Study question: Can the proportion of unbalanced spermatozoa in chromosomal rearrangement carriers be decreased through the use of discontinuous gradient centrifugation (DGC)?
Summary answer: DGC significantly decreases the proportion of genetically unbalanced spermatozoa in chromosomal rearrangement carriers.
What is known already: Chromosomal rearrangement carriers present with a certain proportion of unbalanced gametes, which can lead to miscarriages or malformations in the offspring. There is presently no known way to select the balanced spermatozoa and use them for IVF.
Study design, size, duration: The proportion of unbalanced spermatozoa after DGC was compared with that before DGC in 21 patients with a chromosomal rearrangement. At least 500 spermatozoa were analysed per observation.
Participants/materials, setting, methods: Twenty-one male patients with a chromosomal rearrangement were included in this prospective study. They initially consulted for infertility, recurrent miscarriages or a history of abnormal pregnancy. The samples were split into two, with one part undergoing DGC and the other being immediately fixed. Fluorescence in situ hybridization was performed to establish the chromosome segregation pattern of each spermatozoon.
Main results and the role of chance: DGC significantly decreased the proportion of unbalanced spermatozoa in all but 1 of the 21 chromosomal rearrangement carriers (P < 0.05).
Limitations, reasons for caution: Although DGC reduces the proportion of unbalanced spermatozoa in ejaculates from patients with chromosome rearrangements this elimination is only partial and some abnormal spermatozoa remain. Means to exclude these spermatozoa to ensure that only balanced ones are used in IVF remain to be discovered. The motility and morphology of the sperm before and after DGC were not measured.
Wider implications of the findings: Used in IVF or intrauterine insemination, DGC could decrease the chance that a man carrying a chromosomal rearrangement will father an abnormal fetus.
Keywords: chromosome rearrangements; density gradient centrifugation; spermatozoa; translocation.