Identification of a missense variant in CLDN2 in obstructive azoospermia.

Obstructive azoospermia (OA), defined as an obstruction in any region of the male genital tract, accounts for 40% of all azoospermia cases. Of all OA cases, ~30% are thought to have a genetic origin, however, hitherto, the underlying genetic etiology of the majority of these cases remain unknown. To address this, we took a family-based whole-exome sequencing approach to identify causal variants of OA in a multiplex family with epidydimal obstruction. A novel gain-of-function missense variant in CLDN2 (c.481G>C; p.Gly161Arg) was found to co-segregate with the phenotype, consistent with the X-linked inheritance pattern observed in the pedigree. To assess the pathogenicity of this variant, the wild and mutant protein structures were modeled and their potential for strand formation in multimeric form was assessed and compared. The results showed that dimeric and tetrameric arrangements of Claudin-2 were not only reduced, but were also significantly altered by this single residue change. We, therefore, envisage that this amino acid change likely forms a polymeric discontinuous strand, which may lead to the disruption of tight junctions among epithelial cells. This missense variant is thus likely to be responsible for the disruption of the blood-epididymis barrier, causing dislodged epithelial cells to clog the genital tract, hence causing OA. This study not only sheds light on the underlying pathobiology of OA, but also provides a basis for more efficient diagnosis in the clinical setting.

Outcome of isolated fetal choroid plexus cyst detected in prenatal sonography among infertile patients referred to Royan Institute: A 3-year study.

BACKGROUND: Several studies have assessed the correlation of fetal choroid plexus cyst (CPC) and the risk of congenital anomalies, but few ones have discussed isolated CPC (with no other abnormal sonographic finding). OBJECTIVE: The aim of this study was to determine the outcome of isolated fetal choroid plexus cyst and to specify its clinical significance. MATERIALS AND METHODS: This cross sectional study was carried out at Royan Institute in Tehran, Iran, between April 2009 and December 2012. All prenatal sonographies in this period of time were assessed using a computerized database and fetuses who had isolated CPC were recruited in the study. Sonography reports, mother serum screening test results, fetal echocardiography and amniocentesis were evaluated until birth. A follow-up phone call was made to all individuals to learn about the neonatal outcomes. RESULTS: Overall, 6240 prenatal sonographies were performed in this setting during this period. Isolated CPC was detected in 64 fetuses. The results of double test (N=30), triple test (N=5) and fetal echocardiography (N =24) were normal. Quadruple test result showed 3 abnormal out of 29 cases that all had normal karyotypes. Four samples were dropped out due to premature rupture of membranes (N=3) and intrauterine fetal death (N=1). It was found that the outcomes of all remaining fetuses (N=60) were normal and no anomaly ones were seen until birth. CONCLUSION: Isolated CPC is a benign regressive condition with no clinical significance.