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Meiotic prophase I defects in an oligospermic man with Wolf-Hirschhorn syndrome with ring chromosome 4

Qi Yao1, Liu Wang2, Bing Yao1

  • 1Institute of Reproductive Medicine, Jinling Hospital, Nanjing University School of Medicine, 305 East Zhongshan Road, Nanjing 210002, PR China.

Molecular Cytogenetics
|July 25, 2014
PubMed
Abstract

Insights

Ring chromosome 4 with 4p16.3 microdeletion impairs male fertility by affecting meiosis. This study reveals how ring chromosomes disrupt spermatogenesis and impact male reproductive health.

Area of Science:

  • Genetics
  • Reproductive Biology
  • Cytogenetics

Background:

  • Ring chromosomes are linked to spermatogenetic failure, but underlying mechanisms remain unclear.
  • This study investigates a patient with severe oligospermia and a ring chromosome 4 (r(4)) with a 4p16.3 microdeletion.

Observation:

  • Meiosis in the patient's testicular biopsy was analyzed using fluorescence immunostaining for synapsis (SCP3), recombination (MLH1), and transcriptional inactivation (BRCA1).
  • The patient exhibited a higher percentage of spermatocytes in the zygotene phase (35.4%) compared to controls (5.2%).
  • Chromosome 4 in pachytene cells showed loop formation and unpaired regions, with BRCA1 localizing to asynapsed areas.

Findings:

  • The patient displayed significantly reduced recombination frequency (45.9 MLH1 foci/cell) versus controls (47.8 MLH1 foci/cell).
  • Ring chromosome 4 appears to disrupt synapsis and recombination during meiosis I prophase.

Implications:

  • Ring chromosome 4 may impede male fertility by affecting meiotic progression, synapse formation, and transcriptional regulation of asynapsed regions.
  • Understanding these mechanisms is crucial for diagnosing and potentially treating male infertility associated with ring chromosomes.
Keywords:
OligospermiaRecombinationRing chromosome 4Synapse complexTranscriptional inactivation

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