Abstract：
Duplications of the 3q29 cytoband are rare chromosomal copy number variations (CNVs) (overlapping or recurrent ~1.6 Mb 3q29 duplications). They have been associated with highly variable neurodevelopmental disorders (NDDs) with various associated features or reported as a susceptibility factor to the development of learning disabilities and neuropsychiatric disorders. The smallest region of overlap and the phenotype of 3q29 duplications remain uncertain. We here report a French cohort of 31 families with a 3q29 duplication identified by chromosomal microarray analysis (CMA), including 14 recurrent 1.6 Mb duplications, eight overlapping duplications (>1 Mb), and nine small duplications (<1 Mb). Additional genetic findings that may be involved in the phenotype were identified in 11 patients. Focusing on apparently isolated 3q29 duplications, patients present mainly mild NDD as suggested by a high rate of learning disabilities in contrast to a low proportion of patients with intellectual disabilities. Although some are de novo, most of the 3q29 duplications are inherited from a parent with a similar mild phenotype. Besides, the study of small 3q29 duplications does not provide evidence for any critical region. Our data suggest that the overlapping and recurrent 3q29 duplications seem to lead to mild NDD and that a severe or syndromic clinical presentation should warrant further genetic analyses.
摘要：
3q29细胞带的重复是罕见的染色体拷贝数变异（CNV）（重叠或复发〜1.6Mb3q29重复）。它们与具有各种相关特征的高度可变的神经发育障碍（NDD）有关，或被报道为学习障碍和神经精神障碍发展的易感性因素。重叠的最小区域和3q29重复的表型仍然不确定。我们在这里报告了一个由31个家族组成的法国队列，通过染色体微阵列分析（CMA）鉴定出3q29重复，包括14次重复的1.6Mb重复，八个重叠重复(>1Mb)，和9个小重复(<1Mb)。在11例患者中发现了可能与表型有关的其他遗传发现。专注于明显孤立的3q29重复，与较低比例的智障患者相比，高学习障碍率表明患者主要表现为轻度NDD。虽然有些是从头的，大部分的3q29重复遗传自具有相似轻度表型的亲本.此外,小的3q29重复的研究没有提供任何关键区域的证据。我们的数据表明，重叠和复发的3q29重复似乎导致轻度NDD，并且严重或综合征的临床表现应需要进一步的遗传分析。
