A normal birth following preimplantation genetic diagnosis by FISH determination in the carriers of der(15)t(Y;15)(Yq12;15p11) translocations: two case reports

Cytogenetic and molecular detection of a rare unbalanced Y;3 translocation in an infertile male: A case report

INTRODUCTION

The infertile male individuals carrying the Y-autosome translocations are seldom reported in clinic. Herein, we described a severe oligozoospermic male with rare unbalanced Y;3 translocation transmitted through 3 generations.

PATIENT CONCERNS

A 33-year-old Chinese male was referred for infertility consultation in our center after 10 years' primary infertility. He was diagnosed as severe oligozoospermia according to the semen analysis.

DIAGNOSIS

G-banding analysis initially described the karyotype as 46, XY, add (3) (p26) for the patient, and his wife's karyotype was 46, XX. The chromosomal microarray analysis identified 3.81Mb and 0.29Mb duplications in Yq11.223q11.23 and Yq12, separately. No deletions were detected in azoospermia factors (AZF)a, AZFb and AZFc. Fluorescence in situ hybridization analysis further confirmed the existence of sex-determining region Y gene and verified that Yq12 was translocated to the terminal short arm of chromosome 3(3p26).

INTERVENTIONS

The couple chose intracytoplasmic sperm injection to get their offspring. The wife underwent amniocentesis for cytogenetic analysis but suffered termination of pregnancy due to premature rupture of membranes.

OUTCOMES

The karyotype of the patient was finally described as 46, X, der(3)t(Y;3)(q11.22;p26). His father and the aborted fetus showed the same karyotypes as the patient.

CONCLUSION

Our study not only enriched the karyotype-phenotype correlation of Y-autosome translocation, but also strengthened the critical roles of molecular genetic techniques in identifying the chromosomal breakpoints and regions involved.

Prenatal diagnosis of the maternal derivative chromosome der(15)t(Y;15)(q12;p13) in a dizygotic twin pregnancy

Sex chromosome translocations are unique and must be considered separately from translocations between autosomes. Here, we describe the first prenatal case of one twin fetus with an unbalanced translocation between chromosome Y and chromosome 15, presenting a 46,XY,der(15)t(Y;15) karyotype. The other twin had a normal 46,XY karyotype. Cytogenetic analysis of the parental chromosomes revealed that the father had a normal 46,XY karyotype, whereas the mother exhibited a 46,XX,der(15) t(Y;15) karyotype. Thus, the proband inherited this translocation from the mother. Fluorescence in situ hybridization analyses demonstrated that the breakpoint on chromosome Y involved a heterochromatin region (Yq12), while that on chromosome 15 involved a p-arm region (15p13). At 37 gestational weeks, healthy twins were delivered vaginally. We conclude that accurate identification of der(15) chromosomal content can facilitate not only prenatal diagnosis of a chromosomal aberration in one twin, but also prediction of the fetal phenotype.

Chromosome aberrations and spermatogenic disorders in mice with Robertsonian translocation (11; 13)

OBJECTIVE

To determine the diagnostic features of Robertsonian (Rob) translocation (11; 13) in mice and the mechanisms underlying the effect on spermatogenesis and reproductive decline.

METHODS

A Rob translocation (11; 13) mouse model was established by cross-breeding, and confirmed by chromosome analysis. Chromosome aberrations and translocation patterns were identified in mice with Rob translocation (11; 13) by fluorescence in situ hybridization (FISH). Spermatogenic disorders were investigated at different stages of spermatogenesis. Immunofluorescent analysis was performed on sections of testis and epididymis specimens during spermatogenic meiosis. The weight of the testes and reproductive decline were recorded.

RESULTS

The crossed Rob translocation (11; 13) mouse has 39 chromosomes, including a fusion chromosome (included chromosomes 11 and 13) using dual color FISH. There was no difference in the distribution pattern of SYCP3 and γH2AX in spermatocytes between Rob translocation and wild-type mice; however, round haploid spermatids presented characteristic morphologic changes of apoptosis and the number of haploid spermatids was decreased. Furthermore, the immature germ cells were released into the epididymis and the number of mature sperm was reduced.

CONCLUSIONS

Chromosome aberrations and spermatogenic disorders may result from apoptosis of round haploid spermatids and a reduced number of mature sperm in Rob translocation (11; 13) mice. Abnormal sperm and reduced number of sperm may be one of the main reasons for reproductive decline and male infertility in Rob translocation (11; 13) mice.

A new multicolor fluorescence in situ hybridization probe set directed against human heterochromatin: HCM-FISH

A new multicolor fluorescence in situ hybridization (mFISH) probe set is presented, and its possible applications are highlighted in 25 clinical cases. The so-called heterochromatin-M-FISH (HCM-FISH) probe set enables a one-step characterization of the large heterochromatic regions within the human genome. HCM-FISH closes a gap in the now available mFISH probe sets, as those do not normally cover the acrocentric short arms; the large pericentric regions of chromosomes 1, 9, and 16; as well as the band Yq12. Still, these regions can be involved in different kinds of chromosomal rearrangements such as translocations, insertions, inversions, amplifications, and marker chromosome formations. Here, examples are given for all these kinds of chromosomal aberrations, detected as constitutional rearrangements in clinical cases. Application perspectives of the probe set in tumors as well as in evolutionary cytogenetic studies are given.