Double complex mutations involving F8 and FUNDC2 caused by distinct break-induced replication
HUMAN MUTATION
Authors: Sheen, Campbell R.; Jewell, Ursula R.; Morris, Christine M.; Brennan, Stephen O.; Ferec, Claude; George, Peter M.; Smith, Mark P.; Chen, Jian-Min
Abstract
Genomic rearrangements are a well-recognized cause of genetic disease and can be formed by a variety of mechanisms. We report a complex rearrangement causing severe hemophilia A, identified and further characterized using a range of PCR-based methods, and confirmed using array-comparative genomic hybridization (array-CGH). This rearrangement consists of a 15.5-kb deletion/16-bp insertion located 0.6 kb from a 28.1-kb deletion/263-kb insertion at Xq28 and is one of the most complex rearrangements described at a DNA sequence level. We propose that the rearrangement was generated by distinct but linked cellular responses to double strand breakage, namely break-induced replication (13111) and a novel model of break-induced serial replication slippage (SRS). The copy number of several genes is affected by this rearrangement, with deletion of part of the Factor VIII gene (F8, causing hemophilia A) and the FUNDC2 gene, and duplication of the TMEM185A, HSFXl, MAGEA9, and MAGEA11 genes. As the patient exhibits no clinically detectable phenotype other than hemophilia A, it appears that the biological effects of the other genes involved are not dosage. dependent. This investigation has provided novel insights into processes of DNA repair including BIR and the first description of SRS during repair in a pathological context. Hum Mutat 28(12), 1198-1206, 2007. (c) 2007 Wiley-Liss, Inc.
Recurrent X chromosome-linked deletions: discovery of new genetic factors in male infertility
JOURNAL OF MEDICAL GENETICS
Authors: Lo Giacco, D.; Chianese, C.; Ars, E.; Ruiz-Castane, E.; Forti, G.; Krausz, C.
Abstract
Background The role of X-linked genes and copy-number variations (CNVs) in male infertility remains poorly explored. Our previous array-CGH analyses showed three recurrent deletions in Xq exclusively (CNV67) and prevalently (CNV64, CNV69) found in patients. Molecular and clinical characterisation of these CNVs was performed in this study. Methods 627 idiopathic infertile patients and 628 controls were tested for each deletion with PCR+/-. We used PCR+/- to map deletion junctions and long-range PCR and direct sequencing to define breakpoints. Results CNV64 was found in 5.7% of patients and in 3.1% of controls (p=0.013; OR=1.89; 95% CI 1.1 to 3.3) and CNV69 was found in 3.5% of patients and 1.6% of controls (p=0.023; OR=2.204; 95% CI 1.05 to 4.62). For CNV69 we identified two breakpoints, types A and B, with the latter being significantly more frequent in patients than controls (p=0.011; OR=9.19; 95% CI 1.16 to 72.8). CNV67 was detected exclusively in patients (1.1%) and was maternally transmitted. The semen phenotype of one carrier (11-041) versus his normozoospermic non-carrier brother strongly indicates a pathogenic effect of the deletion on spermatogenesis. MAGEA9, an ampliconic gene reported as independently acquired on the human X chromosome with exclusive physiological expression in the testis, is likely to be involved in CNV67. Conclusions We provide the first evidence for X chromosome-linked recurrent deletions associated with spermatogenic impairment. CNV67, specific to spermatogenic anomaly and with a frequency of 1.1% in oligo/azoospermic men, resembles the AZF regions on the Y chromosome with potential clinical implications.