PubMed · 1533300
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R J Gardner. 1992. Nondisjunction versus nonconjunction.. https://pubmed.ncbi.nlm.nih.gov/1533300/
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We present the cytogenetic pattern of a leukemic infant with Diamond-Blackfan anemia (DBA). The karyotype was characterized by clonal evolution involving consecutive gains of chromosome 21 up to pentasomy. No chromosomal changes were present in normal lymphocytes. Such a karyotype evolution has been described in some cases of acute leukemia associated with Down Syndrome, but rarely in non-Down cases.
Cytogenetic heteromorphisms and restriction fragment length polymorphisms were used to assign the parental origins of 30 de novo non-homologous Robertsonian translocations. The balanced and unbalanced translocations studied included 20 rob(14q21q) four rob(13q14q)four rob(15q21q) one rob(13q15q), and one rob(13q21q). Significantly more maternally (26/30) than paternally (4/30) derived de novo translocations were noted and all rob(14q21q) ascertained through unbalanced probands (20/20) were maternal in origin. Interestingly, 12/13 probands who were trisomic and informative for proximal chromosome 21q loci were homozygous for the markers tested. Segregation (2:1) of the Robertsonian translocation into one daughter cell in meiosis I and subsequent failure of the chromosome 21 chromatids to separate in meiosis II may account for our observation of homozygosity for proximal chromosome 21 loci in the majority of de novo rearrangements tested.
Among 50 cases of acute nonlymphocytic leukemia (ANLL) with available cytogenetic data seen in our section since May 1988, two were found to carry a monosomy 21 abnormality which has been rarely reported in hematologic malignancies. The first case is a 58-year-old male with a diagnosis of AML, FAB M2, who died of refractory leukemia 9 months later. The other case is a 59-year-old female with AML, FAB M2. Complete remission was achieved initially but she died of sepsis 3 months later with no evidence of leukemic relapse. Monosomy 21 is not yet recognized as a nonrandom cytogenetic abnormality in ANLL, whereas its unusual predilection in AML, especially the FAB M2 or M4 categories, as noted in our study and others' reports, have raised this possibility. Further studies and the accumulation of new cases are needed in the hope of defining it as a subtype of ANLL.