Balci S, Aypar E, Beksaç M S, Bartsch O
Department of Clinical Genetics, Hacettepe University Ihsan Dogramaci Children's Hospital, Ankara, Turkey.
Genet Couns. 2009;20(2):125-32.
A severely mentally and motor retarded girl with monosomy 3pter--p25 and trisomy 8q24-qter due to a familial reciprocal translocation t(3;8) (p25;q24): We report a familial translocation t(3;8) in a three generation family that includes a severely retarded 9-year-old girl with intrauterine and postnatal growth retardation, microcephaly, capillary hemangiomas of the forehead and perioral region, synophrys, ptosis, long philtrum, high arched palate, micrognathia, malformed ears, clinodactyly, hypotonia, mental and motor retardation. The pedigree was highly suggestive ofa familial rearrangement. Cytogenetics and fluorescent in situ hybridization (FISH) showed an unbalanced translocation of chromosomes 3p25 and 8q24 of maternal origin, karyotype 46,XX,der(3)t(3;8)(p25q24)mat. Using FISH the breakpoint at 8q24 was located distal of TRPS1, the gene for trichorhinophalangeal syndrome. The balanced translocation was found in the mother, maternal grandmother and prenatally diagnosed brother. Ten individuals (seven miscarriages, niece, two nephews) probably also had an unbalanced translocation. Genetic counseling was given to the family. Because of the hemizygous deletion of the VHL gene at chromosome 3p25.3, the patient is at risk for von Hippel-Lindau (VHL) syndrome, predisposing to retinal, cerebellar, spinal haemangioblastomas, renal cell carcinoma, phaeochromocytoma and pancreatic tumors. Therefore, for early detection and treatment of VHL syndrome, we performed periodic screening beginning at age 5 years. A familial translocation t(3;8) is very rare and there are no previous reports on terminal monosomy 3p (pter-->p25) and terminal trisomy 8q (q24-->qter).
一名患有3pter--p25单体和8q24-qter三体的严重智力和运动发育迟缓女孩,病因是家族性相互易位t(3;8)(p25;q24):我们报告了一个三代家族中的家族性易位t(3;8),该家族中有一名9岁的严重发育迟缓女孩,存在宫内和出生后生长迟缓、小头畸形、前额和口周区域的毛细血管瘤、连眉、上睑下垂、人中长、高拱腭、小颌畸形、耳部畸形、手指弯曲、肌张力低下、智力和运动发育迟缓。家系图谱强烈提示存在家族性重排。细胞遗传学和荧光原位杂交(FISH)显示,源自母亲的3号染色体p25和8号染色体q24发生了不平衡易位,核型为46,XX,der(3)t(3;8)(p25q24)mat。使用FISH技术,8q24处的断点位于毛发鼻指综合征基因TRPS1的远端。在母亲、外祖母和产前诊断的哥哥中发现了平衡易位。另外10个人(7次流产、侄女、2个侄子)可能也存在不平衡易位。已为该家族提供了遗传咨询。由于3号染色体p25.3处的VHL基因半合子缺失,该患者有患冯·希佩尔-林道(VHL)综合征的风险,易患视网膜、小脑、脊髓血管母细胞瘤、肾细胞癌、嗜铬细胞瘤和胰腺肿瘤。因此,为了早期发现和治疗VHL综合征,我们从5岁开始进行定期筛查。家族性易位t(3;8)非常罕见,此前尚无关于3号染色体末端单体(pter-->p25)和8号染色体末端三体(q24-->qter)的报道。