A Familial Four-Way Swap Fest

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Science  03 Feb 2006:
Vol. 311, Issue 5761, pp. 579
DOI: 10.1126/science.311.5761.579c

Qualitative advances in technology have made it possible to reexamine an old case, which has led to a heightened appreciation of the fidelity of chromosomal segregation. Over 2 decades ago, a patient with a history of miscarriage was analyzed with classical cytogenetic techniques, yielding evidence of a complex rearrangement involving chromosomes 6, 9, 11, and 20. Later, the mother carried a fetus to term; the adult daughter was determined to carry the same rearrangement and, like the mother, displayed modest levels of the fetal form of hemoglobin [hereditary persistence of fetal hemoglobin (HPFH)].

Fauth et al. have used multiplex fluorescence in situ hybridization and DNA microarrays to map the precise nature of the rearrangements. They find that the derivative chromosome 6 [referred to as der(6)] possessed by mother and daughter contains portions of chromosomes (chrs) 11 and 20, der(11) carries bits of chrs 6 and 9, der(20) contains portions of chrs 6 and 11, and der(9) harbors multiple pieces from chrs 6 and 11, adding up to a total of 12 breakpoints (one of which coincides with a quantitative trait locus for HPFH) spread over four chromosomes. Nevertheless, these rearranged chromosomes pass faithfully through the pachytene stage of meiosis, when homologous chromosomes pair and form bivalents. — GJC

Hum. Genet. 10.1007/s00439-005-0103-z (2006).

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