RABAT Research team in genomics and molecular epidemiology of genetic diseases, Genomics Center of Human Pathologies, Faculty of Medicine and Pharmacy, University Mohammed V, Rabat, Morocco.
Département de Génétique Médicale, Institut National d'Hygiène, Rabat, Morocco.
Ophthalmic Genet. 2022 Oct;43(5):689-692. doi: 10.1080/13816810.2022.2083183. Epub 2022 Jun 6.
Retinoblastoma (RB) is the most common malignant intraocular tumor in children; it affects their eyes often even prenatally. RB may be sporadic or familial, due to germinal mutation in RB1 gene or by abnormal chromosomal abnormalities involving RB1 gene, located in 13q14. Monosomy of subband 13q14 as a partial deletion can also be responsible for RB with additional symptoms. The latter may be RB associated with psychomotor retardation, macrocephaly, broad forehead, thick earlobes, and bulbous nose.
We present here the case of a boy from a consanguineous marriage with bilateral retinoblastoma, intellectual disability and facial dysmorphic features. Classical and molecular cytogenetics were used to recognize genotype-phenotype association.
The karyotype showed a three way translocation involving chromosomes 5, 12 and 13. Further molecular cytogenetics analysis revealed a deletion of 13q14 involving the tumor suppressor gene RB1.
This case highlights the impact of classical and molecular cytogenetics in diagnosis of rare genetic syndromes and for the genetic counselling of patients and their families. Pure molecular karyotyping analyses would miss the underlying chromosomal mechanism leading to the rearrangement.
视网膜母细胞瘤（RB）是儿童中最常见的恶性眼内肿瘤；它甚至可以在胎儿期就影响他们的眼睛。RB 可能是散发性的或家族性的，这是由于 RB1 基因的种系突变，或由于涉及 RB1 基因的异常染色体异常，该基因位于 13q14。13q14 亚带的单体性作为部分缺失也可能导致 RB 伴有其他症状。后者可能是与精神运动发育迟缓、大头畸形、宽额头、厚耳垂和球状鼻相关的 RB。
我们在这里介绍了一个来自近亲结婚的男孩的病例，他患有双侧视网膜母细胞瘤、智力残疾和面部畸形特征。经典和分子细胞遗传学用于识别基因型-表型相关性。
核型显示涉及染色体 5、12 和 13 的三向易位。进一步的分子细胞遗传学分析显示 13q14 的缺失涉及肿瘤抑制基因 RB1。
该病例强调了经典和分子细胞遗传学在诊断罕见遗传综合征以及为患者及其家属提供遗传咨询方面的作用。纯分子细胞遗传学分析将遗漏导致重排的潜在染色体机制。
