Mosaic isodicentric chromosome 9 with triplication (9p22-pter) and no deletion in an abnormal infant presenting with clinical features of trisomy 9; a new type of isodicentric chromosome formation
- St. Louis Univ., MO (United States)
All human isodicentric chromosomes reported thus far have shown partial or complete deletion of either the short or the long arm of the chromosome. We report a patient who had a complete isodicentric chromosome 9, in which the two long and two short arms have no deletion, but have triplication of the band p22 to pterminal. This abnormality was detected at 10% mosaicism in the blood of an infant with multiple congenital anomalies and clinical features of mosaic trisomy 9. The remaining 90% of metaphases showed one normal 9 and one abnormal monocentric 9 with an inversion triplication of the band 9p22 to 9pterminal. Fluorescent in situ hybridization (FISH) using chromosome 9 painting probe (Imagnetics), and all human telomere probe (Oncor) confirmed the nature of these two abnormal 9`s, which were found in two different cell lines. FISH revealed the presence of short arm interstitial telomeric sequences that defined the borders of the extra copy of 9p22-pter. Error of replication, ligation and crossing-over within the 4 sister chromatids of chromosome 9 is the most likely explanation for the formation of this rare type of isodicentric chromosome. Parental blood chromosomes were normal. Skin fibroblast obtained post mortem failed to grow. Therefore, we can not exclude the possibility that a higher than 10% level of mosaicism of the isodicentric 9 could explain the severe clinical presentation of this patient.
- OSTI ID:
- 133645
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0375
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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