Pascal Philibert

Identification and functional analysis of a new WNT4 gene mutation among 28 adolescent girls with primary amenorrhea and Müllerian duct abnormalities: A french collaborative study

CONTEXT Müllerian duct development depends on gene and hormone interactions. Female Wnt4-knockout mice lack müllerian ducts and are virilized due to the inappropriate expression of the enzymes required for androgen production (normally repressed in female ovary). The WNT4 mutation was recently reported to be associated with failure of müllerian duct formation and virilization in two 46, XX women. OBJECTIVES This collaborative work was designed to determine whether the WNT4 mutation could be identified in a group of adolescent girls with Mayer-Rokitansky-Küster-Hauser syndrome. RESULTS We analyzed 28 DNA samples from adolescent girls with primary amenorrhea and failure of müllerian duct formation by direct sequencing and identified a new L12P mutation within exon 1 of the WNT4 gene. The substitution of leucine by proline is crucial for the conformation of the expressed protein. This amino acid substitution is unlikely to be a polymorphism because it was not found in 100 DNAs from control subjects. Functional analysis revealed that the mutation induces significantly increased expression of the enzymes involved in androgen biosynthesis (3beta-hydroxysteroid dehydrogenase and 17alpha-hydroxylase). It is interesting to note that the adolescent carrying the mutation was referred to our clinic for primary amenorrhea and hyperandrogenism (severe acne and plasma testosterone: 1.8 vs. 1.2 nmol/liter in controls). She also presented with uterine hypoplasia and follicle depletion. CONCLUSIONS We suggest that in adolescent girls with primary amenorrhea, müllerian duct abnormalities, and hyperandrogenism, a WNT4 mutation should be sought. Moreover, our data confirm that WNT4 is involved in the regulation of müllerian duct development and ovarian androgen biosynthesis. WNT4 may also contribute to human follicle development and/or maintenance.

Is hypospadias a genetic, endocrine or environmental disease, or still an unexplained malformation?

Hypospadias is one of the most frequent genital malformations in the male newborn and results from an abnormal penile and urethral development. This process requires a correct genetic programme, time- and space-adapted cellular differentiation, complex tissue interactions, and hormonal mediation through enzymatic activities and hormonal transduction signals. Any disturbance in these regulations may induce a defect in the virilization of the external genitalia and hypospadias. This malformation thus appears to be at the crossroads of various mechanisms implicating genetic and environmental factors. The genes of penile development (HOX, FGF, Shh) and testicular determination (WT1, SRY) and those regulating the synthesis [luteinizing hormone (LH) receptor] and action of androgen (5alpha reductase, androgen receptor) can cause hypospadias if altered. Several chromosomal abnormalities and malformative syndromes include hypospadias, from anterior to penoscrotal forms. More recently, CXorf6 and ATF3 have been reported to be involved. Besides these genomic and hormonal factors, multiple substances found in the environment can also potentially interfere with male genital development because of their similarity to hormones. The proportion of hypospadias cases for which an aetiology is detected varies with the authors but it nevertheless remains low, especially for less severe cases. An interaction between genetic background and environment is likely.

Phenotypical, Biological, and Molecular Heterogeneity of 5α-Reductase Deficiency: An Extensive International Experience of 55 Patients

CONTEXT In 46,XY disorders of sex development, 5α-reductase deficiency is rare and is not usually the first-intention diagnosis in newborn ambiguous genitalia, contrary to partial androgen insensitivity syndrome. Yet the cause of ambiguous genitalia may guide sex assignment, and rapid, precise diagnosis of 5α-reductase deficiency is essential. OBJECTIVE The aim of the study was to describe relevant data for clinical diagnosis, biological investigation, and molecular determination from 55 patients with srd5A2 mutations identified in our laboratory over 20 yr to improve early diagnosis. SETTING The study was performed at Montpellier University Hospital. PATIENTS We studied a cohort of 55 patients with srd5A2 gene mutations. MAIN OUTCOME MEASURE(S) Genetic analysis of srd5A2 was conducted. RESULTS Clitoromegaly (49.1%) and microphallus with various degrees of hypospadias (32.7%) were frequent phenotypes. Female external genitalia (7.3%) and isolated micropenis (3.6%) were rare. Seventy-two percent of patients were initially assigned to female gender; five of them (12.5%) switched to male sex in peripuberty. Over 72% of patients were considered for 5α-reductase deficiency diagnosis when the testosterone/dihydrotestosterone cutoff was 10. In 55 patients (with 20 having a history of consanguinity), we identified 33 different mutations. Five have never been reported: p.G32S, p.Y91H, p.G104E, p.F223S, and c.461delT. Homozygous mutations were present in 69.1% of cases, compound heterozygous mutations in 25.5%, and compound heterozygous mutations alone with the V89L polymorphism in 5.4%. Exons 1 and 4 were most affected, with 35.8 and 21.7% mutant alleles per exon, respectively. CONCLUSIONS In the largest cohort to date, we demonstrate a wide spectrum of phenotypes and biological profiles in patients with 5α-reductase deficiency, whatever their geographical or ethnic origins.

