Cytogenetics

With more than thirty years of research experience, the Cytogenetics Department within Toma Advanced Biomedical Assays constitutes one of the most extensive and knowledgeable bodies of scientific research at the international level. To date, 150,000 cases of amniotic fluid samples have been examined in this laboratory; 81,000 analysis on samples of chorionic villi and more than 58,000 on peripheral blood lymphocytes. This astronomical number of examinations has made the laboratory a centre of reference for both public and private institutions across the entire Italy. Furthermore, ever at the forefront of research, Toma Advanced Biomedical Assays was the first cytogenetic laboratory in Italy to carry out analysis on samples originating in every one of the country’s regions, thus enabling conceiving mothers to avoid tiring trips to test centres. Study of the chromosome complement (the karyotype) is carried out following the most advanced national and international protocols, via application of highly sophisticated computerised systems. In order to resolve the most problematic cases, the laboratory can also apply supplementary techniques of molecular cytogenetics.

 


CONVENTIONAL CYTOGENETICS
Cytogenetics is the branch of human genetics that studies the chromosome complement of given individuals (the karyotype) with the aim of identifying the presence of any anomalies that may underline specific pathological conditions or reduced fertility. Chromosomes may be studied both in the prenatal and in the post-natal stages.

  • Karyotype analysis during the prenatal stage is performed on amniotic fluid cells or on those of the chorionic villi. It provides a assured method of ascertaining whether the foetus is affected by alterations to the chromosomal endowment. A cytogenetic examination consists in visualising individual chromosomes by obtaining images of them, which are recorded and analysed by a computer. This enables the highlighting of any chromosomal anomalies, whether in terms of number (such as trisomy or monosomy), or in terms of structure (translocation, deletion, duplication etc.) From the psychological point of view, ruling out any chromosomal anomalies in the foetus’ genetic complement frees the mother from anxiety, enabling her to experience a worry-free pregnancy.
  • During the post-natal stage, karyotype analysis is usually performed on peripheral blood lymphocytes. This enables the identification of chromosomal anomalies associated with specific pathological conditions, of a fall in fertility or of a higher probability of giving birth to children affected by chromosomal pathologies.

 

ANALYSIS (during the prenatal stage)
Karyotype of chorionic villi
Karyotype of amniotic fluid cells
Karyotype of foetal blood
karyotype from abortive tissue
ANALYSIS (during the post-natal stage)
Karyotype of peripheral blood
Karyotype of peripheral blood using high-resolution banding techniques
Karyotype of cutaneous fibroblasts
Karyotype of bone marrow
MENDELIAN SYNDROMES WITH CHROMOSOMAL INSTABILITY
Cytogenetic analysis of Fanconi Anaemia
Cytogenetic analysis of Bloom Syndrome
Cytogenetic analysis of Roberts Syndrome
Cytogenetic analysis of frequency of chromosomal lesions

 


MOLECULAR CYTOGENETICS AND ONCOLOGY
Since the 1990s, a series of methods combining molecular biological techniques with information about the structure of chromosomes have joined forces with conventional cytogenetic analysis, giving rise to molecular cytogenetics.

The purpose of this new molecular discipline is to increase the level of analysis of the karyotype, thus enabling the identification of imbalances in the genome (loss and/or gain of genetic material) that are not visible using conventional cytogenetic techniques. During these years, Toma Advanced Biomedical Assays has not only introduced such analyses into its diagnostic practice, but has contributed, both through validation studies and a series of scientific papers, to developing their transfer to diagnostics. Molecular cytogenetic analyses include targeted methods that aim at investigating specific chromosomal regions, such as FISH and BACs-on-Beads (Bobs) technology. Then there are methods investigating the whole genome at other resolutions – so-called chromosomal microarray analysis.

Regarding the study of the genetic bases of haematological tumours, our laboratory offers the largest range of specific probes using FISH techniques for differential diagnosis of proliferating lymph and myeloid disorders. The ability to recognise specific chromosomal alterations in haematological disorders today offers an indispensable tool in the prognosis of disease and in the choice of therapeutic protocols.

ANALYSIS
fluorescence in-situ hybridization (FISH) using:

  • cosmide probes: subtelomeric, locus specific, onco-haematological;
  • painting probes;
  • alphoid probes;
  • probes for the analysis of subtelomeric rearrangements;
  • BAC clone probes.

Array comparative genomic hybridization (aCGH)
Prenatal BACs on beads (BoBs)
Karyolitic BACs on beads (BoBs)

© 2020 TOMA Advanced Biomedical - Credits