Nouha Bouayed Abdelmoula

Skewed X-chromosome inactivation pattern in SRY positive XX maleness: a case report and review of literature.

XX maleness is the most common condition in which testes develop in the absence of a cytogenetically detectable Y chromosome. Using fluorescence in situ hybridization (FISH) or PCR, it was possible to detect the transfer of Yp fragments including SRY gene to the terminal part of X chromosome in the majority of XX males. We report a 32-year-old-male in whom a seminal analysis showed azoospermia, an X chromatin analysis showed 44% of Barr body positive nuclei and a chromosomal analysis revealed a 46,XX karyotype. Physical examination showed a normal sexual development and bilateral small testes. Hormonal studies revealed hypergonadotropic hypogonadism. Testis histological examination showed a profile of Sertoli Only Cell Syndrome. FISH study ruled out the presence of a Y-bearing cell line, and confirmed translocation of SRY to Xp terminal part. In order to confirm that the complete masculinized phenotype was related to a preferential inactivation of the no rearranged X chromosome, X-chromosome inactivation patterns (XCIP) were studied by analysis of methylation status of the androgen receptor gene. Highly skewed XCIP was observed by greater than 90% preferential inactivation involving one of the two X chromosomes, suggesting that the SRY-bearing X chromosome was the preferentially active X allowing for sufficient SRY expression for complete masculinization.

Endocrine disruption and ovarian morphometric responses in rats following exposure to tetradifon.

We have investigated whether exposure to tetradifon causes ovary injuries, disrupts folliculogenesis in rat and whether ovary hormones (estrogen and progesterone) to be affected by this endocrine-active agent. Female rats were exposed orally to a dose of 28.9 mg/kg/day for 6 or 12 weeks. After sacrifice, ovary glands were examined for morphometric changes. The serums were used to determine levels of 17beta-estradiol and progesterone. Results showed no sign of toxicity. However, tetradifon promoted a significant increase in the percentage of atretic follicles in the 12-weeks treated rats. Number and the diameter of mature follicles (tertiary and preovulatory) were markedly diminished together with a reduction of the relative weight of ovaries. Compared with controls, the treated rats exhibited significant reduction in serum 17beta-estradiol and progesterone levels. These results suggest an endocrine disruption by tetradifon which may interfere with ovarian follicles development in rat.

Erythrocytes oxidative damage and hematological effects of 2,4,4',5-tetrachlorodiphenyl sulfone in rats.

The effects of subchronic exposure to tetrachlorodiphenyl sulfone (TCDS) on hematological parameters [white blood cells (WBC), red blood cells (RBC), mean cell volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), hemoglobin (Hb) and hematocrite (Ht) levels] were examined. Oxidative stress in erythrocytes was also assessed by measuring thiobarbituric acid reactive substances (TBARS) and enzyme antioxidant activities [superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)]. TCDS was administered orally, dissolved in water, ad libitum to 12 female rats at 28.9 mg/kg/day for 6 or 12 weeks. Results showed that TCDS induced significant decreases in RBC, Hb, and Ht. Whereas MCV, MCH, and MCHC remain unchanged and WBC increased only in the second period of the study. Moreover erythrocyte TBARS level increased, and antioxidant enzyme (SOD, GPx, and CAT) activities decreased. We concluded that TCDS intoxication promotes erythrocyte oxidative damage and disrupt hematological constituents in rats.

Left-sided congenital heart lesions in mosaic Turner syndrome

In the era of the diseasomes and interactome networks, linking genetics with phenotypic traits in Turner syndrome should be studied thoroughly. As a part of this stratagem, mosaicism of both X and Y chromosome which is a common finding in TS and an evaluation of congenital heart diseases in the different situations of mosaic TS types, can be helpful in the identification of disturbed sex chromosomes, genes and signaling pathway actors. Here we report the case of a mosaic TS associated to four left-sided CHD, including BAV, COA, aortic aneurysms and dissections at an early age. The mosaicism included two cell lines, well-defined at the cytogenetic and molecular levels: a cell line which is monosomic for Xp and Xq genes (45,X) and another which is trisomic for pseudoautosomal genes that are present on the X and Y chromosomes and escape X inactivation: 45,X[8]/46,X,idic(Y)(pter→q11.2::q11.2→pter)[42]. This case generates two hypotheses about the contribution of genes linked to the sex chromosomes and the signaling pathways involving these genes, in left-sided heart diseases. The first hypothesis suggests the interaction between X chromosome and autosomal genes or loci of aortic development, possibly dose-dependent, and which could be in the framework of TGF-β-SMAD signaling pathways. The second implies that left-sided congenital heart lesions involve sex chromosomes loci. The reduced dosage of X chromosome gene(s), escaping X inactivation during development, contributes to this type of CHD. Regarding our case, these X chromosome genes may have homologues at the Y chromosome, but the process of inactivation of the centromeres of the isodicentric Y spreads to the concerned Y chromosome genes. Therefore, this case emerges as an invitation to consider the mosaics of Turner syndrome and to study their phenotypes in correlation with their genotypes to discover the underlying developmental and genetic mechanisms, especially the ones related to sex chromosomes.

