Identification et caractérisation de gènes impliqués dans l'infertilité masculine

Près de 15% des couples sont confrontés à des problèmes d'infertilité. Dans près de la moitié des cas, une composante masculine est retrouvée, avec souvent une anomalie des paramètres du spermogramme montrant une diminution de la qualité du sperme. L'étiologie de la grande majorité des infertilités masculines reste inconnue et une origine génétique est probablement responsable d'une proportion importante des troubles de la spermatogénèse. Ce travail comporte deux parties: dans la 1ère partie, l'analyse d'une large cohorte de patients (n=87), nous a permis d'identifier deux nouvelles mutations du gène AURKC. La mutation [c.36-2A>G] a été identifiée uniquement à l'état hétérozygote chez deux frères et le 2ème variant identifié [p.Y248*]: est une mutation récurrente retrouvée chez 11 patients non apparenté d'origine maghrébine et européenne. La 2ème partie de notre étude a été réalisée sur 20 patients infertiles présentant un phénotype homogène d'anomalies flagellaire de type flagelles courts, absents et de calibre irrégulier associé a une asthénozoospermie. Nous avons appliqué la stratégie d'homozygotie par filiation qui a permis de mettre en évidence deux régions d'homozygoties communes: la 1ère région, située sur le chromosome 3, est commune à 9/20 patients et la 2ème sur le chromosome 20 commune à 13/20 patients. Trois gènes candidats présents dans ces régions ont été sélectionnés : les gènes KIF9, SPAG4 et DNAH1. Le séquençage du gène DNAH1 a permis de mettre en évidence des mutations de type faux-sens [c.3877G>A], run-on [c.12796 T>C] et d'épissage [c.5094+1G>A] [c.11958-1G>A]. L'absence de la protéine DNAH1 a pu être mise en évidence par immunomarquage sur les spermatozoïdes d'un patients porteur de la mutation [c.11958-1G>A] et confirme la dégradation du transcrit muté par NMD également observé. Les analyses par microscopie électronique sur les spermatozoïdes d'un patient de la cohorte ont permis de mettre en évidence des anomalies de la structure de l'axonème. Cette étude précise le diagnostic d'infertilité masculine et élargit les connaissances sur les gènes impliquées dans la spermatogenèse.About 15% of couples are confronted with infertility problems. In half of the cases, a male factor component is found, often with abnormal semen parameters. The etiology of the large majority of male infertility remains unknown and genetic origin is probably responsible of a significant proportion of spermatogenesis disorders. This work comprises two parts: in the first part, the analysis of a large cohort of patients (n = 87), allowed us to identify two new mutations in AURKC gene. A splice site mutation [c.36-2A> G] was identified in only two brothers and the second variant identified [p.Y248*] is a recurrent mutation found in 11 unrelated patients. The second part of our study was carried out on 20 infertile patients with flagellar abnormalities associated with asthenozoospermia. We have applied the strategy of homozygosity by descent who has bring out two regions of homozygosity: the first region, located on chromosome 3, is common for 9/20 patients and the second one, located on chromosome 20, is common for 13/20 patients. Three candidate genes present in these regions were selected: KIF9, SPAG4 and DNAH1. Sequencing of DNAH1 gene has bring out three type of mutations: missense mutation [c.3877G> A], run-on mutation [c.12796 T> C] and splice site mutation [c.5094 +1 G> A] [c.11958-1G> A]. The absence of dnah1 protein has been shown by immunostaining of spermatozoa of a patient carrier the mutation [c.11958-1G> A] and confirms the degradation of the mutated transcript by NMD. An electron microscopic analysis of spermatozoa of one patient of the cohort reveals axoneme abnormalities. This study clarifies the diagnosis of male infertility and broadens the knowledge of the genes involved in spermatogenesis.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Hepatoid adenocarcinoma of the gallbladder

Hepatoid adenocarcinoma is a rare variant of extrahepatic adenocarcinoma which behaves like hepatocellular carcinoma in morphology and functionality

An unusual pigmented skin lesion on the nipple‐areola area

Abstract Considering the rarity and underdiagnoses of this disorder, a pigmented and hyperkeratotic skin lesion located on the trunk, resembling to acanthosis nigricans should always be investigated for terra firma‐forme dermatosis (TFFD) and thus alcohol must be applied. TFFD should be known among dermatologists and can be easily diagnosed and treated with isopropyl alcohol

Unusual malar rash with ulceration: What can we expect?

Abstract Considering the clinical polymorphism of the disease, longstanding skin lesions located on the face, resembling erysipelas in an endemic area should always be investigated for CL and thus, atypical presentations should be kept in mind

Unilateral hyperpigmented lesion of the breast

Abstract Muco‐cutaneous melanosis is a benign entity with no progression. Although, dermoscopic features may help to differentiate melanosis from malignant pigmented diseases, histopathology remains crucial for the confirming of melanosis of the nipple and areola. Herein, we represent a new case of melanosis of the areola and we describe its clinico‐pathological aspects

A Tunisian patient with CLCN2‐related leukoencephalopathy

Abstract CLCN2‐related leukoencephalopathy (CC2L OMIM#: 615651) is a recently identified rare disorder. It is caused by autosomal recessive mutations in the CLCN2 gene and leads to the dysfunction of its encoded CLC‐2 chloride channel protein with characteristic brain MRI features of leukoencephalopathy. We report the first Tunisian patient with clinical features of ClCN‐2‐related leukoencephalopathy. A 54‐year‐old female with a family history of leukemia, male infertility, motor disability, and headaches who initially presented with a tension‐type headache and normal physical examination. At the follow‐up, she developed mild gait ataxia and psycho‐cognitive disturbances. A previously reported homozygous NM_004366.6(CLCN2):c.1709G > A (p.Trp570Ter) stop gained mutation was identified. This report expands the knowledge related to CC2L and highlights the clinical features in affected individuals of African descent

High frequency of exon 15 deletion in the FANCA gene in Tunisian patients affected with Fanconi anemia disease: implication for diagnosis.

International audienceTunisian population is characterized by its heterogeneous ethnic background and high rate of consanguinity. In consequence, there is an increase in the frequency of recessive genetic disorders including Fanconi anemia (FA). The aim of this study was to confirm the existence of a founder haplotype among FA Tunisian patients and to identify the associated mutation in order to develop a simple tool for FA diagnosis. Seventy-four unrelated families with a total of 95 FA patients were investigated. All available family members were genotyped with four microsatellite markers flanking FANCA gene. Haplotype analysis and homozygosity mapping assigned 83 patients belonging to 62 families to the FA-A group. A common haplotype was shared by 42 patients from 26 families at a homozygous state while five patients from five families were heterozygous. Among them, 85% were from southern Tunisia suggesting a founder effect. Using multiplex ligation-dependent probe amplification (MLPA) technique, we have also demonstrated that this haplotype is associated with a total deletion of exon 15 in FANCA gene. Identification of a founder mutation allowed genetic counseling in relatives of these families, better bone marrow graft donor selection and prenatal diagnosis. This mutation should be investigated in priority for patients originating from North Africa and Middle East