Syndrome-related chromosome-specific radiation-induced break points of various inherited human metabolic disorders

Genome damage in children with classical Ehlers-Danlos syndrome - An in vivo and in vitro study

Ehlers-Danlos syndrome (EDS) is a heritable connective tissue disorder characterized by skin hyperextensibility, abnormal wound healing, and joint hypermobility with prevalence 1:20 000. Its incidence is probably underestimated due to unknown number of subjects having mild symptoms who may have never been diagnosed through entire life time. Classical EDS is characterized by pathogenic variants of genes encoding type V collagen. The biological effects and health risks of patients with EDS exposure to low doses of ionizing radiation is poorly understood. The aim of this study was to investigate biological effect of low doses of ionizing radiation in children with EDS. Background values of chromosome aberrations in children suffering from classical EDS were determined and compared with control subjects. The in vitro experiment was performed by γ-irradiation of blood lymphocytes from EDS patients and healthy subjects at low doses (0.1, 0.2 and 0.3 Gy). Results show a significant increase level of spontaneous and radiation-induced chromosomal aberrations in children suffering from EDS in comparison with the control subjects (p < 0.05). In conclusion, children with EDS express higher background chromosome aberration frequency and increased radiosensitivity. These findings suggest specific susceptibility of EDS patients and importance of future investigation on risks of diagnostics and therapy which include radiation and genotoxic agents.

Random frequency of radiation induced aberrations in individual chromosomes of lymphocytes of α -thalassemia variant patients

To evaluate the effects of ionizing radiation on chromosomal aberration in lymphocytes of α-thalassemia variants compared to normal controls, venous blood samples were obtained from 10 healthy volunteers and 30 α-thalassemia patients. Different types of α-thalassemia were diagnosed by multiplex polymerase chain reaction. Blood samples were divided into two parts, the first exposed to 3 Gy gamma rays generated from a 60Co source and the other without any irradiation. The blood samples were used for preparation of metaphase cells according to standard methods. Results showed that the frequency of spontaneous aberration (about 0.012 per cell) was similar in all study groups. Irradiated samples showed significantly higher frequency of aberrations (about 0.6 per cell) compared to non-irradiated samples in all groups but similar for control and α-thalassemia variants. The frequency of dicentric chromosomes was significantly higher than other aberrations. In normal individuals in all of the chromosomes except in chromosome 1, a random distribution of break points proportional to their length based on their DNA content was observed. In α-thalassemia variant individuals in all of the chromosomes, a random distribution of break points proportional to their length based on their DNA content was observed.

Frequency of background and radiation-induced apoptosis in leukocytes of individuals with alpha-thalassemia variants, assessed by the neutral comet assay

To study effects of ionizing radiation on apoptosis induction in leukocytes of alpha-thalassemia (alpha-thal) variants compared to normal controls, venous blood samples were obtained from 10 healthy volunteers and 30 alpha-thal patients. Different types alpha-thal were diagnosed by multiplex polymerase chain reaction (PCR). Blood samples were irradiated with three Gy gamma rays, used for comet assay, immediately or 48 h after irradiation. Results show that the frequency of background as well as apoptosis in silent alpha-thal carriers, alpha-thal carriers and controls was similar but there was a significant difference between Hb H patients and other groups in the study. The increased apoptosis in Hb H patients might suggest that accumulation of beta-globin and oxidative stresses are effective in causing apoptosis, and cells from these patients are more vulnerable to damage from radiation-induced toxic substances. Therefore, from alpha-thal patients, those with Hb H disease might be considered as radiosensitive in terms of apoptosis formation.