Species: mouse
Mutation name: None
type: null mutation
fertility: subfertile
Comment: Basonuclin: a novel mammalian maternal-effect gene. Ma J et al. Basonuclin is a zinc-finger protein found in abundance in oocytes. It qualifies as a maternal-effect gene because the source of pre-implantation embryonic basonuclin is maternal. Using a transgenic-RNAi approach, we knocked down basonuclin specifically in mouse oocytes, which led to female sub-fertility. Basonuclin deficiency in oocytes perturbed both RNA polymerase I- and II-mediated transcription, and oocyte morphology was affected (as evidenced by cytoplasmic and cell surface abnormalities). Some of the affected oocytes, however, could still mature to and arrest at metaphase II, and be ovulated. Nevertheless, fertilized basonuclin-deficient eggs failed to develop beyond the two-cell stage, and this pre-implantation failure accounted for the sub-fertility phenotype. These results suggest that basonuclin is a new member of the mammalian maternal-effect genes and, interestingly, differs from the previously reported mammalian maternal-effect genes in that it also apparently perturbs oogenesis.

Species: human
Mutation name:
type: naturally occurring
fertility: subfertile
Comment: High-resolution array-CGH analysis on 46,XX patients affected by early onset primary ovarian insufficiency discloses new genes involved in ovarian function. Bestetti I et al. (2019) Can high resolution array-CGH analysis on a cohort of women showing a primary ovarian insufficiency (POI) phenotype in young age identify copy number variants (CNVs) with a deleterious effect on ovarian function? This approach has proved effective to clarify the role of CNVs in POI pathogenesis and to better unveil both novel candidate genes and pathogenic mechanisms. POI describes the progression toward the cessation of ovarian function before the age of 40 years. Genetic causes are highly heterogeneous and despite several genes being associated with ovarian failure, most of genetic basis of POI still needs to be elucidated. The current study included 67 46,XX patients with early onset POI (<19 years) and 134 control females recruited between 2012 and 2016 at the Medical Cytogenetics and Molecular Genetics Lab, IRCCS Istituto Auxologico Italiano. High resolution array-CGH analysis was carried out on POI patients' DNA. Results of patients and female controls were analyzed to search for rare CNVs. All variants were validated and subjected to a gene content analysis and disease gene prioritization based on the present literature to find out new ovary candidate genes. Case-control study with statistical analysis was carried out to validate our approach and evaluate any ovary CNVs/gene enrichment. Characterization of particular CNVs with molecular and functional studies was performed to assess their pathogenic involvement in POI. We identified 37 ovary-related CNVs involving 44 genes with a role in ovary in 32 patients. All except one of the selected CNVs were not observed in the control group. Possible involvement of the CNVs in POI pathogenesis was further corroborated by a case-control analysis that showed a significant enrichment of ovary-related CNVs/genes in patients (P = 0.0132; P = 0.0126). Disease gene prioritization identified both previously reported POI genes (e.g. BMP15, DIAPH2, CPEB1, BNC1) and new candidates supported by transcript and functional studies, such as TP63 with a role in oocyte genomic integrity and VLDLR which is involved in steroidogenesis. ClinVar database (http://www.ncbi.nlm.nih.gov/clinvar/); accession numbers SCV000787656 to SCV000787743. This is a descriptive analysis for almost all of the CNVs identified. Inheritance studies of CNVs in some non-familial sporadic cases was not performed as the parents' DNA samples were not available. Addionally, RT-qPCR analyses were carried out in few cases as RNA samples were not always available and the genes were not expressed in blood. Our array-CGH screening turned out to be efficient in identifying different CNVs possibly implicated in disease onset, thus supporting the extremely wide genetic heterogeneity of POI. Since almost 50% of cases are negative rare ovary-related CNVs, array-CGH together with next generation sequencing might represent the most suitable approach to obtain a comprehensive genetic characterization of POI patients. Supported by Italian Ministry of Health grants 'Ricerca Corrente' (08C203_2012) and 'Ricerca Finalizzata' (GR-2011-02351636, BIOEFFECT) to IRCCS Istituto Auxologico Italiano.//////////////////

