New case of mosaic tetrasomy 9p with additional neurometabolic findings.
Tetrasomy 9p is a rare chromosomal aberration that was described in 28 previous patients. Here we report on a newborn girl who was referred for genetic evaluation because of developmental delay, hypertonicity, microcephaly, minor anomalies, and neurometabolic findings. She had an isochromosome 9p (pter --> p10 --> pter) in 32% of blood cells. The extra chromosome was not found in amniocytes. Examination of fibroblasts from different skin biopsies also showed mosaicism in this tissue. In a first biopsy from the abdominal wall, the cells (n = 50) had a normal chromosomal complement. Further analysis of fibroblasts from the left forearm showed the isochromosome 9p in 5 out of 8 mitoses. Fluorescence in situ hybridization (FISH), using a whole chromosome 9 probe, confirmed that the extra marker was 9 in origin. Molecular studies showed that the isochromosome was of maternal origin. Meiotic nondisjunction was followed by centromeric misdivision and postzygotic loss of the marker.
Eggermann
T
T
Abteilung für Klinische Genetik, Institut für Anthropologie und Humangenetik, Universität Tübingen, Germany. kteggermann@uni-tuebingen.de
Rossier
E
E
Theurer-Mainka
U
U
Backsch
C
C
Klein-Vogler
U
U
Enders
H
H
Kaiser
P
P
D002503:Centromere / Q000235:genetics / Q000473:pathology; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics*; D005260:Female; D006801:Humans; D007223:Infant; D018404:Isochromosomes; D007621:Karyotyping; D008540:Meiosis / Q000235:genetics; D009030:Mosaicism / Q000235:genetics* / Q000473:pathology; D011296:Prenatal Diagnosis