Interstitial deletions of 6q are associated with variable phenotypes, including growth retardation, dysmorphic features, upper limb malformations, and Prader-Willi (PW)-like features. Only a minority of cases in the literature have been characterized with high resolution techniques, making genotype-phenotype correlations difficult. We report 12 individuals with overlapping, 200-kb to 16.4-Mb interstitial deletions within 6q15q22.33 characterized by microarray-based comparative genomic hybridization to better correlate deletion regions with specific phenotypes. Four individuals have a PW-like phenotype, though only two have deletion of SIM1, the candidate gene for this feature. Therefore, other genes on 6q may contribute to this phenotype including multiple genes on 6q16 and our newly proposed candidate, the transcription cofactor gene VGLL2 on 6q22.2. Two individuals present with movement disorders as a major feature, and ataxia is present in a third. The 4.1-Mb 6q22.1q22.2 critical region for movement disorders includes the cerebellar-expressed candidate gene GOPC. Observed brain malformations include thick corpus callosum in two subjects, cerebellar vermal hypoplasia in two subjects, and cerebellar atrophy in one subject. Seven subjects' deletions overlap a ~250-kb cluster of four genes on 6q22.1 including MARCKS, HDAC2, and HS3ST5, which are involved in neural development. Two subjects have only this gene cluster deleted, and one deletion was apparently de novo, suggesting at least one of these genes plays an important role in development. Although the phenotypes associated with 6q deletions can vary, using overlapping deletions to delineate critical regions improves genotype-phenotype correlation for interstitial 6q deletions.
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We report a case of hepatoblastoma in a 10-year-old girl with mosaic-type trisomy 18. A comprehensive literature review reveals only 2 cases involving mosaic trisomy 18 patients. Our patient underwent an abbreviated chemotherapy course before complete surgical resection. Her hepatoblastoma did not contain cells with trisomy 18. The conservative management approach resulted in a successful outcome; she remains disease free >2 years after surgery. Along with presenting a literature review, this report demonstrates a favorable outcome in a mosaic trisomy 18 child with hepatoblastoma where tumor cells lacked a trisomy 18 karyotype.
NBEA is a candidate gene for autism, and de novo variants have been reported in neurodevelopmental disease (NDD) cohorts. However, NBEA has not been rigorously evaluated as a disease gene, and associated phenotypes have not been delineated. We identified 24 de novo NBEA variants in patients with NDD, establishing NBEA as an NDD gene. Most patients had epilepsy with onset in the first few years of life, often characterized by generalized seizure types, including myoclonic and atonic seizures. Our data show a broader phenotypic spectrum than previously described, including a Myoclonic-Astatic Epilepsy (MAE)-like phenotype in a subset of patients.
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