Multiplex sequence-tagged site PCR for efficient screening of microdeletions in Y chromosome in infertile males with azoospermia or severe oligozoospermia

An infertile patient with Y chromosome b1/b3 deletion presenting with congenital bilateral absence of the vas deferens with normal spermatogenesis

We report the case of a 46-year-old Chinese male patient who visited our clinic complaining of infertility. Semen analysis revealed azoospermia, and azoospermia factor c region partial deletion (b1/b3) was detected using Y chromosome microdeletion analysis. Testicular sperm extraction was performed after genetic counseling. The bilateral ductus deferens and a portion of the epididymis were absent, whereas the remaining epididymis was expanded. Motile intratesticular spermatozoa were successfully extracted from the seminiferous tubule. On histopathology, nearly complete spermatogenesis was confirmed in almost every seminiferous tubule. To our knowledge, this is the first case report of b1/b3 deletion with a congenital bilateral absence of the vas deferens and almost normal spermatogenesis.

Molecular analysis of CAG repeat length of the androgen receptor gene and Y chromosome microdeletions among Jordanian azoospermic infertile males

Assisted reproductive technology is a common procedure which helps millions of couples who suffer fertility problems worldwide every year. Screening for genetic abnormalities prior to such procedure is very important to prevent the transmission of harmful genetic mutations to future generations. Microdeletions within the azoospermia factor (AZF) region of the Y chromosome and the expansion of the CAG trinucleotides in the androgen receptor (AR) gene are among the susceptible causes of male infertility in different ethnic groups. Such association has never been studied in Jordan. In this study, we compared CAG repeat length between azoospermic infertile and normospermic fertile Jordanian males and we also screened the frequency of Y chromosome microdeletions in the same cohort. The study included 142 nonobstructive azoospermic cases and 145 normospermic controls. Results have shown that the median CAG repeat length in the azoospermic group is 19 ± 2 compared to 19 ± 1.5 (p = .6262) in the control group. Deletions within the Y chromosome AZF region were detected in 7 of 142 cases (4.93%) and no deletions were seen in the control group. The results of this study confirm the importance of the AZF region in normal spermatogenesis, whereas it shows no link between the length of CAG repeats in the AR gene and male azoospermia in Jordanian group examined.

Copy number variation and microdeletions of the Y chromosome linked genes and loci across different categories of Indian infertile males

We analyzed 34 azoospermic (AZ), 43 oligospermic (OS), and 40 infertile males with normal spermiogram (INS) together with 55 normal fertile males (NFM) from the Indian population. AZ showed more microdeletions in the AZFa and AZFb regions whereas oligospermic ones showed more microdeletions in the AZFc region. Frequency of the AZF partial deletions was higher in males with spermatogenic impairments than in INS. Significantly, SRY, DAZ and BPY2 genes showed copy number variation across different categories of the patients and much reduced copies of the DYZ1 repeat arrays compared to that in normal fertile males. Likewise, INS showed microdeletions, sequence and copy number variation of several Y linked genes and loci. In the context of infertility, STS deletions and copy number variations both were statistically significant (p = 0.001). Thus, semen samples used during in vitro fertilization (IVF) and assisted reproductive technology (ART) must be assessed for the microdeletions of AZFa, b and c regions in addition to the affected genes reported herein. Present study is envisaged to be useful for DNA based diagnosis of different categories of the infertile males lending support to genetic counseling to the couples aspiring to avail assisted reproductive technologies.

Azoospermia factor and male infertility

Recently, work has shown that azoospermia factor (AZF) microdeletions result from homologous recombination between almost identical blocks in this gene region. These microdeletions in the Y chromosome are a common molecular genetic cause of spermatogenetic failure leading to male infertility. After completion of the sequencing of the Y chromosome, the classical definition of AZFa, AZFb, and AZFc was modified to five regions, namely AZFa, P5/proximal-P1, P5/distal-P1, P4/distal-P1, and AZFc, as a result of the determination of Y chromosomal structure. Moreover, partial AZFc deletions have also been reported, resulting from recombination in their sub-ampliconic identical pair sequences. These deletions are also implicated in a possible association with Y chromosome haplogroups. In this review, we address Y chromosomal complexity and the modified categories of the AZF deletions. Recognition of the association of Y deletions with male infertility has implications for the diagnosis, treatment, and genetic counseling of infertile men, in particular candidates for intracytoplasmic sperm injection.

