Eggermann T, Rossier E, Theurer-Mainka U, Backsch C, Klein-Vogler U, Enders H, Kaiser P
Abteilung für Klinische Genetik, Institut für Anthropologie und Humangenetik, Universität Tübingen, Germany.
Am J Med Genet. 1998 Feb 17;75(5):530-3.
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.
9号染色体短臂四体是一种罕见的染色体畸变，此前已有28例患者的相关报道。本文报告了一名因发育迟缓、张力亢进、小头畸形、轻微异常及神经代谢异常而前来接受基因评估的新生儿女孩。她的血细胞中有32%存在9号染色体等臂染色体（pter→p10→pter）。羊水细胞中未发现额外的染色体。对取自不同皮肤活检组织的成纤维细胞进行检查，结果显示该组织中也存在嵌合体现象。在取自腹壁的首次活检中，细胞（n = 50）具有正常的染色体组成。对取自左前臂的成纤维细胞进行的进一步分析显示，8个有丝分裂细胞中有5个存在9号染色体等臂染色体。使用9号全染色体探针进行的荧光原位杂交（FISH）证实，额外的标记物起源于9号染色体。分子研究表明，该等臂染色体源自母体。减数分裂不分离之后发生着丝粒错误分裂以及合子后标记物丢失。
