Paternal isodisomy 7q secondary to monosomy 7 at recurrence in a Down syndrome child with acute myelogenous leukemia.
We report a boy with Down syndrome and leukemia who acquired uniparental isodisomy of chromosome 7q as a secondary chromosomal change during recurrence of the disease. His karyotype before therapy was 46,XY,der(1)t(1;1)(p36;q32),-7,+21c/46,idem,del(9)(p22), whereas at recurrence it was 46,XY,der(1)t(1;1)(p36;q32,-7,der(7)(qter-->p22 through pter::q10-->qter),del(9)(p22),+21c/47,XY,+21c. By using polymerase chain reaction amplification of D7S493 and D7S527 markers, we identified the loss of the maternal chromosome 7 with a consequent paternal isodisomy in the clone with dup7q. This rearrangement could be implicated in the progression of the disease by causing (1) nullisomy for a gene or genes located on 7p22-->pter, (2) functional double doses of exclusively paternal expressed genes, and (3) restoration of the effects produced by haploinsufficiency of biparental expressed genes.
Picos-Cárdenas
V J
VJ
Universidad de Guadalajara and División de Genética, Centro de Investigación Biomédica de Occidente, Centro Médico Nacional de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, Mexico.
Meza-Espinoza
J P
JP
Gutiérrez-Angulo
M
M
Esparza-Flores
M A
MA
Ayala-Madrigal
M L
ML
Hansmann
I
I
González
G J R
GJ
D002675:Child, Preschool; D002871:Chromosome Banding; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics*; D004314:Down Syndrome / Q000150:complications* / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D015470:Leukemia, Myeloid, Acute / Q000150:complications* / Q000235:genetics*; D008297:Male; D011110:Polymorphism, Genetic / Q000235:genetics; D024182:Uniparental Disomy / Q000235:genetics*