Distribution of X-ray-induced chromosome breakpoints in Down syndrome lymphocytes

Journal Article · Mon Jan 01 00:00:00 EST 1990 · American Journal of Medical Genetics, Suppl.; (USA)

DOI:https://doi.org/10.1002/ajmg.1320370740· OSTI ID:5868724

Shafik, H M; Au, W W; Whorton, Jr, E B; Legator, M S ^[1]

---

1. Univ. of Texas Medical Branch, Galveston (USA)

Down syndrome (DS) individuals are known to be predisposed to develop leukemia and their lymphocytes are highly sensitive to the induction of chromosome aberrations by X-rays. A study was conducted to identify the chromosome breakpoints and to evaluate whether site specificity for chromosome breakage and rearrangement may exist which may explain the predisposition phenomenon. DS lymphocytes at the G1 phase of the cell cycle were irradiated with 300, 450, and 600 rad of X-rays. Cells were harvested after 3 days in culture and 193 G-banded karyotypes were analyzed to identify the induced chromosome abnormalities. Out of 273 breakpoints identified, 122 were involved in the formation of stable chromosome rearrangements and 151 in the formation of unstable abnormalities. The Poisson analysis of these breakpoints demonstrated that 16 chromosome bands located in chromosomes 1, 3, 7, 12, 17, 19 and X were preferentially involved in breakage and rearrangement (P less than 0.05). These 16 bands are also found to be locations of cancer breakpoints, oncogenes, or fragile sites. Many abnormal cells were observed to carry stable chromosome rearrangements only. Therefore, these cells are presumed to be compatible with survival and to be initiated in the transformation process. We propose that similar stable and site-specific chromosome rearrangements may exist in proliferating cells in DS individuals after exposure to clastogens and that this abnormality predisposes them to develop leukemia.

• OSTI ID: 5868724
• Journal Information: American Journal of Medical Genetics, Suppl.; (USA), Vol. 7; ISSN 1040-3787
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CHROMOSOMAL ABERRATIONS
RADIOINDUCTION
LYMPHOCYTES
GENETIC RADIATION EFFECTS
CELL CYCLE
DOWNS SYNDROME
KARYOTYPE
LEUKEMIA
ONCOGENES
X RADIATION
ANIMAL CELLS
BIOLOGICAL EFFECTS
BIOLOGICAL MATERIALS
BIOLOGICAL RADIATION EFFECTS
BLOOD
BLOOD CELLS
BODY FLUIDS
CONGENITAL MALFORMATIONS
CONNECTIVE TISSUE CELLS
DISEASES
ELECTROMAGNETIC RADIATION
GENES
GENETIC EFFECTS
HEMIC DISEASES
HEREDITARY DISEASES
IMMUNE SYSTEM DISEASES
IONIZING RADIATIONS
LEUKOCYTES
MALFORMATIONS
MATERIALS
MUTATIONS
NEOPLASMS
PATHOLOGICAL CHANGES
RADIATION EFFECTS
RADIATIONS
SOMATIC CELLS
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture