Pisaneschi Elisa, Sirleto Pietro, Lepri Francesca Romana, Genovese Silvia, Dentici Maria Lisa, Petrocchi Stefano, Angioni Adriano, Digilio Maria Cristina, Dallapiccola Bruno
Medical Genetics Laboratory, Bambino Gesù Paediatric Hospital, IRCCS, Rome, Italy.
Bambino Gesù Children Hospital, Molecular Genetics Laboratory, Viale di San Paolo 15, 00146, Rome, Italy.
BMC Med Genet. 2015 Sep 3;16:78. doi: 10.1186/s12881-015-0225-7.
CHARGE syndrome is an autosomal dominant disorder, characterized by ocular Coloboma, congenital Heart defects, choanal Atresia, Retardation, Genital anomalies and Ear anomalies. Over 90 % of typical CHARGE patients are mutated in the CHD7 gene, 65 %-70 % of the cases for all typical and suspected cases combined. The gene encoding for a protein involved in chromatin organization. The mutational spectrum include nonsense, frameshift, splice site, and missense mutations. Large deletions and genomic rearrangements are rare.
We report here on a 5.9 years old male of Moroccan origin displaying classic clinical features of CHARGE syndrome. Using CGH array and NGS analysis we detected a microdeletion (184 kb) involving the promoter region and exon 1 of CHD7 gene and the flanking RAB2 gene.
The present observation suggests that deletion limited to the regulatory region of CHD7 is sufficient to cause the full blown CHARGE phenotype. Different size of deletions can result in different phenotypes, ranging from a milder to severe CHARGE syndrome; this is based on a combination of major and minor diagnostic characteristics, therefore to a more variable clinical features, likely due to the additive effect of other genetic imbalances. MLPA and CGH techniques should be considered in the diagnostic protocol of individuals with a clinical suspect of CHARGE syndrome.
CHARGE综合征是一种常染色体显性疾病,其特征为眼部缺损、先天性心脏缺陷、后鼻孔闭锁、发育迟缓、生殖器畸形和耳部畸形。超过90%的典型CHARGE患者CHD7基因发生突变,所有典型和疑似病例合并计算时,该比例为65%-70%。该基因编码一种参与染色质组织的蛋白质。突变谱包括无义突变、移码突变、剪接位点突变和错义突变。大的缺失和基因组重排很少见。
我们在此报告一名5.9岁的摩洛哥裔男性,表现出CHARGE综合征的典型临床特征。使用比较基因组杂交(CGH)阵列和二代测序(NGS)分析,我们检测到一个184 kb的微缺失,涉及CHD7基因的启动子区域和外显子1以及侧翼的RAB2基因。
目前的观察结果表明,仅限于CHD7调控区域的缺失足以导致典型的CHARGE表型。不同大小的缺失可导致不同的表型,从较轻到严重的CHARGE综合征不等;这是基于主要和次要诊断特征的组合,因此临床特征更具变异性,可能是由于其他基因失衡的累加效应。对于临床怀疑CHARGE综合征的个体,诊断方案中应考虑多重连接探针扩增(MLPA)和CGH技术。