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Two new cases of analphoid marker chromosomes
Author(s) -
Spiegel Miriam,
Hickmann Gabriele,
Senger Gabriele,
Kozlowski Peter,
Bartsch Oliver
Publication year - 2002
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.10916
Subject(s) - marker chromosome , small supernumerary marker chromosome , biology , tetrasomy , fluorescence in situ hybridization , microdissection , genetics , trisomy , chromosome , chromosome 9 , aneuploidy , karyotype , chromosome 15 , chromosome 21 , chromosomal inversion , gene
Supernumerary marker chromosomes (SMCs) without detectable alphoid DNA represent a rare and interesting class of rearranged marker chromosomes. These SMCs are predicted to have a neocentromere and have been referred to as neocentric marker chromosomes (NMCs). We report the molecular cytogenetic characterization of two new cases of neocentromere‐containing chromosomes, one on 1q43∼44 and one on 15q26. Both cases were examined using fluorescence in situ hybridization (FISH) with various alpha‐satellite DNA probes, and no alphoid DNA was detected. In case 1, the NMC originated from the distal long arm of chromosome 1 by chromosomal microdissection and reverse painting. This marker lacked detectable chromosome 1q subtelomeric sequences, and therefore appeared to be a small ring chromosome. After genetic counseling with a high risk for a MCA/MR syndrome (trisomy 1q43 → q44), the family continued the pregnancy. At age 6 months, the infant demonstrated no congenital or developmental anomalies. This is the first published example of a NMC derived from chromosome 1q. The marker may be one of the smallest, if not the smallest, human NMC reported to date. In case 2, fetal ultrasonography indicated a complex heart defect (abnormal return of lower vena cava, atrial septum malformation) and bilateral hydronephrosis. Molecular cytogenetic analysis showed an inverted duplication of the distal long arm of chromosome 15 (tetrasomy 15q24 → qter). The pregnancy was terminated. Autopsy demonstrated polycystic left kidney and dysplastic right kidney. Case 2 represents the ninth report of a neocentromere on distal chromosome 15q, suggesting that this region may possibly especially support the formation of neocentromeres. © 2002 Wiley‐Liss, Inc.