Miguel Xavier

Newcastle University | NCL · Institute of Genetic Medicine

Piwi-interacting RNAs (piRNAs) are crucial for transposon silencing, germ cell maturation, and fertility in male mice. Here, we report on the genetic landscape of piRNA dysfunction in humans and present 39 infertile men carrying biallelic variants in 14 different piRNA pathway genes, including PIWIL1 , GTSF1 , GPAT2, MAEL, TDRD1 , and DDX4 as novel...

Non-obstructive azoospermia (NOA) is the most severe form of male infertility and typically incurable. Defining the genetic basis of NOA has proven challenging, and the most advanced classification of NOA subforms is not based on genetics, but simple description of testis histology. In this study, we exome-sequenced over 1000 clinically diagnosed N...

De novo mutations (DNMs) play an important role in severe genetic disorders that reduce fitness. To better understand their role in disease, it is important to determine the parent‐of‐origin and timing of mutational events that give rise to these mutations, especially in sex‐specific developmental disorders such as male infertility. However, curren...

Infertility affects around 7% of the male population and can be due to severe spermatogenic failure (SPGF), resulting in no or very few sperm in the ejaculate. We initially identified a homozygous frameshift variant in FKBP6 in a man with extreme oligozoospermia. Subsequently, we screened a total of 2,699 men with SPGF and detected rare bi-allelic...

Non-obstructive azoospermia (NOA) is the most severe form of male infertility and typically incurable with current medicine. Due to the biological complexity of sperm production, defining the genetic basis of NOA has proven challenging, and to date, the most advanced classification of NOA subforms is based on simple description of testis histology....

Although the evolutionary history of the X chromosome indicates its specialization in male fitness, its role in spermatogenesis has largely been unexplored. Currently only three X chromosome genes are considered of moderate-definitive diagnostic value. We aimed to provide a comprehensive analysis of all X chromosome-linked protein-coding genes in 2...

De novo mutations (DNMs) play an important role in severe genetic disorders that reduce fitness. To better understand the role of DNMs in disease, it is important to determine the parent-of-origin and timing of the mutational events that give rise to the mutations, especially in sex-specific developmental disorders such as male infertility. However...

De novo mutations (DNMs) play an important role in severe genetic disorders that reduce fitness. To better understand the role of DNMs in disease, it is important to determine the parent-of-origin and timing of the mutational events that give rise to the mutations, especially in sex-specific developmental disorders such as male infertility. However...

STUDY QUESTION Are there more de novo mutations (DNMs) present in the genomes of children born through medical assisted reproduction (MAR) compared to spontaneously conceived children? SUMMARY ANSWER In this pilot study, no statistically significant difference was observed in the number of DNMs observed in the genomes of MAR children versus sponta...

De novo mutations are known to play a prominent role in sporadic disorders with reduced fitness. We hypothesize that de novo mutations play an important role in severe male infertility and explain a portion of the genetic causes of this understudied disorder. To test this hypothesis, we utilize trio-based exome sequencing in a cohort of 185 inferti...

Paternal exposure to environmental stressors elicits distinct changes to the sperm sncRNA profile, modifications that have significant post-fertilization consequences. Despite this knowledge, there remains limited mechanistic understanding of how paternal exposures modify the sperm sncRNA landscape. Here, we report the acute sensitivity of the sper...

BACKGROUND Human male infertility has a notable genetic component, including well-established diagnoses such as Klinefelter syndrome, Y-chromosome microdeletions and monogenic causes. Approximately 4% of all infertile men are now diagnosed with a genetic cause, but a majority (60–70%) remain without a clear diagnosis and are classified as unexplain...

Male infertility impacts millions of couples yet, the etiology of primary infertility remains largely unknown. A critical element of successful spermatogenesis is maintenance of genome integrity. Here, we present a genomic study of spermatogenic failure (SPGF). Our initial analysis (n = 176) did not reveal known gene-candidates but identified a pot...

Background: Human male infertility has a notable genetic component, including well-established diagnoses like Klinefelter syndrome, Y-chromosome microdeletions, and monogenic causes. Approximately 4% of all infertile men are now diagnosed with a genetic cause, but a vast majority (60-70%) remain without a clear diagnosis and are classified as unexp...

De novo mutations (DNMs) are known to play a prominent role in many sporadic disorders with reduced fitness. We hypothesize that DNMs play an important role in male infertility and explain a significant fraction of the genetic causes of this understudied disorder. We performed a trio-based exome-sequencing study in a unique cohort of 185 infertile...

