Research Centre for Medical Genetics
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Joint Work of RCMG staff on Characterization of Complex Chromosome Reconstruction in the Patient with PURA Syndrome Was Published

The employees of the cytogenetics laboratory and the consulting department of RCMG described the unique case of complex chromosome reconstruction in the patient with PURA syndrome. The results of the research were published in the journal «Genetics and Molecular Research».

Balanced translocation with the chromosomes 4, 5, 7 was found in the standard cytogenetic examination of the patient with developmental abnormalities. Often the cause of abnormal phenotype in balanced karyotype can be hidden genomic imbalance due to more complex chromosome realignment. To find the causes of the disease the staff of the cytogenetics laboratory used molecular cytogenetic research methods: FISH (targeted serial, non-serial and multicolor DNA probes), chromosome micro-matrix analysis.

The realignment was found to be more complex than originally diagnosed, with more breakpoints and four microdeletions on the chromosomes 4 and 5. One of the microdeletions around 5q31.3 resulted in a clinical picture of PURA syndrome. It is associated with the deletion/mutation of the PURA gene (OMIM #600473). Pathogenic variants in this gene lead to impaired development of the nervous system with infant respiratory failure, hypotonia and feeding problems. To date, 12 patients have been registered (including the presented one) with microdeletions of 5q31.3 and 85 patients with pathogenic variants in the PURA gene.

The cytogenetics of RCMG suggested a mechanism for the formation of complex chromosomal realignment, which led to the genomic imbalance and the appearance of abnormal phenotype in the patient. Non-serial DNA probes were developed on specific chromosomes to clarify the stages of realignment, which helped to confirm this assumption.

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Minzhenkova M.E., Yurchenko D.A., Semenova N.A., Markova Z.G., Tarlycheva A.A., Shilova N.V. (2022). Characterization of a complex chromosomal rearrangement in a girl with PURA syndrome. Genet. Mol. Res. 21(4): GMR19065.