A stable acentric marker chromosome: possible existence of an intercalary ancient centromere at distal 8p.
A centromere is considered to be an essential chromosomal component where microtubule-kinetochore interaction occurs to segregate sister chromatids faithfully and acentric chromosomes are unstable and lost through cell divisions. We report a novel marker chromosome that was acentric but stable through cell divisions. The patient was a 2-year-old girl with mental retardation, patent ductus arteriosus, and mild dysmorphic features. G-banded chromosome analysis revealed that an additional small marker chromosome was observed in all 100 cells examined. By the reverse-chromosome-painting method, the marker was found to originate from the distal region of 8p, and a subsequent two-color FISH analysis with cosmid probes around the region revealed that the marker was an inverted duplication interpreted as 8pter-->p23.1::p23.1-->8pter. No centromeric region was involved in the marker. By FISH, no alpha-satellite sequence was detected on the marker, while a telomere sequence was detected at each end. Anti-kinetochore immunostaining, using a serum from a patient with CREST (calcinosis, Raynaud syndrome, esophageal dismotility, sclerodactyly, and telangiectasia) syndrome, showed a pair of signals on the marker, which indicated that a functional kinetochore was present on the marker. The analysis of this patient might suggest the possibility that an ancient centromere sequence exists at distal 8p (8p23.1-pter) and was activated through the chromosome rearrangement in the patient.
Division of Medical Genetics, Saitama Children's Medical Center, Iwatsuki, Japan.
H
H
Ohashi
K
K
Wakui
K
K
Ogawa
T
T
Okano
N
N
Niikawa
Y
Y
Fukushima
D000015:Abnormalities, Multiple / Q000235:genetics; D017675:CREST Syndrome / Q000276:immunology; D002503:Centromere / Q000737:chemistry / Q000235:genetics*; D002675:Child, Preschool; D002869:Chromosome Aberrations / Q000235:genetics*; D002871:Chromosome Banding; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics* / Q000648:ultrastructure; D004374:Ductus Arteriosus, Patent / Q000235:genetics; D005260:Female; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018386:Kinetochores / Q000737:chemistry / Q000276:immunology; D009687:Nuclear Proteins / Q000737:chemistry / Q000276:immunology; D016133:Polymerase Chain Reaction
D005819:Genetic Markers; D009687:Nuclear Proteins