Daniela Söderlund

A novel mutation of the insulin-like 3 gene in patients with cryptorchidism

AbstractTwo independent studies demonstrated that transgenic mice with a targeted deletion of the insulin-like 3 (INSL3) gene presented bilateral cryptorchidism. Studies in humans have investigated the possibility that mutations in the INSL3 gene are the cause of cryptorchidism. In the present study, genomic DNA was obtained from 150 patients with idiopathic cryptorchidism. DNA was amplified and the polymerase chain reaction products of both exons were sequenced. A previously unidentified missense mutation was found in only one of the patients studied. In exon 2, a heterozygous C/G substitution at nucleotide 2560, which turned asparagine into lysine at codon 86, was documented. The familial study revealed that the mother was a heterozygous carrier of the mutation and the father was a homozygote wild type. We also found three polymorphic changes, previously reported in exon 1. The Asn-into-Lys change is likely deleterious because it leads to a nonconservative amino acid substitution, changing a highly conserved residue. This mutation, located in the A-chain of the INSL3 protein, is the first mutation reported in this region. This finding provides new evidence that INSL3 is involved in testicular descent in humans; however, mutations of this gene are not a frequent cause of cryptorchidism.

Molecular analysis in true hermaphroditism: demonstration of low-level hidden mosaicism for Y-derived sequences in 46,XX cases

Abstract. True hermaphroditism (TH) is an unusual form of sex reversal, characterized by the development of testicular and ovarian tissue in the same subject. Approximately 60% of the patients have a 46,XX karyotype, 33% are mosaics with a second cell line containing a Y chromosome, while the remaining 7% are 46,XY. Molecular analyses have demonstrated that SRY is present in only 10% of TH with a 46,XX karyotype; therefore, in the remaining 90%, mutations at unknown X-linked or autosomal sex determining loci have been proposed as factors responsible for testicular development. True hermaphroditism presents considerable genetic heterogeneity with several molecular anomalies leading to the dual gonadal development as SRY point mutations or SRY hidden gonadal mosaicism. In order to identify genetic defects associated with subjects with the disease, we performed molecular analyses of the SRY gene in DNA from blood leukocytes and gonadal tissue in 12 true hermaphrodites with different karyotypes. Our results using PCR and FISH analyses reveal the presence of hidden mosaicism for SRY or other Y sequences in some patients with XX true hermaphroditism and confirms that mosaicism for SRY limited to the gonads is an alternative mechanism for testicular development in 46,XX true hermaphrodites.

Genetic Analysis in Patients With Kallmann Syndrome: Coexistence of Mutations in Prokineticin Receptor 2 and KAL1

Kallmann syndrome (KS) is characterized by the association of hypogonadotropic hypogonadism and anosmia or hyposmia. To date, 4 different genes have been identified as responsible for the presence of KS; however, in many cases no mutations have been found in any of these genes. Herein, we report the molecular findings regarding the analysis of fibroblast growth factor receptor 1 (FGFR1), prokineticin receptor 2 (PROKR2), and prokineticin (PROK2) in patients with KS. Twenty-four patients with KS were studied in whom mutations in KAL1 had been investigated previously. Polymerase chain reaction products from FGFR1, PROKR2, and PROK2 were sequenced and mutations were sought in the open reading frame of the 3 genes. Two patients presented a heterozygous T-to-G transversion in exon 2 (c.518T>G) of the PROKR2, which results in a leucine-to-arginine substitution at codon 173. Our results strengthen the hypothesis of possible digenic inheritance in some patients with KS. Likewise, our data extend previous reports demonstrating that PROKR2 plays a role in the etiology of this syndrome.

Basal and gonadotropin-releasing hormone-releasable serum follicle-stimulating hormone charge isoform distribution and in vitro biological-to-immunological ratio in male puberty.

