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Duplications involving the X chromosome, in which the duplicated region is not subject to inactivation, are rare. We describe four distal Xq duplications, in three males and one female, in which the duplicated X chromosomal material is active in all cells. The infantile phenotype bears some resemblance to that of the Prader-Willi syndrome, presenting with initial feeding difficulties, hypotonia and, sometimes, with cryptorchidism. However, the severity of the phenotype is not simply related to the size of the duplication and so variations in gene expression, gene disruption or position effects from breakpoints should be considered as explanations. We have compared the clinical, cytogenetic and molecular findings of our patients with those previously reported. This has enabled us to question the suggestion that duplication of the geneSOX3is the cause of hypopituitarism and that duplication ofFilamin Ais the cause of bilateral periventricular nodular heterotopia/mental retardation syndrome (BPNH/MR). We have also narrowed the putative critical interval forX-linked spina bifida. [ABSTRACT FROM AUTHOR]

A phenotype is emerging for the proximal pair of G-dark bands in 11q (11q14.1 and q14.3) but not yet for the distal pair (11q22.1 and q22.3). A mother and daughter with the same directly transmitted 12.3-Mb interstitial deletion of 11q21q22.3 (GRCh37: 93,551,765-105,817,723) both had initial feeding difficulties and failure to thrive, speech delay, learning difficulties, and mild dysmorphism. Among 17 patients with overlapping deletions, developmental or speech delay, dysmorphism, hypotonia, intellectual disability or learning difficulties, short stature, and coloboma were each found in 2 or more. These results may provide the basis for a consistent phenotype for this region. Among the 53 deleted and additional breakpoint genes, CNTN5, YAP1, and GRI4 were the most likely candidates. Non-penetrance of haploinsufficient genes and dosage compensation among related genes may account for the normal cognition in the mother and variable phenotypes that can extend into the normal range. [ABSTRACT FROM AUTHOR]

Background Microdeletions of 2q23.1 disrupting MBD5 and loss of function mutations of MBD5 cause MBD5-Associated Neurodevelopmental disorders ( MAND). Nearly all reported patients have been isolated cases of de novo origin. Methods This study investigates three families with inherited MBD5 mutations from three different Regional Genetics Centres in the UK. Results Two of the parents in the study had MBD5 deletions in a mosaic form. The parent with an MBD5 deletion in an apparently nonmosaic form has a psychiatric disorder in the absence of developmental delay or dysmorphism. Conclusions Inherited forms of MBD5 deletions are rare, but do occur, especially in a mosaic form. The phenotypic spectrum of MAND may be wider than previously thought. [ABSTRACT FROM AUTHOR]