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PubMedDate not supplied

Absence of Yq microdeletions in infertile men.

Microdeletions of the long arm of the Y chromosome (Yq) were described in men with idiopathic azoo- or oligozoospermia and seem to cause impairment of spermatogenesis. Deletion frequencies differ considerably among selected infertile men. The aim of this study was to investigate the prevalence of Yq microdeletions in patients with idiopathic infertility. Men with azoospermia or oligozoospermia resulting from endocrine or obstructive causes or with a constitutional cytogenetic anomaly were excluded. Ninety-seven patients presenting at infertility centers in Leipzig and Zurich were included in the study. Sixty-four (66%) of them were severely oligozoospermic (sperm concentrations < 5 x 10(6)/mL) and 33 (36%) were azoospermic. A sequence-tagged site (STS) PCR strategy was applied for the microdeletion screening. Thirteen STS markers spanning the whole euchromatic region of Yq were used. No Y-chromosomal microdeletion could be detected in these 97 infertile men. This result suggests a much lower Yq deletion frequency than previously thought, even among strictly selected patients with idiopathic azoo- or oligozoospermia.

Adolescent↗
PubMed2001

Recombination hotspot in NF1 microdeletion patients.

Neurofibromatosis type 1 (NF1) patients that are heterozygous for an NF1 microdeletion are remarkable for an early age at onset and an excessive burden of dermal neurofibromas. Microdeletions are predominantly maternal in origin and arise by unequal crossover between misaligned NF1REP paralogous sequence blocks which flank the NF1 gene. We mapped and sequenced the breakpoints in several patients and designed primers within each paralog to specifically amplify a 3.4 kb deletion junction fragment. This assay amplified a deletion junction fragment from 25 of the 54 unrelated NF1 microdeletion patients screened. Sequence analysis demonstrated that each of the 25 recombination events occurred in a discrete 2 kb recombination hotspot within each of the flanking NF1REPs. Two recombination events were accompanied by apparent gene conversion. A search for recombination-prone motifs revealed a chi-like sequence; however, it is unknown whether this element stimulates recombination to occur at the hotspot. The deletion-junction assay will facilitate the prospective identification of patients with NF1 microdeletion at this hotspot for genotype-phenotype correlation studies and diagnostic evaluation.

Alleles↗
PubMed1999

Y chromosome microdeletion in a father and his four infertile sons.

Microdeletions of Yq are associated with azoospermia and severe oligozoospermia. In general, men with deletions are infertile and therefore deletions are not transmitted to sons unless in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are performed. We report an unusual family characterized by multiple members with infertility and Yq microdeletion. Complete reproductive history, semen analyses and blood samples were elicited from relevant family members. DNA preparation and quantification were performed using commercial kits. A total of 27 pairs of sequence tagged sites based primer sets specific for the Y microdeletion region loci were used for screening. Southern blots using deleted in azoospermia (DAZ) and ribosomal binding motif (RBM) cDNAs were then analysed for confirmation. The proband, his three brothers and father were all found to be deleted for DAZ but not RBM. At the time of analysis, the proband's father was azoospermic whereas his four sons were either severely oligozoospermic or azoospermic. Unlike their father, the four sons are infertile and have no offspring, except for one of them who achieved a daughter only after IVF/ICSI treatment for infertility. Microdeletions of Yq involving the DAZ gene are associated with a variable phenotypic expression that can include evidently normal fertility.

Blotting, Southern↗
PubMed1999

Reproductive decisions of men with microdeletions of the Y chromosome: the role of genetic counselling.

Couples dealing with microdeletions of the Y chromosome have to make decisions about their reproductive future. Do they opt for intracytoplasmic sperm injection (ICSI), artificial insemination with donor insemination (AID) or no treatment? We analysed this decision in 28 couples and investigated the role of the counsellor and the counselling process on the final decision of the couple. Ten counsellors from six fertility clinics in The Netherlands and Belgium were interviewed about their genetic counselling of couples dealing with microdeletions. The answers to the questionnaire were converted to 11 dichotomous variables. Of the 1627 tested men in the six centres, 37 (2.3%) had a microdeletion in the AZFc region, a subregion of the AZF region on the Y chromosome important for normal spermatogenesis. The decisions of 28 of them could be analysed. Most couples chose ICSI (79%). The remaining couples chose donor insemination (7%) or refrained from treatment (14%). Several variables, including the counselling procedure, the counsellor and the available treatments in the fertility centre, influenced the decision of the couple. In conclusion, most couples dealing with microdeletions in the AZF region choose ICSI. Several aspects of the process of genetic counselling appear to be related to the final decision.

