Chromosome 17p13.3 is a gene rich region that when deleted is associated with the well-known Miller-Dieker syndrome. A recently described duplication syndrome involving this region has been associated with intellectual impairment, autism and occasional brain MRI abnormalities. We report 34 additional patients from 21 families to further delineate the clinical, neurological, behavioral, and brain imaging findings. We found a highly diverse phenotype with inter- and intrafamilial variability, especially in cognitive development. The most specific phenotype occurred in individuals with large duplications that include both the YWHAE and LIS1 genes. These patients had a relatively distinct facial phenotype and frequent structural brain abnormalities involving the corpus callosum, cerebellar vermis and cranial base. Autism spectrum disorders were seen in a third of duplication probands, most commonly in those with duplications of YWHAE and flanking genes such as CRK. The typical neurobehavioral phenotype was usually seen in those with the larger duplications. We did not confirm the association of early overgrowth with involvement of YWHAE and CRK, or growth failure with duplications of LIS1. Older patients were often overweight. Three variant phenotypes included cleft lip/palate (CLP), split hand/foot with long bone deficiency (SHFLD), and a connective tissue phenotype resembling Marfan syndrome. The duplications in patients with clefts appear to disrupt ABR, while the SHFLD phenotype was associated with duplication of BHLHA9 as noted in two recent reports. The connective tissue phenotype did not have a convincing critical region. Our experience with this large cohort expands knowledge of this diverse duplication syndrome.

Hereditary spastic paraplegias (HSPs) are characterized by progressive lower extremity spasticity due to an axonal degeneration of motor and sensory neurons. We report a four-generation pedigree segregating an autosomal dominant phenotype for HSP and showing a linkage to the SPG10 locus, coding for Kinesin family member 5A. Subsequent to a denaturing high performance liquid chromatography (dHPLC) mutation screening we found a new missense mutation 838C>T (R280C) at an invariant arginine residue in a region involved in the microtubule binding activity.

Background: To our knowledge, up to now, only 2 mutations in the KIF5A gene, a member of the kinesin superfamily, have been identified as the molecular cause of early-onset autosomal dominant hereditary spastic paraparesis (ADHSP). Objective: To assess the genetic defect in a family with late-onset ADHSP. Patients and Methods: Only the proband agreed to undergo complete neurological testing and mutational analysis. The proband was screened for mutations in the spastin, atlastin, NIPA1, and KIF5A genes, either by denaturing high-performance liquid chromatography or sequence analysis. Results: The history of the family was consistent with ADHSP characterized by late onset of the disease. Mutational analysis results were negative for the spastin, atlastin, and NIPA1 genes but identified a missense mutation (c.1082CϾT) in the coiled-coil coding region of the KIF5A gene. Conclusions: This finding enlarges the phenotypic spectrum of ADHSP linked to KIF5A and enhances the role of that gene in the epidemiology of this disease. We propose that the KIF5A gene should be routinely analyzed in patients with hereditary spastic paraplegia negative for spastin and atlastin mutations.

The 22q11.2 microduplication syndrome is caused by non-allelic homologous recombination mediated by misalignments of low copy repeats located in the region deleted in the DiGeorge syndrome (DGS)/velocardiofacial syndrome (VCFS). The variable phenotype of such condition, consisting in a combination of dysmorphic facial features, cognitive deficits, velopharyngeal insufficiency, congenital heart defects and immunologic derangement, is caused usually in 90% of cases by a 3 Mb deletion or in a minority of cases (7%) by a 1.5 Mb deletion. The most common reciprocal event of deletion is the 3 Mb duplication, reported more recently with a variable phenotype, ranging from multiple defects to normality. In this study, we report a 2.5-year-old girl with cognitive deficits and dysmorphic facial features such as superior placement of eyebrows, upslanting palpebral fissures, widely spaced eyes, broad nasal bridge and epicanthal folds. Fluorescent in situ hybridization for DGS/VCFS region on metaphase chromosomes did not show any apparent anomaly. Subsequent array comparative genomic hybridization study, confirmed by multiplex ligation-dependent probe assay and microsatellite analysis, disclosed a 1.5 Mb de novo 22q11.21 duplication concerning the same chromosomal region deleted in a minority of patients with DGS. These findings identify the minimal duplicated region leading to this emerging syndrome.

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