Mayer-Rokitansky-Kuster-Hauser syndrome : Recent clinical and genetic findings

Mayer–Rokitansky–Kuster–Hauser (MRKH) syndrome is characterized by Müllerian duct aplasia in an XX individual with female phenotype presenting primary amenorrhea at adolescence. Multiple abnormalities may be associated with the MRKH syndrome. Genetic investigations focused on the genes of anti-Müllerian hormone and its receptor, as well as on Wt1, Pax2, Cftr and Hox genes, have been unproductive. Only the Wnt4 gene has been clearly implicated in MRKH syndrome and found to be associated with clinical and/or biological signs of hyperandrogenism in three different works. Beside the multiple malformations that may be associated with MRKH syndrome, such as renal, skeletal, cardiac and auditory defects, MRKH and hyperandrogenism represent a new clinical and genetic disorder.

A focused antibody library for selecting scFvs expressed at high levels in the cytoplasm

BackgroundIntrabodies are defined as antibody molecules which are ectopically expressed inside the cell. Such intrabodies can be used to visualize or inhibit the targeted antigen in living cells. However, most antibody fragments cannot be used as intrabodies because they do not fold under the reducing conditions of the cell cytosol and nucleus.ResultsWe describe the construction and validation of a large synthetic human single chain antibody fragment library based on a unique framework and optimized for cytoplasmic expression. Focusing the library by mimicking the natural diversity of CDR3 loops ensured that the scFvs were fully human and functional. We show that the library is highly diverse and functional since it has been possible to isolate by phage-display several strong binders against the five proteins tested in this study, the Syk and Aurora-A protein kinases, the αβ tubulin dimer, the papillomavirus E6 protein and the core histones. Some of the selected scFvs are expressed at an exceptional high level in the bacterial cytoplasm, allowing the purification of 1 mg of active scFv from only 20 ml of culture. Finally, we show that after three rounds of selection against core histones, more than half of the selected scFvs were active when expressed in vivo in human cells since they were essentially localized in the nucleus.ConclusionThis new library is a promising tool not only for an easy and large-scale selection of functional intrabodies but also for the isolation of highly expressed scFvs that could be used in numerous biotechnological and therapeutic applications.

Molecular analysis of WNT4 gene in four adolescent girls with mullerian duct abnormality and hyperandrogenism (atypical Mayer-Rokitansky-Küster-Hauser syndrome)

In a collaborative study, we investigated four 46,XX adolescent girls with Mayer-Rokitansky-Küster-Hauser syndrome and hyperandrogenism. Molecular analysis of the WNT4 gene permitted us to identify a new mutation (p.A233T). Functional studies revealed partial repression of steroidogenic enzymes (normal repression of HSD3B2) contrasting with the abnormal reexpression of CYP17A1 enzyme in the OVCAR3 cell line. This fourth new WNT4 mutation confirms that this signaling molecule is involved in mullerian development and androgen biosynthesis repression in the ovary. Interestingly, this mutant partially lacks the capability to repress ovarian steroidogenic enzymes, with abnormal expression of 17α- hydroxylase.

Steroidogenic factor-1 (SF-1) gene mutation as a frequent cause of primary amenorrhea in 46,XY female adolescents with low testosterone concentration

BackgroundPrimary amenorrhea due to 46,XY disorders of sex differentiation (DSD) is a frequent reason for consultation in endocrine and gynecology clinics. Among the genetic causes of low-testosterone primary amenorrhea due to 46,XY DSD, SRY gene is reported to be frequently involved, but other genes, such as SF1 and WT1, have never been studied for their prevalence.MethodsWe directly sequenced SRY, SF1 and WT1 genes in 15 adolescent girls with primary amenorrhea, low testosterone concentration, and XY karyotype, to determine the prevalence of mutations. We also analyzed the LH receptor gene in patients with high LH and normal FSH concentrations.ResultsAmong the 15 adolescents with primary amenorrhea and low testosterone concentration, we identified two new SRY mutations, five new SF1 mutations and one new LH receptor gene mutation. Our study confirms the 10-15% prevalence of SRY mutations and shows the high prevalence (33%) of SF1 abnormalities in primary amenorrhea due to 46,XY DSD with low plasma testosterone concentration.ConclusionsThe genetic analysis of low-testosterone primary amenorrhea is complex as several factors may be involved. This work underlines the need to systematically analyze the SF1 sequence in girls with primary amenorrhea due to 46,XY DSD and low testosterone, as well as in newborns with 46,XY DSD.