Adult↗
PubMed1998

An update on chromosome deletion and microdeletion syndromes.

Chromosome deletion and microdeletion syndromes account for an increasing number of clinically recognizable genetic conditions. New deletion syndromes continue to be characterized, and a number of previously described syndromes are being found to be due to chromosomal deletions or microdeletions. Fluorescent in situ hybridization technologies are in wide clinical use to diagnose deletion and microdeletion syndromes, and future uses of these technologies will provide prognostic information for patients and their parents, as the genes responsible for the phenotypic aspects of various deletion syndromes are identified. Future research studies will focus on delineating critical deletion intervals at a molecular level, and identifying candidate genes for the phenotypic features of deletion and microdeletion syndromes, toward the goal of understanding the pathology of the abnormal developmental and physiologic processes involved in each syndrome.

Chromosome Aberrations↗
PubMed1998

Inherited microdeletion in Xp21.3-22.1 involved in non-specific mental retardation.

X-linked mental retardation (XLMR) is a genetically and clinically heterogeneous common disorder. A cumulative frequency of about 1/600 male births was estimated by different authors, including the fragile X syndrome, which affects 1/4000 males. Given this very high cumulative frequency, identification of genes and molecular mechanisms involved in other XLMRs, represents a challenging task of considerable medical importance. In this report we describe clinical and molecular investigations in the family of a mentally retarded boy for whom a microdeletion in Xp21.3-22.1 was detected within the frame of a previously reported systematic search for deletion using STS-PCR screening. Thorough clinical investigation of the sibling showed that two affected brothers exhibit a moderate non-specific mental retardation without any additional neurological impairment, statural growth deficiency or characteristic dysmorphy. Molecular analysis revealed that the microdeletion observed in this family is an inherited defect which cosegregates with mental retardation as an X-linked recessive condition, since both non-deleted boys and transmitting mother are normal. These results and the inherited microdeletion detected within the same region associated with non-specific MR, reported by Raeymaekers et al., suggest that Xp21.3 MR locus is prone to deletions. Therefore, search for microdeletions in the eight families assigned by linkage analysis to this region might allow a better definition of the critical region and an identification of the gene involved in this X-linked mental retardation.

Child↗
PubMed2005

A novel microdeletion syndrome with loss of the MSH2 locus and hereditary non-polyposis colorectal cancer.

Constitutional chromosome deletions can predispose to the development of cancer with the phenotypic characteristics of inherited cancer syndromes, when the deleted region encompasses a tumour suppressor gene. Examples of such conditions are represented by the cytogenetic deletions associated with retinoblastoma, Wilms tumour and familial adenomatous polyposis. So far, no constitutional deletions involving the genes implicated in hereditary non-polyposis colorectal cancer (HNPCC) have been identified. This may be at least partially because of the lack of distinctive phenotypic manifestations in HNPCC. We describe the first case of a constitutional microdeletion associated with HNPCC. Suspicion of a microdeletion was prompted by the association of mental retardation, postnatal growth deficiency, minor congenital anomalies and early onset (37 years) sporadic colon cancer. The patient was found to harbour a microdeletion within chromosome 2p16-p21, including the MSH2 gene. Since there are very few reports of deletions of the 2p16-p21 region, our observation sets the grounds for the definition of a novel multiple congenital anomaly/mental retardation/cancer microdeletion syndrome.

Abnormalities, Multiple↗
PubMed1997

Y chromosome (Yq11) microdeletions in idiopathic azoospermia.

BACKGROUND: Cytogenetic anomalies and molecular deletions of the Y chromosome in idiopathically sterile men suggest that genetic factor(s) controlling spermatogenesis are located in the distal portion of Yq11. We studied Y chromosome microdeletions in the Yq11.23 region in idiopathic azoospermia. METHODS: We studied 25 azoospermic male patients with a cytogenetically normal 46XY karyotype; 13 exhibited Sertoli-cell-only syndrome and 12 exhibited maturation arrest. Microdeletions in the Yq11 region were examined using the PCR technique with 4 pairs of primers from DNA loci in Yq11.23. RESULTS: Microdeletions in Yq11.23 were detected in 4 of the 25 azoospermic men. The most common deletion was of the Y6HP52pr sequence, which was detected in 3 of 13 men with Sertoli-cell-only syndrome but in only 1 of 12 with maturation arrest. CONCLUSION: Detection of microdeletions within the Yq11 sequence is an important clue to the genetic factor(s) underlying azoospermia.