Evaluation of Sperm Chromatin Quality and Screening of Y Chromosome Microdeletions in Greek Males with Severe Oligozoospermia

Normal (n = 20) and abnormal (n = 21) semen samples were explored for possible relationships between conventional semen parameters, chromatin status, and microdeletions in the Y chromosome. DNA fragmentation was detected by the terminal deoxynucleotidyl trasferase-mediated dUTP-nick end labelling (TUNEL) assay, chromatin condensation, and DNA packaging quality were assessed by chromomycin A3 (CMA(3)) staining. All men were investigated for Y chromosome microdeletions using polymerase chain reaction (PCR). No deletions were detected in 21 severely oligozoospermic men for the three screened regions (AZFa, AZFb, and AZFc). Men with normal semen parameters showed better chromatin condensation. Spermatozoa with low motility were more likely to contain loosely packaged chromatin. In the abnormal semen group, DNA fragmentation (TUNEL) correlated significantly with sperm motility, concentration, and chromatin packaging assessed by chromomycin A3. However sperm morphology did not correlate significantly with TUNEL and CMA(3) staining.

Study of azoospermia factor-a deletion caused by homologous recombination between the human endogenous retroviral elements and population-specific alleles in Japanese infertile males

OBJECTIVE

To evaluate the relationship between the status of homologous recombination and population-specific alleles in infertile Japanese males with azoospermia factor (AZF)-a deletions and to characterize the clinical features of these patients.

DESIGN

Retrospective deletion study in infertile Japanese men.

SETTING

University hospital and reproductive clinic.

PATIENT(S)

A total of 931 consecutive patients visiting a male-infertility clinic were genetically evaluated.

INTERVENTION(S)

Patients were analyzed for Y-chromosomal microdeletions and the breakpoints of intrachromosomal homologous recombination of human endogenous retrovirus (HERV) 15qy; in addition, Y-haplogroup typing on the basis of polymerase chain reaction also was performed. Endogenous retroviruses contribute to the evolution of the host genome and can be associated with disease.

MAIN OUTCOME MEASURE(S)

Presence or absence of appropriately sized polymerase chain reaction products.

RESULT(S)

Four cases of AZFa deletions were found. All patients with AZFa deletions had an azoospermia and breakpoints in the ID2 region of HERV15qy. Three of the four cases were derived from Y-haplogroup D2b. Testicular sperm extraction procedures were performed in three of these four patients, and elongated spermatids were recovered in two. However, no pregnancies were successfully achieved.

CONCLUSION(S)

Y-haplotype D2b, specific for some Japanese clade, may be associated with HERV breakpoints that lead to intrachromosomal homologous recombination. From the clinical point of view, the testicular sperm extraction procedure is not applicable to males with complete AZFa deletions.

Clinical consequences of microdeletions of the Y chromosome: the extended Münster experience

A total of 3179 patients were screened for Y-chromosome microdeletions and 821 patients for partial AZFc deletions. Thirty-nine Y-chromosomal microdeletions were found (2.4% of men with <1 x 10(6)/ml spermatozoa): two AZFa, two AZFb, one AZFbc, one partial AZFb, one partial AZFb+c and 32 AZFc (b2/b4). Partial AZFc deletions were found in 45 patients (5.5%), mostly gr/gr deletions (n = 28). In patients with AZFc deletion, azoospermia was found in 53.1% and sperm concentrations of mostly <0.1 x 10(6)/ml were found in 46.9%. Semen analyses and FSH measurements showed no trend over time. Elongated spermatids were seen in 6/15 AZFc patients and bilateral Sertoli cell-only was found in 4/15. Testicular sperm extraction (TESE) was attempted in 10 patients and spermatozoa were found in six. Compared with infertile men matched by sperm concentration, no differences in hormonal and seminal parameters could be found in patients with AZFc or gr/gr deletions. It is concluded that: (i) frequency of AZF deletions in Germany is much lower than in other countries; (ii) AZFc deletions are associated with severe disturbances of spermatogenesis and TESE is not possible in half of these patients; (iii) AZFc and gr/ gr deletions are not associated with any clinical diagnostic parameter; (iv) and no trend is apparent over time.

