Fluorescence in situ hybridization and molecular studies in infertile men with dysplasia of the fibrous sheath

Objective

To perform fluorescence in situ hybridization (FISH) and molecular analysis in patients with the genetic sperm defect “dysplasia of the fibrous sheath” (DFS).

Design

Retrospective study.

Setting

Regional Referral Center for Male Infertility, Siena, Italy.

Patient(s)

Twelve infertile patients with DFS sperm defects.

Intervention(s)

Family history, lymphocytic karyotype, physical and hormonal assays, semen analysis.

Main Outcome Measure(s)

The DFS sperm phenotype was defined by light, fluorescent, and electron microscopy. Sperm chromosomal constitution was examined by FISH. Gene deletions were tested by polymerase chain reaction.

Result(s)

The genetic sperm defect DFS was determined by transmission and scanning electron microscopy. Immunofluorescence staining of A-kinase anchoring protein 4 (AKAP4) showed a moderate and diffuse signal, revealing a disorganized and incompletely assembled fibrous sheath. In 11 of 12 DFS patients, polymerase chain reaction for detecting the presence of partial sequence of AKAP4/AKAP3 binding regions gave positive results. Fluorescence in situ hybridization was performed in decondensed sperm nuclei with probes for chromosomes 18, X, and Y. The mean disomy frequency of chromosome 18 was in the normal range, whereas the mean disomy frequencies of sex chromosomes and diploidies were twice those of controls.

Conclusion(s)

These results should be considered when DFS sperm are used in assisted reproductive technology, owing to the high risk of transmission of chromosomal unbalance and of DFS sperm defects to male offspring.

Key Words: Spermatozoa, dysplasia of the fibrous sheath (DFS), AKAP3, AKAP4, transmission electron microscopy (TEM), fluorescence in situ hybridization (FISH)