Systematic Analysis of CCNO Variants in a Defined Population: Implications for Clinical Phenotype and Differential Diagnosis
HUMAN MUTATION
Authors: Amirav, Israel; Wallmeier, Julia; Loges, Niki T.; Menchen, Tabea; Pennekamp, Petra; Mussaffi, Huda; Abitbul, Revital; Avital, Avraham; Bentur, Lea; Dougherty, Gerard W.; Nael, Elias; Lavie, Moran; Olbrich, Heike; Werner, Claudius; Kintner, Chris; Omran, Heymut
Abstract
Reduced generation of multiple motile cilia (RGMC) is a novel chronic destructive airway disease within the group of mucociliary clearance disorders with only few cases reported. Mutations in two genes, CCNO and MCIDAS, have been identified as a cause of this disease, both leading to a greatly reduced number of cilia and causing impaired mucociliary clearance. This study was designed to identify the prevalence of CCNO mutations in Israel and further delineate the clinical characteristics of RGMC. We analyzed 170 families with mucociliary clearance disorders originating from Israel for mutations in CCNO and identified two novel mutations (c.165delC, p.Gly56Alafs*38; c.638T>C, p.Leu213Pro) and two known mutations in 15 individuals from 10 families (6% prevalence). Pathogenicity of the missense mutation (c.638T>C, p.Leu213Pro) was demonstrated by functional analyses in Xenopus. Combining these 15 patients with the previously reported CCNO case reports revealed rapid deterioration in lung function, an increased prevalence of hydrocephalus (10%) as well as increased female infertility (22%). Consistent with these findings, we demonstrate that CCNO expression is present in murine ependyma and fallopian tubes. CCNO is mutated more frequently than expected from the rare previous clinical case reports, leads to severe clinical manifestations, and should therefore be considered an important differential diagnosis of mucociliary clearance disorders.
A genomics approach to females with infertility and recurrent pregnancy loss
HUMAN GENETICS
Authors: Maddirevula, Sateesh; Awartani, Khalid; Coskun, Serdar; AlNaim, Latifa F.; Ibrahim, Niema; Abdulwahab, Firdous; Hashem, Mais; Alhassan, Saad; Alkuraya, Fowzan S.
Abstract
Infertility affects 10% of reproductive-age women and is extremely heterogeneous in etiology. The genetic contribution to female infertility is incompletely understood, and involves chromosomal and single-gene defects. Our aim in this study is to decipher single-gene causes in infertile women in whom endocrinological, anatomical, and chromosomal causes have been excluded. Our cohort comprises women with recurrent pregnancy loss and no offspring from spontaneous pregnancies (RPL, n = 61) and those who never achieved clinical pregnancy and were referred for in vitro fertilization [primary infertility (PI), n = 14]. Whole-exome sequencing revealed candidate variants in 14, which represents 43% of those with PI and 13% of those with RPL. These include variants in previously established female infertility-related genes (TLE6, NLRP7, FSHR, and ZP1) as well as genes with only tentative links in the literature (NLRP5). Candidate variants in genes linked to primary ciliary dyskinesia (DNAH11 and CCNO) were identified in individuals with and without systemic features of the disease. We also identified variants in genes not previously linked to female infertility. These include one homozygous variant each in CCDC68, CBX3, CENPH, PABPC1L, PIF1, PLK1, and REXO4, which we propose as candidate genes for infertility based on their established biology or compatible animal models. Our study expands the contribution of single genes to the etiology of PI and RPL, improves the precision of disease classification at the molecular level, and offers the potential for future treatment and development of human genetics-inspired fertility regulators.