Cytogenetic and molecular study of fifty constitutional rearrangements and fifteen couples with multiple miscarriages using TTAGGG sequence

Telomeres have been extensively studied. In humans, they are constituted of a nonrandom mixture of at least three types of G-rich hexamere repeat units. The majority of telomeric repeat units are detected by the TTAGGG repeat. This sequence is highly conservated and seems to be essential for a normal cellular function. Investigators have studied this sequence in different rearrangements and have raised the intriguing possibility that specific telomere sequences could be involved in cryptic translocations. As telomeric sequences seem to play a primordial role in different rearrangements, we studied the presence of interstitial telomere sequences in 24 patients with a balanced translocation and a normal phenotype and 26 patients with unbalanced rearrangements and an abnormal phenotype. We also tested whether this telomere sequence occured with an increased frequency in couples with multiple miscarriages and without chromosomal abnormality. The data obtained in this study showed no significant telomere interstitial sequence in any patient analyzed as well in balanced and unbalanced rearrangements as in couples with multiple miscarriages. The results obtained from this experiment do not exclude the possibility that interstitial telomere sequences can exist and play a primordial role in cryptic translocations but it seems to be a rare and specific more » event. Presumably, this event may arise when a rearrangement involves several breaks. « less