Functional evidence implicating FOXL2 in non-syndromic premature ovarian failure and in the regulation of the transcription factor OSR2

Background: FOXL2 encodes a forkhead transcription factor whose mutations are responsible for the blepharophimosis-ptosis-epicanthus inversus syndrome (BPES), involving craniofacial/palpebral abnormalities often associated with premature ovarian failure (POF). Results: We describe a FOXL2 variant (p.Gly187Asp) in a case of POF without BPES. The subcellular localisation of FOXL2-G187D was normal but its transactivation capacity tested on two reporter promoters, one of which should be relevant to the ovary, was significantly lower than that of normal FOXL2. However, FOXL2-G187D was able to activate strongly a reporter construct driven by the promoter of Osr2 (odd-skipped related 2 transcription factor), which we have suggested to be a crucial target of FOXL2 in the craniofacial region. This is compatible with the absence of BPES in our patient. Conclusions: Our data provide evidence in favour of the implication of FOXL2 variants in non-syndromic POF and confirm the regulatory interaction between FOXL2 and OSR2 whose perturbation might contribute to the palpebral abnormalities observed in BPES patients.

Peripubertal female athletes in high-impact sports show improved bone mass acquisition and bone geometry.

OBJECTIVE Intensive physical training may have a sport-dependent effect on bone mass acquisition. This cross-sectional study evaluated bone mass acquisition in girls practicing sports that put different mechanical loads on bone. MATERIALS/METHODS Eighty girls from 10.7 to 18.0 years old (mean 13.83 ± 1.97) were recruited: 20 artistic gymnasts (AG; high-impact activity), 20 rhythmic gymnasts (RG; medium-impact activity), 20 swimmers (SW, no-impact activity), and 20 age-matched controls (CON; leisure physical activity <3h/wk). Areal bone mineral density (aBMD) was determined using DEXA. Hip structural analysis applied at the femur evaluated cross-sectional area (CSA, cm(2)), section modulus (Z, cm(3)), and buckling ratio. Bone turnover markers and OPG/RANKL levels were analyzed. RESULTS AG had higher aBMD than SW and CON at all bone sites and higher values than RG in the lumbar spine and radius. RG had higher aBMD than SW and CON only in the femoral region. CSA and mean cortical thickness were significantly higher and the buckling ratio was significantly lower in both gymnast groups compared with SW and CON. In RG only, endocortical diameter and width were reduced, while Z was only increased in AG compared with SW and CON. Reduced bone remodeling was observed in RG compared with AG only when groups were subdivided according to menarcheal status. All groups showed similar OPG concentrations, while RANKL concentrations increased with age and were decreased in SW. CONCLUSION High-impact activity clearly had a favorable effect on aBMD and bone geometry during the growth period, although the bone health benefits seem to be more marked after menarche.

Is Hypospadias Associated with Prenatal Exposure to Endocrine Disruptors? A French Collaborative Controlled Study of a Cohort of 300 Consecutive Children Without Genetic Defect

BACKGROUND Numerous studies have focused on the association between endocrine-disrupting chemicals (EDCs) and hypospadias. Phenotype variability, the absence of representative comparison groups and concomitant genetic testing prevent any definitive conclusions. OBJECTIVE To identify the role of occupational and environmental exposures to EDCs in nongenetic isolated hypospadias. DESIGN, SETTING, AND PARTICIPANTS A total of 408 consecutive children with isolated hypospadias and 302 normal boys were prospectively included (2009-2014) in a multi-institutional study in the south of France, the area of the country with the highest prevalence of hypospadias surgery. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS In patients without AR, SRD5A2, and MAMLD1 mutations, parental occupational and professional exposures to EDCs were evaluated based on European questionnaire QLK4-1999-01422 and a validated job-exposure matrix for EDCs. Environmental exposure was estimated using the zip code, the type of surrounding hazards, and distance from these hazards. Multivariate analysis was performed. RESULTS Fetal exposure to EDCs around the window of genital differentiation was more frequent in the case of hypospadias (40.00% vs 17.55%, odds ratio 3.13, 95% confidence interval 2.11-4.65). The substances were paints/solvents/adhesives (16.0%), detergents (11.0%), pesticides (9.0%), cosmetics (5.6%), and industrial chemicals (4.0%). Jobs with exposure were more frequent in mothers of hypospadiac boys (19.73% vs 10.26%, p=0.0019), especially cleaners, hairdressers, beauticians, and laboratory workers. Paternal job exposure was more frequent in the cases of hypospadias (40.13% vs 27.48%, p=0.02). Industrial areas, incinerators, and waste areas were more frequent within a 3-km radius for mothers of hypospadiac boys (13.29% vs. 6.64%, p<0.00005). Association of occupational and environmental exposures increases this risk. CONCLUSIONS This multicenter prospective controlled study with a homogeneous cohort of hypospadiac boys without genetic defects strongly suggests that EDCs are a risk factor for hypospadias through occupational and environmental exposure during fetal life. The association of various types of exposures may increase this risk. PATIENT SUMMARY Our multi-institutional study showed that parental professional, occupational, and environmental exposures to chemical products increase the risk of hypospadias in children.