Frequency of Y chromosome microdeletions and chromosomal abnormalities in infertile Thai men with oligozoospermia and azoospermia

AIM

To investigate the possible causes of oligozoospermia and azoospermia in infertile Thai men, and to find the frequencies of Y chromosome microdeletions and cytogenetic abnormalities in this group.

METHODS

From June 2003 to November 2005, 50 azoospermic and 80 oligozoospermic men were enrolled in the study. A detailed history was taken for each man, followed by general and genital examinations. Y chromosome microdeletions were detected by multiplex polymerase chain reaction (PCR) using 11 gene-specific primers that covered all three regions of the azoospermic factor (AZFa, AZFb and AZFc). Fifty men with normal semen analysis were also studied. Karyotyping was done with the standard G- and Q-banding. Serum concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL) and testosterone were measured by electrochemiluminescence immunoassays (ECLIA).

RESULTS

Azoospermia and oligozoospermia could be explained by previous orchitis in 22.3%, former bilateral cryptorchidism in 19.2%, abnormal karyotypes in 4.6% and Y chromosome microdeletions in 3.8% of the subjects. The most frequent deletions were in the AZFc region (50%), followed by AZFb (33%) and AZFbc (17%). No significant difference was detected in hormonal profiles of infertile men, with or without microdeletions.

CONCLUSION

The frequencies of Y chromosome microdeletions and cytogenetic abnormalities in oligozoospermic and azoospermic Thai men are comparable with similarly infertile men from other Asian and Western countries.

Reevaluation of azoospermic factor c microdeletions using sequence-tagged site markers with confirmed physical positions from the GenBank database

OBJECTIVE

To investigate microdeletions and palindrome complexes in the azoospermic factor (AZF) c regions of the Y chromosome, by polymerase chain reaction (PCR) with sequence-tagged site (STS) markers with known physical positions, after verification of the exact physical locations of candidate STSs and exclusion of those that would give ambiguous results on PCR.

DESIGN

Retrospective STS deletion study in infertile Japanese men.

SETTING

University hospital and reproductive clinic.

PATIENT(S)

A total of 410 men with nonobstructive azoospermia and severe oligospermia (sperm concentrations of <5 x 10(6)/mL).

INTERVENTION(S)

Polymerase chain reaction was performed for all STS markers confirmed to be physically located in the partial AZFb and AZFc regions of the Y chromosome. All STSs were retrieved from the University of California at Santa Cruz database, and their location and specificity were verified.

MAIN OUTCOME MEASURE(S)

Presence or absence of appropriately sized PCR products.

RESULT(S)

Sixty-nine markers were retrieved, 32 of which were not specific to the long arm of the Y chromosome (Yq). The markers retained for test use were contiguous deletions classified as P1+P2 (AZFc) or P3 proximal/P1 (AZFb+c). The prevalence of accurately mapped microdeletions was 5.1% (21 of 410) in this patient population.

CONCLUSION(S)

Although noncontiguous deletions were observed, considerable confusion remained until the genome sequence was finally determined because many of the STSs were either repetitive sequences or polymorphic between individuals or races.

Y chromosome and new concept of azoospermia factor

The completion of a draft sequence of the entire human genome in 2001 was followed by a complete sequencing of the Y chromosome in 2003. It is now possible to refer to a physical map of the Y chromosome. The Y chromosome can be classified into X-transposed, X-degenerate and ampliconic sequences depending on the origins of its sequences. In particular, the ampliconic sequences are complexes of massive palindrome structures in which sequences having higher than 99.9% homology are present symmetrically. Interestingly, palindromic repeats may undergo frequent gene conversion associated with intrachromosomal recombination and play an important role in the maintenance of the genetic materials of the Y chromosome. The azoospermia factor (AZF) region of the ampliconic region is the most probable candidate for spermatogenesis, and forms a palindrome structure. Thus, there is a limit in the detection of microdeletion using conventional sequence-tagged sites based on polymerase chain reaction because of their structure. It is now necessary to update the AZF concept. (Reprod Med Biol 2005; 4: 123-128).