Follicle-stimulating hormone is synthesized and secreted as a mixture of heterogeneous isoforms that differ from each other in carbohydrate structure, biological potency, and plasma half-life. The relative abundance of the FSH isoforms will depend on the endocrine status of the donor at the time of sample collection. In the present study, we attempted to define the impact of the changing endocrine milieu characteristic of male puberty on the charge heterogeneity and plasma half-life of the serum FSH isoforms released under endogenous and exogenous GnRH drives, and examined whether such a varying hormone milieu modifies the capability of the circulating hormone to trigger intracellular signal transduction at the human FSH receptor level. Forty healthy male subjects at Tanner stages (Ts) 1 to 5 were sampled at 10 min intervals for 10 h. Serum from successive samples collected across 2–4 h intervals containing FSH released under basal, low-dose (10 µg), and high-dose (90 µg) exogenous GnRH-stimulated conditions was subjected to preparative chromatofocusing and tested for bioactivity employing a homologous cell in vitro bioassay system. Deconvolution analysis was applied to estimate the apparent endogenous FSH plasma half-life in samples obtained after administration of low-dose exogenous GnRH. Under all conditions studied, serum FSH charge isoforms were distributed along a pH range of 7.0 to less than 3.0. Comparisons across the different Tanner stages revealed a significant and selective increase in the ratio of FSH isoforms with elution pH values <4.50 relative to those with values ≥4.50 at Ts-2. At Ts-3, this ratio returned to that present at Ts-1, to decline thereafter during the ensuing pubertal stages. Serum bioactive FSH concentrations progressively increased (from 3.72 ± 1.3 to 16.2 ± 5.3 IU/L) throughout puberty, and in all conditions bioactive FSH concentrations exceeded those detected by a specific radioimmunoassay. The biological to immunological (B:I) FSH ratio at baseline was significantly (p<0.05) lower at Ts-1 and Ts-2 (1.33 ± 0.30 and 1.62 ± 0.34, respectively) than at more advanced stages of pubertal development (2.28 ± 0.20, 2.96 ± 0.38, and 2.77 ± 0.63 at Ts-3-, 4-, and -5, respectively) Similar differences were detected in samples containing FSH molecules released after low- and high-dose GnRH administration. The apparent endogenous FSH half-life of the deconvolved GnRH-induced FSH pulses was similar in the five study groups. These results demonstrate that the transition from infancy to sexual maturity in men is accompanied by qualitative changes in the circulating FSH isoform mixture. Although the changes in FSH glycosylation occurring throughout puberty are not of sufficient magnitude to alter the survival of the gonadotropin in the circulation, they allow preferential secretion of bioactive FSH. The enrichment of the circulating mix of FSH isoforms with highly bioactive variants throughout spontaneous puberty may potentially favor the development of spermatogenesis and acquisition of reproductive competence.

Mutation analysis of the WNT-4 gene in patients with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies in women of childbearing age and is characterized by chronic anovulation with either oligomenorrhea or amenorrhea and hyperandrogenism. The etiology of this entity remains unknown. It has been suggested that genomic variants in genes related to the regulation of androgen biosynthesis and function could be involved in genetic predisposition to PCOS. WNT-4 is a member of the WNT family of secreted molecules. Studies on female Wnt-4 knockout mice have suggested that this gene suppresses gonadal androgen synthesis in normal females. We investigated if 25 women with PCOS presented mutations in WNT-4 as the cause of their disorder. Direct sequencing of all five exons demonstrated no mutant alleles in any patient. This study demonstrates that, at least in the population studied, mutations of the open reading frame of WNT-4 gene or its intron/exon junctions are not the cause of PCOS. However, the present data do not rule out the possible existence of causative mutations in the WNT-4 gene promoter region.

Triallelic digenic mutation in the prokineticin 2 and GNRH receptor genes in two brothers with normosmic congenital hypogonadotropic hypogonadism

Abstract Purpose/aim of the study: To date, different genes have been identified as responsible for the presence of normosmic congenital hypogonadotropic hypogonadism (nCHH). Herein, we report the molecular findings regarding the analysis of PROK2, in two brothers with nCHH. Subjects and methods: Two siblings with nCHH, in whom mutations in GNRHR, PROKR2 and FGFR1 had been investigated previously, as well as their family were studied. DNA was amplified by PCR and sequenced for the PROK2 gene. Controls were analyzed by restriction fragment-length polymorphism. The structure of PROK2 and its mutant protein were compared using a protein molecular model. Results: Both affected siblings exhibited a heterozygous p.R117W mutation in PROK2, while their mother was a heterozygous carrier and their father, an unaffected brother and their sister were homozygous wild type. Besides, both patients presented a homozygous p.E90K mutation in GNRHR that had been previously reported. Conclusions: We found a novel mutation in PROK2 in two siblings in whom a mutation in the GNRHR gene had been previously reported.

Gonadotropin-Releasing Hormone Receptor Gene, Mutation of

The gonadotropin-releasing hormone (GnRH) receptor is a plasma membrane glycoprotein that mediates the binding of GnRH and its intracellular signaling. Mutations in the GnRH receptor gene may lead to structural alterations of the receptor protein and, consequently, to abnormal GnRH receptor function (binding or effector coupling) or cellular distribution.

Duplication of SOX9 associated with 46,XX ovotesticular disorder of sex development

RESEARCH QUESTION The purpose of the present study was to investigate whether ten unrelated SRY-negative individuals with this sex differentiation disorder presented a double dose of SOX9 as the cause of their disease. DESIGN Ten unrelated SRY-negative 46,XX ovotesticular disorder of sexual development (DSD) subjects were molecularly studied. Multiplex-ligation dependent probe amplification (MLPA) and quantitative real-time PCR analysis (qRT-PCR) for SOX9 were performed. RESULTS The MLPA analysis demonstrated that one patient presented a heterozygous duplication of the entire SOX9 coding region (above 1.3 value of peak ratio), as well as at least a ~ 483 kb upstream duplication. Moreover, no duplication of other SOX9 probes was observed corresponding to the region between -1007 and -1500 kb upstream. A qRT-PCR analysis showed a duplication of at least -581 kb upstream and ~1.63 kb of the coding region that encompasses exon 3. The limits of the duplication were mapped approximately from ~71539762 to 72122741 of Chr17. No molecular abnormalities were found in the remaining nine patients. CONCLUSION This study is thought to be the first report regarding a duplication of SOX9 that is associated with the presence of 46,XX ovotesticular DSD, encompassing at least -581 kb upstream, and the almost entire coding region of the gene.