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ILM – Molecular cytogenetic diagnostics

The ILM used multicolour fluorescence in-situ hybridisation for the detection of chromosomal changes in the vein tissue of patients suffering from recurrent varicosis.

Fig. 1: M-(24 colour)-FISH: Karyogram of a varix cell: 43, XX, t(4;15;5), t(8;12), -9,-11,-22 © ILM

Varicose veins are a common condition with frequent recurrences despite the correct surgical removal of the affected veins. About 50% of patients have a family history of varicose veins, but little is known about the pathophysiological correlation. Looking at cytogenetic alterations is an established method for analysing inheritable diseases. However, only a few investigations have focused on familial varicosis despite its frequency and relevance to healthcare costs. The ILM therefore chose to investigate chromosomal changes in cells of varicose tissue of patients with recurrent varicose veins, using multicolour fluorescence in-situ hybridisation (M-FISH, 24-colour FISH) for the first time ever.

In cooperation with Prof. Dr. Ralf U. Peter from the Vascular and Skin Centre in Blaustein, Germany, primary cell cultures were established from varicose tissue samples. Following the preparation of the chromosomes, the samples were first analysed with M-FISH hybridisation involving DNA probes, then under the fluorescence microscope and finally with specific software. M-FISH enables the exact determination of all human chromosomes and is a very sensitive method for the detection of chromosomal changes. Structural aberrations and alterations in the number of chromosomes (aneusomies) were found in over 50 per cent of the patients investigated. The figure on the left (M-FISH analysis of varicose cells of a female patient) shows chromosomal translocations that can be detected by colour changes (arrows).

Fig. 2: Nucleus with trisomy 7 (© ILM) © ILM

The varicose cells of a male patient were also investigated and changes in the number of chromosomes, particularly in the form of elevated numbers of chromosome 7, were detected. It was later possible to confirm this clonal trisomy 7 on interphase nuclei using FISH and centromere probes for chromosome 7 (Fig. 2). This was the first ever use of M-FISH to detect chromosomal changes and aneusomies in the cells of varicose vein biopsies. There is evidence that structural chromosome aberrations are present in the varicose tissue of patients with a family history of varicosis, but that these aberrations are not present in sporadically occurring cases. Therefore, it is envisaged that our results will be useful in helping to clarify the genetic basis of varicose veins. In addition, studies on varicosis patients and potentially also their relatives could be useful in identifying patients with a higher risk of recurrence so that preventive and therapeutic measures can be initiated in good time.

Website address: https://www.gesundheitsindustrie-bw.de/en/article/press-release/ilm-molecular-cytogenetic-diagnostics