Adult↗
PubMed2005

Y microdeletions in the Istria county, Croatia.

AIM: To establish the frequency of Y chromosome microdeletions in an unselected group of infertile Croatian men. METHODS: An unselected group of 105 patients (male partners of infertile couples), both with idiopathic and non-idiopathic infertility, consecutively referred to the outpatient infertility clinic, gynecology department, General Hospital Pula, Istria County, Croatia, was examined for the presence or absence of Y chromosome microdeletions by polymerase chain reaction analysis. RESULTS: One of the 105 men (0.95%, 95% CI = 0.17-5.2%) was found to have a microdeletion. CONCLUSION: A low frequency of Y chromosome microdeletions was found in the group of unselected infertile Croatian men.

Adult↗
PubMed2000

Diagnostic analysis of the Rubinstein-Taybi syndrome: five cosmids should be used for microdeletion detection and low number of protein truncating mutations.

Rubinstein-Taybi syndrome (RTS) is a malformation syndrome characterised by facial abnormalities, broad thumbs, broad big toes, and mental retardation. In a subset of RTS patients, microdeletions, translocations, and inversions involving chromosome band 16p13.3 can be detected. We have previously shown that disruption of the human CREB binding protein (CREBBP or CBP) gene, either by these gross chromosomal rearrangements or by point mutations, leads to RTS. CBP is a large nuclear protein involved in transcription regulation, chromatin remodelling, and the integration of several different signal transduction pathways. Here we report diagnostic analysis of CBP in 194 RTS patients, divided into several subsets. In one case the mother is also suspect of having RTS. Analyses of the entire CBP gene by the protein truncation test showed 4/37 truncating mutations. Two point mutations, one 11 bp deletion, and one mutation affecting the splicing of the second exon were detected by subsequent sequencing. Screening the CBP gene for larger deletions, by using different cosmid probes in FISH, showed 14/171 microdeletions. Using five cosmid probes that contain the entire gene, we found 8/89 microdeletions of which 4/8 were 5' or interstitial. This last subset of microdeletions would not have been detected using the commonly used 3' probe RT1, showing the necessity of using all five probes.

Amino Acid Sequence↗
PubMed2005

A method for accurate detection of genomic microdeletions using real-time quantitative PCR.

BACKGROUND: Quantitative Polymerase Chain Reaction (qPCR) is a well-established method for quantifying levels of gene expression, but has not been routinely applied to the detection of constitutional copy number alterations of human genomic DNA. Microdeletions or microduplications of the human genome are associated with a variety of genetic disorders. Although, clinical laboratories routinely use fluorescence in situ hybridization (FISH) to identify such cryptic genomic alterations, there remains a significant number of individuals in which constitutional genomic imbalance is suspected, based on clinical parameters, but cannot be readily detected using current cytogenetic techniques. RESULTS: In this study, a novel application for real-time qPCR is presented that can be used to reproducibly detect chromosomal microdeletions and microduplications. This approach was applied to DNA from a series of patient samples and controls to validate genomic copy number alteration at cytoband 22q11. The study group comprised 12 patients with clinical symptoms of chromosome 22q11 deletion syndrome (22q11DS), 1 patient trisomic for 22q11 and 4 normal controls. 6 of the patients (group 1) had known hemizygous deletions, as detected by standard diagnostic FISH, whilst the remaining 6 patients (group 2) were classified as 22q11DS negative using the clinical FISH assay. Screening of the patients and controls with a set of 10 real time qPCR primers, spanning the 22q11.2-deleted region and flanking sequence, confirmed the FISH assay results for all patients with 100% concordance. Moreover, this qPCR enabled a refinement of the region of deletion at 22q11. Analysis of DNA from chromosome 22 trisomic sample demonstrated genomic duplication within 22q11. CONCLUSION: In this paper we present a qPCR approach for the detection of chromosomal microdeletions and microduplications. The strategic use of in silico modelling for qPCR primer design to avoid regions of repetitive DNA, whilst providing a level of genomic resolution greater than standard cytogenetic assays. The implementation of qPCR detection in clinical laboratories will address the need to replace complex, expensive and time consuming FISH screening to detect genomic microdeletions or duplications of clinical importance.

Chromosomes, Human, Pair 22↗
PubMed2001

Y chromosome microdeletions and alterations of spermatogenesis.