Introduction De novo mutations (DNMs) are known to play a prominent role in sporadic disorders with reduced fitness ¹ . We hypothesize that DNMs play an important role in male infertility and explain a significant fraction of the genetic causes of this understudied disorder. To test this hypothesis, we performed trio-based exome-sequencing in a uni...

Identifying the genes causing male infertility is important to increase our biological understanding as well as the diagnostic yield and clinical relevance of genetic testing in this disorder. While significant progress has been made in some areas, mainly in our knowledge of the genes underlying rare qualitative sperm defects, the same cannot be sa...

Male infertility affects ∼7% of men, but its causes remain poorly understood. The most severe form is non-obstructive azoospermia (NOA), which is, in part, caused by an arrest at meiosis. So far, only a few validated disease-associated genes have been reported. To address this gap, we performed whole-exome sequencing in 58 men with unexplained meio...

Background Clonal haematopoiesis of indeterminate potential (CHIP) occurs when somatic mutations arise in myeloid neoplasia driver genes of haematopoietic progenitor cells, in the absence of overt cytopenia or dysplasia. The prevalence of CHIP increases with age. The most common genes affected by CHIP mutations in unselected populations are DNMT3A,...

Study question: Do all regions of the paternal genome within the gamete display equivalent vulnerability to oxidative DNA damage? Summary answer: Oxidative DNA damage is not randomly distributed in mature human spermatozoa but is instead targeted, with particular chromosomes being especially vulnerable to oxidative stress. What is known already...

Background: A defining feature of sexual reproduction is the transmission of genomic information from both parents to the offspring. There is now compelling evidence that the inheritance of such genetic information is accompanied by additional epigenetic marks, or stable heritable information that is not accounted for by variations in DNA sequence...

Oocytes are reliant on messenger RNA (mRNA) stores to support their survival and integrity during a protracted period of transcriptional dormancy as they await ovulation. Oocytes are, however, known to experience an age-associated alteration in mRNA transcript abundance, a phenomenon that contributes to reduced developmental potential. Here we have...

The Big Blue® λSelect-cII selection system has been employed along with whole-exome sequencing, to examine the susceptibility of the male germ line to mutation in two challenging situations: (i) exposure to a chemotherapeutic regime including bleomycin, etoposide and cis-platinum (BEP) and (ii) the ageing process. A 3-week exposure to BEP induced c...

Current approaches for DNA extraction and fragmentation from mammalian spermatozoa provide several challenges for the investigation of the oxidative stress burden carried in the genome of male gametes. Indeed, the potential introduction of oxidative DNA damage induced by reactive oxygen species, reducing agents (dithiothreitol or beta-mercaptoethan...

coverage.pl. Perl script constructed to calculate the read coverage by comparing the alignment positions of mapped reads against the human reference genome (GRCh38/hg39). Accuracy of the read alignment programs bowtie and bowtie 2 assessed from depth of coverage of individual base pairs. (DOCX)

parse_bowtie_alignments.pl. Perl script constructed to read and extract the mapped location of each read to the human reference genome (GRCh38/hg39), the read reference name and nucleotide sequence form the output files generated by the read alignment programs bowtie and bowtie 2. (DOCX)

clean_backgroundNoise.pl. Perl algorithm developed to remove DNA sequences classified as background noise found in negative control samples from samples containing oxidised DNA fragments extracted by antibody during the MoDIP protocol. Script generates two files, one containing the all sequences without background noise and the other with all the r...

clusterMaker.pl. Perl algorithm created to sort the mapped sequences of DNA from samples and group overlapping ones into clusters of continuous reads. The algorithm first sorts the reads by chromosome and location and then based on start and end positions of consecutive reads dynamically aggregate them into clusters. Script includes the option of a...

Spinal muscular atrophy (SMA) is a monogenic disorder that is subdivided into four different types and caused by survival motor neuron gene 1 (SMN1) deletion. Discordant cases of SMA suggest that there exist additional severity modifying factors, apart from the SMN2 gene copy number. Here we performed the first genome-wide methylation profiling of...

Drosophila larvae react against eggs from the endoparasitoid wasp Leptopilina boulardi by surrounding them in a multilayered cellular capsule. Once a wasp egg is recognized as foreign, circulating macrophage-like cells, known as plasmatocytes, adhere to the invader. After spreading around the wasp egg, plasmatocytes form cellular junctions between...

When the parasitoid wasp Leptopilina boulardi lays an egg in a Drosophila larva, phagocytic cells called plasmatocytes and specialized cells known as lamellocytes encapsulate the egg. The Drosophila β-integrin Myospheroid (Mys) is necessary for lamellocytes to adhere to the cellular capsule surrounding L. boulardi eggs. Integrins are heterodimeric...