Uniparental isodisomy for paternal 7p and maternal 7q in a child with growth retardation

• Published in: American journal of human genetics Vol. 55; no. 2; pp. 253 - 265
• Main Authors: EGGERDING, F. A, SCHONBERG, S. A, CHEHAB, F. F, NORTON, M. E, COX, V. A, EPSTEIN, C. J
• Format: Journal Article
• Language: English
• Published: Chicago, IL University of Chicago Press 01.08.1994
• Subjects: ANIMAL GROWTH; Base Sequence; BASIC BIOLOGICAL SCIENCES; Biological and medical sciences; CHROMOSOMAL ABERRATIONS; chromosome 6; chromosome 7; Chromosome Aberrations; Chromosome Banding; Chromosome Disorders; CHROMOSOMES; Chromosomes, Human, Pair 7; DNA Primers; DNA, Satellite - genetics; Dwarfism - genetics; Fathers; Female; GROWTH; growth retardation; Haplotypes; Homozygote; HUMAN CHROMOSOME 7; HUMAN CHROMOSOMES; Humans; Infant, Newborn; INHIBITION; man; Medical genetics; Medical sciences; Mitosis; Molecular Sequence Data; Mothers; MUTATIONS 550400 > Genetics; Polymorphism, Restriction Fragment Length; uniparental disomy; uniparental isodisomy; Chromosomal aberration; Human; Maternal origin; Infant; Uniparental isodisomy; Isochromosome; Growth retardation; Paternal origin; Phenotype; Abnormal chromosome; Female; Molecular biology; Abnormal C7 chromosome
• ISSN: 0002-9297; 1537-6605

Uniparental isodisomy resulting from the simultaneous presence of isochromosomes of the p and q arms of a chromosome and absence of a normal homologue is an exceptionally rare event. We have observed a growth-retarded female infant in whom the normal chromosome 7 homologues were replaced by what appeared cytogenetically to be isochromosomes of 7p and 7q. Polymorphic microsatellite loci spanning the length of 7p and 7q were analyzed in the proband and her parents to ascertain the parental origin and extent of heterozygosity of the proband's rearranged chromosomes. These studies demonstrated that the 7p alleles of the proband were derived only from the father, the 7q alleles were derived only from the mother, and there was homozygosity for all chromosome 7 loci analyzed. The mechanisms leading to the formation of the proband's isochromosomes could reflect abnormalities of cell division occurring at meiosis, postfertilization mitosis, or both. We believe that the present case may result from incomplete mitotic interchange in the pericentromeric regions of chromosome 7 homologues, with resolution by sister-chromatid reunion in an early, if not first, zygotic division. Phenotypically, our proband resembled three previously reported cases of maternal isodisomy for chromosome 7, suggesting that lack of paternal genes from 7q may result in a phenotype of short stature and growth retardation.