Three different spermatogenesis loci have been mapped on the Y chromosome and named "azoospermia factors" (AZFa, b, and c). Deletions in these regions remove one or more of the candidate genes (DAZ, RBMY, USP9Y, and DBY) and cause severe testiculopathy leading to male infertility. We have reviewed the literature and the most recent advances in Y chromosome mapping, focusing our attention on the correlation between Y chromosome microdeletions and alterations of spermatogenesis. More than 4,800 infertile patients were screened for Y microdeletions and published. Such deletions determine azoospermia more frequently than severe oligozoospermia and involve especially the AZFc region including the DAZ gene family. Overall, the prevalence of Y chromosome microdeletions is 4% in oligozoospermic patients, 14% in idiopathic severely oligozoospermic men, 11% in azoospermic men, and 18% in idiopathic azoospermic subjects. Patient selection criteria appear to substantially influence the prevalence of microdeletions. No clear correlation exists between the size and localization of the deletions and the testicular phenotype. However, it is clear that larger deletions are associated with the most severe testicular damage. Patients with Y chromosome deletions frequently have sperm either in the ejaculate or within the testis and are therefore suitable candidates for assisted reproduction techniques. This possibility raises a number of medical and ethical concerns, since the use of spermatozoa carrying Y chromosome deletions may produce pregnancies, but in such cases the genetic anomaly will invariably be passed on to male offspring.

Chromosome Aberrations↗
PubMed2006

Somatic cytogenetic and azoospermia factor gene microdeletion studies in infertile men.

The objective of the present study was to determine the frequency of somatic chromosomal anomalies and Y chromosomal microdeletions (azoospermia factor genes, AZF) in infertile males who seek assisted reproduction. These studies are very important because the assisted reproduction techniques (mainly intracytoplasmic sperm injection) bypass the natural selection process and some classical chromosomal abnormalities, microdeletions of AZF genes or some deleterious genic mutations could pass through generations. These genetic abnormalities can cause in the offspring of these patients male infertility, ambiguous external genitalia, mental retardation, and other birth defects. We studied 165 infertile men whose infertility was attributable to testicular problems (60 were azoospermic, 100 were oligospermic and 5 were asthenospermic). We studied 100 metaphases per patient with GTG banding obtained from temporary lymphocyte culture for chromosomal abnormality detection and performed a genomic DNA analysis using 28 Y chromosome-specific sequence-tagged sites for Y AZF microdeletion detection. Karyotyping revealed somatic anomalies in 16 subjects (16/165 = 9.6%). Of these 16, 12 were in the azoospermic group (12/60 = 20%) and 4 were in the oligospermic group (4/100 = 4%). The most common chromosomal anomaly was Klinefelter syndrome (10/165 = 6%). Microdeletions of AZF genes were detected in 12 subjects (12/160 = 7.5%). The frequencies detected are similar to those described previously. These results show the importance of genetic evaluation of infertile males prior to assisted reproduction. Such evaluation can lead to genetic counseling and, consequently, to primary and secondary prevention of mental retardation and birth defects.

Chromosome Deletion↗
PubMed2000

Microdeletions on the long arm of the Y chromosome and their association with male-factor infertility.

Significant advances in treatment have enabled previously infertile males to achieve fatherhood, when only a few years ago they would have had no chance of biological paternity. In contrast to the overall success of assisted reproduction, the aetiology of male-factor infertility is poorly understood. Recent studies have shown, however, that a significant proportion of men with severe infertility have microdeletions of the Y chromosome. Furthermore, reports have shown that male infants conceived through assisted reproductive techniques have inherited the same Y-chromosome microdeletion as their fathers. It has thus become important to screen men who are at risk of Y-chromosome microdeletions, as this will determine if counselling is needed prior to starting infertility treatment. This review examines the significance and limitations of the current understanding of Y-chromosome microdeletions in male infertility.

Chromosome Deletion↗
PubMed2002

Asynchronous replication of alleles in genomes carrying a microdeletion.

BACKGROUND: While most allelic pairs of DNA replicate synchronously during the S phase of the cell cycle, some genes normally replicate asynchronously, i.e., genes on the X chromosome and imprinted genes. The replication control mechanism is unknown but was shown to be impaired in malignancies and chromosomal trisomies where replication pattern becomes asynchronous. OBJECTIVES: To determine the level of asynchronization in replication timing of cells from patients with microdeleted genomes. METHODS: We applied monocolor fluorescent in situ hybridization with different probes on leukocytes from microdeleted genomes. RESULTS: All samples derived from the microdeleted genomes showed significantly higher levels of an asynchronized pattern compared to normal individuals. CONCLUSIONS: Even a "small" genetic imbalance (microdeletion) can interfere with gene replication and cell cycle progression, as previously shown in full trisomies.

