Fragile sites in autosomes: Interchromosomal distribution in patients before ICSI-treatment and their possible influence on the success of the therapy
Investigations were carried out in 904 couples and 51 single patients with proven male infertility before ICSI-treatment.
Within the investigation group the frequency of constitutional chromosome aberrations was 2.4% and the percentage of low gonosomal mosaicism was 6.4%. Autosomal fragile sites were documented in 70 patients (3,8%), with an equal incidence in males and females. Surprisingly, the most frequent fragile site was 6q13 (90%) followed by 10q25 (4.2%), then 16q22 and 17p12 both 2.9%. In 0.4% of the patients (or 10% of probands with fragile sites in autosomes) either both chromosomes 6 were involved or the proband was heterozygous for 2 different fragile sites. The distribution of fragile sites was compared to other cytogenetic parameters investigated. There was no positive correlation between fragile sites and constitutional aberrations (numerical or structural) and low gonosomal mosaicism, or frequent polymorphisms of the heterochromatin such as the pericentric inversion 9 inv(9)(p11q13) or enlargement of the short arms of acrocentrics such as 22p13 s or m i(5).
Furthermore, the following gynecological parameters were documented in couples with fragile sites and compared to a matched control group: Number of fertilisations, embryo transfer, pregnancies, abortions and live-born children.
All parameters were in the same order in the carriers of fragile sites compared to the controls, independent of their sex. However, it has to be taken into account that the number of cases investigated is still small.