Species: None
Mutation name:
type: null mutation
fertility: infertile - ovarian defect
Comment: Basonuclin-2 requirements for zebrafish adult pigment pattern development and female fertility. Lang MR et al. (2010) Relatively little is known about the generation of adult form. One complex adult trait that is particularly amenable to genetic and experimental analysis is the zebrafish pigment pattern, which undergoes extensive remodeling during post-embryonic development to form adult stripes. These stripes result from the arrangement of three classes of neural crest-derived pigment cells, or chromatophores: melanophores, xanthophores, and iridophores. Here, we analyze the zebrafish bonaparte mutant, which has a normal early pigment pattern but exhibits a severe disruption to the adult stripe pattern. We show that the bonaparte mutant phenotype arises from mutations in basonuclin-2 (bnc2), encoding a highly conserved, nuclear-localized zinc finger protein of unknown function. We show that bnc2 acts non-autonomously to the melanophore lineage and is expressed by hypodermal cells adjacent to chromatophores during adult pigment pattern formation. In bonaparte (bnc2) mutants, all three types of chromatophores differentiate but then are lost by extrusion through the skin. We further show that while bnc2 promotes the development of two genetically distinct populations of melanophores in the body stripes, chromatophores of the fins and scales remain unaffected in bonaparte mutants, though a requirement of fin chromatophores for bnc2 is revealed in the absence of kit and colony stimulating factor-1 receptor activity. Finally, we find that bonaparte (bnc2) mutants exhibit dysmorphic ovaries correlating with infertility and bnc2 is expressed in somatic ovarian cells, whereas the related gene, bnc1, is expressed within oocytes; and we find that both bnc2 and bnc1 are expressed abundantly within the central nervous system. These findings identify bnc2 as an important mediator of adult pigment pattern formation and identify bonaparte mutants as an animal model for dissecting bnc2 functions.//////////////////

Species: mouse
Mutation name:
type: null mutation
fertility: None
Comment: Basonuclin 1 deficiency causes testicular premature aging: BNC1 cooperates with TAF7L to regulate spermatogenesis. Li JY et al. (2020) Basonuclin (BNC1) is expressed primarily in proliferative keratinocytes and gametogenic cells. However, its roles in spermatogenesis and testicular aging were not clear. Previously we discovered a heterozygous BNC1 truncation mutation in a premature ovarian insufficiency pedigree. In this study, we found that male mice carrying the truncation mutation exhibited progressively fertility loss and testicular premature aging. Genome-wide expression profiling and direct binding studies (by chromatin immunoprecipitation sequencing) with BNC1 in mouse testis identified several spermatogenesis-specific gene promoters targeted by BNC1 including kelch-like family member 10 (Klhl10), testis expressed 14 (Tex14), and spermatogenesis and centriole associated 1 (Spatc1). Moreover, biochemical analysis showed that BNC1 was associated with TATA-box binding protein-associated factor 7 like (TAF7L), a germ cell-specific paralogue of the transcription factor IID subunit TAF7, both in vitro and in testis, suggesting that BNC1 might directly cooperate with TAF7L to regulate spermatogenesis. The truncation mutation disabled nuclear translocation of the BNC1/TAF7L complex, thus, disturbing expression of related genes and leading to testicular premature aging. Similarly, expressions of BNC1, TAF7L, Y-box-binding protein 2 (YBX2), outer dense fiber of sperm tails 1 (ODF1), and glyceraldehyde-3-phosphate dehydrogenase, spermatogenic (GAPDHS) were significantly decreased in the testis of men with non-obstructive azoospermia. The present study adds to the understanding of the physiology of male reproductive aging and the mechanism of spermatogenic failure in infertile men.//////////////////

Species: human
Mutation name:
type: naturally occurring
fertility: infertile - ovarian defect
Comment: Basonuclin 1 deficiency is a cause of primary ovarian insufficiency. Zhang D et al. (2019) Primary ovarian insufficiency (POI) leads to infertility and premature menopause in young women. The genetic etiology of this disorder remains unknown in most patients. Using whole exome sequencing of a large Chinese POI pedigree, we identified a heterozygous 5 bp deletion inducing a frameshift in BNC1, which is predicted to result in a non-sense-mediated decay or a truncated BNC1 protein. Sanger sequencing identified another BNC1 missense mutation in 4 of 82 idiopathic patients with POI, and the mutation was absent in 332 healthy controls. Transfection of recombinant plasmids with the frameshift mutant and separately with the missense mutant in HEK293T cells led to abnormal nuclear localization. Knockdown of BNC1 was found to reduce BMP15 and p-AKT levels and to inhibit meiosis in oocytes. A female mouse model of the human Bnc1 frameshift mutation exhibited infertility, significantly increased serum follicle-stimulating hormone, decreased ovary size and reduced follicle numbers, consistent with POI. We report haploinsufficiency of BNC1 as an etiology of human autosomal dominant POI.//////////////////