Allelic Imbalance↗
PubMed2003

[Real-time fluorescent PCR for screening AZFc/DAZ microdeletions on the Y chromosome in male infertility patients].

OBJECTIVE: To develop a real-time fluorescent PCR protocol suitable for the routine screening of AZFc/DAZ microdeletions on the Y chromosome in azoospermic and oligozoospermic male infertility patients. METHODS: A set of real-time fluorescent PCR was established. Eighty-seven azoospermic and ligozoospermic patients undergoing ICSI in the IVF center and 30 azoospermic men undergoing testicular biopsy in the clinic of urology surgery were screened for AZFc/DAZ microdeletions of Y chromosome. RESULTS: Eleven cases (9.4%) of AZFc/DAZ microdeletions were found in 117 cases of azoospermic and oligozoospermic patients by screening of realtime fluorescent PCR. Four cases (6.6%) were found in 61 oligozoospermic patients, and 7 cases (12.5%) were found in 56 azoospermic patients. CONCLUSION: The real-time fluorescent PCR protocol presented in this study is an easy and reliable method for detection of AZFc/DAZ microdeletions on the Y chromosome, which yields identical results to those of the multiplex PCR.

Chromosome Deletion↗
PubMed2004

Yq microdeletions--azoospermia factor candidate genes and spermatogenic arrest.

In the last few years considerable progress has been made in the study of sperm physiology and the biology of gamete interaction, furthering our understanding of the pathophysiology of male infertility. With the advent of assisted reproductive technology and intracytoplasmic sperm injection, study of the various factors leading to spermatogenic impairment has become a major focus of scientific research. Understanding the genetic factors that lead to infertility has taken on a certain urgency, as we have learned not only of the transmission to male offspring of spermatogenic impairment, but that these offspring may also be born with a secondary, larger deletion with worsening of phenotype and genital ambiguity. Ten to twenty-five percent of couples encounter difficulty procreating. Microdeletions of the long arm of the Y chromosome are associated with spermatogenic failure and have been used to define three regions on Yq (AZFa, AZFb, and AZFc) that are critical for spermatogenesis. This study was conceived in order to identify the frequency of submicroscopic interstitial deletions in azoospermia factor loci in infertile Indian males. One hundred and seventy five males with nonobstructive oligozoospermia and azoospermia were included in this study. Semen analysis was done in each case to determine the spermatogenic status-normospermic, oligozoospermic (< 20 million sperm/mL), or azoospermic (no sperm in the semen). Detailed medical, clinical, reproductive, and family histories were taken of each patient. Thirty G-banded metaphases were analyzed in each case and polymerase chain reaction microdeletion analysis was done in 133 cytogenetically normal cases. For this genomic, DNA was extracted using peripheral blood. The sequence tagged site primers tested in each case were sY84, sY86 (AZFa); sY113, sY116, sY127, sY134 (AZFb); sY254, sY255 (AZFc). Polymerase chain reaction amplifications found to be negative were repeated at least three times to confirm the deletion of a given marker. The polymerase chain reaction products were analyzed on a 1.8% agarose gel. Eight of the 133 cases showed deletion of at least one of the sequence tagged site markers. Review of the literature has shown that the overall frequency of microdeletions varies from 1% to 55%. In the present study the frequency of microdeletion was 6.01%. Deletions were detected in cases with known and unknown etiology with bilateral severe testiculopathy.

Chromosome Aberrations↗
PubMed2006

[Screening for Y chromosomal microdeletions in AZF region with modified multiplex PCR].

OBJECTIVE: Screening for Y chromosomal microdeletions in azoospermia factor (AZF) region with modified multiplex PCR. METHODS: 160 cases with spermatogenetic failure were recruited in the experimental group, while 90 cases of donors in controls. According to the laboratory guidelines supported by European Academy of Andrology (EAA) and European Molecular Genetics Quality Network (EMQN), Y chromosomal microdeletions in AZFa, b, c regions were screened with multiplex PCR. The primers of sequence targeted sites (STSs) and conditions of PCR were modified. RESULTS: Using modified multiplex PCR, 14 (8.75%) cases with Y chromosomal microdeletions were found in the experimental group, while no case in controls. There were 12 cases in AZFc, 1 case in AZFa + b + c, 1 case in AZFb + c. According to statistics, the difference between two groups was significant (P <0.001). Reaction products could be clearly separated with agarose gel and finished in 1 h. CONCLUSION: Modified multiplex PCR protocols supported by EAA and EMQN proved to be very accurate, sensitive and quick, which could be put into screening practice for Y chromosomal microdeletions in AZF region.

Adult↗