[Genetic analysis of a pedigree with MECP duplication syndrome]

To explore the genetic etiology of a pedigree with mental retardation and hypotonia by using chromosome microarray analysis (CMA), low coverage massive parallel copy number variation sequencing (CNV-seq) and quantitative PCR (qPCR).

Genomic DNA was extracted from peripheral blood samples from two male patients and healthy members from the pedigree. CNV-seq was carried out for one patient. Suspected CNV was verified by qPCR. CNV-seq or single nucleotide polymorphism array (SNP array) were carried out for another patient and his family members.

Both patients showed severe hypotonia and global development delay, in particular language delay. CNV-seq and SNP array indicated that both patients had carried a Xq28 duplication, with spanned 0.26 Mb and 0.42 Mb, respectively. Both duplications encompassed the MECP2 gene. CNV-seq analysis of their family members confirmed that the mother and one sister had carried similar duplications, while an elder brother was normal.

CNV-seq and CMA are rapid and effective tools for the diagnosis of MECP2 duplication syndrome in children with mental retardation, hypotonia and recurrent infections.