DAX-1. Given the familial history of several unexplained deaths in male infants related to the proband via his maternal great-grandmother, we hypothesized that all these boys had been affected with AHC. Another female member of the family being pregnant with a male fetus at the time, we performed DAX-1 analysis on the mother and the newborn. The mother was heterozygous for the deletion, and the newborn hemizygous: he presented an adrenal crisis at 10 days of life, and is now doing well on hormone replacement therapy.

CONCLUSION

The unfortunate deaths of male infants at each generation of this family underlie the importance of early and precise diagnosis of this rare condition, stressing the value of genetic diagnosis in six potential female carriers of this family entering their reproductive years.

A novel GATA6 variant in a boy with neonatal diabetes and diaphragmatic hernia: a familial case with a review of the literature

GATA6 gene variants come along with possible features such as pancreas agenesis/hypoplasia, neonatal diabetes and congenital heart defect. Congenital hypothyroidism, and hepatobiliary and gut abnormalities are also detectable. Children with congenital heart defects and neonatal diabetes were already described in 1970. GATA6 variants can be due to de novo variants or due to inherited variants. To date, 11 cases due to an inherited variant have been described. Herein we present a novel heterozygous GATA6 variant (c.1291C > T p.[Gln431*]) in a boy with transient neonatal diabetes, diaphragmatic hernia, congenital heart defect and early-onset scoliosis. The same variant was also present in the mother. At the age of 3 years, a random evaluation revealed a hemoglobin A1c (HbA1c) level of 7.8% (62 mmol/mol) without any diabetes-related symptoms. He was started on insulin therapy and HbA1c normalized. A short review of the literature of hereditary cases of the GATA6 variant revealed the variable phenotypic spectrum and showed that patients with a mild phenotype are likely to have children with a more severe phenotype.

Double variants in TSHR and DUOX2 in a patient with hypothyroidism: case report

Thyroid dyshormonogenesis (TDH) is characterized by the defective synthesis of thyroid hormones. We present a patient with congenital hypothyroidism (CH) who presented in newborn screening with elevated serum thyroid-stimulating hormone (TSH), decreased free thyroxine (fT4) and increased thyroglobulin (Tg) concentrations. Ultrasound scan revealed a properly structured thyroid gland. Treatment with L-thyroxine was initiated. At the age of 2 years, thyroxine replacement was stopped. The patient remained untreated until 6 years of age when TSH levels progressively increased and L-thyroxine treatment was restarted at a dose of 12.5 μg/day. Genetic analysis revealed a double heterozygosity for likely pathogenic variants of dual oxidase 2 (DUOX2) and thyroid stimulating hormone receptor (TSHR). Both genes were earlier shown to be associated with CH. In a literature review, our patient was compared to previously published patients with similar clinical characteristics, and a good genotype-phenotype correlation was identified.