Duplication and loss of chromosome 21 in two children with Down Syndrome and acute leukemia
- Pennsylvania State Univ. College of Medicine, Hershey, PA (United States); and others
Acute leukemia in patients with Trisomy 21 (Down Syndrome; DS) may often result in additional karyotypic changes in the number or structure of chromosome 21. We present two DS patients whose immunoblast karyotypes were associated with changes in chromosome 21 ploidy. Patient L.E. developed acute lymphocytic leukemia concomitant with the loss of a single copy of chromosome 21. Trisomy 21 in this individual was due to maternal meiosis I nondisjunction. A recombination event resulted in reduction of maternal alleles to homozygosity distal to D21S167. Loss of the paternal chromosomes in the leukemia clone produced uniparental maternal disomy with isodisomy over a 25cM interval. This could, in theory, permit the unopposed expression of one or more homozygous recessive maternal tumor-associated genes, thus providing an explanation for leukemogenesis in this patient. Patient E.H. was diagnosed with acute monoblastic leukemia and consistently displayed tetrasomy 21 in the blast cell population. The DS karyotype probably arose from a mitotic error in which the paternal chromosome was duplicated. DNA polymorphism analysis indicated that the additional chromosome in the leukemia clone was of maternal origin. The presence of equal numbers of maternal and paternal chromosomes in the tetraploid blast clone would not appear to be consistent with the expression of a mutant tumor suppressor gene in this patient. Although tetrasomy 21 could be a non-specific karyotypic abnormality unrelated to leukemogenesis, it is possible that monoblastic leukemia may be a consequence of increased expression of one or more genes on this chromosome.
- OSTI ID:
- 133566
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0294
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BASIC STUDIES
GENES
GENE RECOMBINATION
GENE MUTATIONS
HUMAN CHROMOSOME 21
GENETIC MAPPING
CHROMOSOMAL ABERRATIONS
NON-DISJUNCTION
PATIENTS
LEUKEMIA
DOWNS SYNDROME
KARYOTYPE
HEREDITARY DISEASES
ANIMAL CELLS
CELL DIVISION
GENETICS
BIOLOGICAL MARKERS
RECESSIVE MUTATIONS
DNA-CLONING