Wilson disease, genotype and infertility: is there a correlation?

Wilson disease (WD; OMIM#277900) is a rare autosomal recessive disorder of copper metabolism, caused by mutations in the ATP7B gene (ATPase, Cu transporting, beta polypeptide; OMIM#606882; 21 exons) and leading to hepatic or neurologic disease. The wide spectrum of symptoms in patients with Wilson’s disease raised the question whether these features are determined by the type of the ATP7B mutation. To date, more than 500 mutations have been identified in patients with Wilson disease [1], and genetic studies are also becoming available for clinical use, but the utility of direct mutation analysis is limited. In this report, we try to establish relationship between phenotype (WD) and genotype (mutation through ATP7B gene). It is about a nonconsanguineous couple from Sfax in south Tunisia, who attended our genetic counselling and underwent a genetic testing for primary infertility since 17 years and failures of assisted reproductive technology (ART). Karyotype was normal in both partners, semen analysis reveal a moderate Oligo-astheno-teratozoospermia since 18 years, hormonal status (FSH, LH and testosterone) was normal, so, an idiopathic male infertility was suspected. WD was diagnosed in the man at 24 years, based on neurologic symptoms and elevated 24-h urinary copper, and a specific treatment mainly by D-penicillamine (DPA) was indicated. For genetic diagnosis of WD, peripheral blood was firstly collected from the patient after obtaining an informed consent. Second, the genomic DNA was extracted from white blood cells by standard phenol–chloroform method. Finally, the ATP7B gene was amplified and sequenced using automated sequencer (ABI, Applied Biosystems, CA, USA). The patient was a compound heterozygote for both the H1069Q and H642G, respectively, in exon 14 and 6 of ATP7B gene. Similar familial case with infertility and WD was reported. The same mutation is found in relatives (Fig. 1). Since multiple failures of ART; a control semen analysis was indicated which revealed a severely altered sperm quality (from moderate Oligo-astheno-teratozoospermia to severe teratospermia) although clinical amelioration with DPA. On my knowledge, this is the first reported cases of infertility in WD. We speculate that the pathophysiological disturbances leading to organ damage in WD are not only for the liver and the brain. Here, the testis tissue is altered mainly by copper toxicity which promote oxidative stress. Thus, increased markers of oxidative damage, including lipid peroxidation, damaged proteins and DNA, might be implicated in the mechanism of infertility in WD [2]. Furthermore, the testis copper concentration and study of DNA fragmentation of sperm are necessary to confirm the association between infertility and copper toxicity during the disease. R. Frikha (&) N. B. Abdelmoula T. Rebai Laboratory of Histology, Faculty of Medicine of Sfax, 3029 Sfax, Tunisia e-mail: frikha_rim@yahoo.fr

Screening for Cytogenetic and Molecular Chromosome Rearrangements in Tunisian Children With Conotruncal Heart Defects

Background: Conotruncal heart defects are cardiovascular malformations that have most been associated with chromosomal 22q11.2 microdeletion. Methods: To estimate frequency and investigate the clinical features of these microdeletions in unselected patients with conotruncal heart defects, a total of 26 patients originating from southern Tunisia had been prospectively evaluated through cytogenetic and molecular studies. The clinical analysis was performed according to a specific clinical protocol for the diagnosis of congenital cardiovascular malformations. A molecular cytogenetic technique was undertaken by fluorescence in situ hybridization (FISH) using 2 probes: LSI DiGeorge N25 (D22S75) region probe N25/ARSA, and LSI DiGeorge/ VCFS region probe TUPLE1/ARSA. cytogenetic analysis with RHG banding was carried out to detect chromosome rearrangements. All patients have normal karyotype 46,XX or 46,XY. Results: The frequency of the 22q11.2 microdeletion in the subjects carrying conotruncal heart defects with or without extracardiac signs of our series is thus estimated at 3.85% (1/26). Conclusion: The microdeleted subject is carrying a tetralogy of Fallot.