An atypical 7q11.23 deletion in a normal IQ Williams-Beuren syndrome patient.

Williams-Beuren syndrome (WBS; OMIM no. 194050) is a multisystemic neurodevelopmental disorder caused by a hemizygous deletion of 1.55 Mb on chromosome 7q11.23 spanning 28 genes. Haploinsufficiency of the ELN gene was shown to be responsible for supravalvular aortic stenosis and generalized arteriopathy, whereas LIMK1, CLIP2, GTF2IRD1 and GTF2I genes were suggested to be linked to the specific cognitive profile and craniofacial features. These insights for genotype-phenotype correlations came from the molecular and clinical analysis of patients with atypical deletions and mice models. Here we report a patient showing mild WBS physical phenotype and normal IQ, who carries a shorter 1 Mb atypical deletion. This rearrangement does not include the GTF2IRD1 and GTF2I genes and only partially the BAZ1B gene. Our results are consistent with the hypothesis that hemizygosity of the GTF2IRD1 and GTF2I genes might be involved in the facial dysmorphisms and in the specific motor and cognitive deficits observed in WBS patients.

Perry Syndrome

Disease characteristics. Perry syndrome is characterized by parkinsonism, hypoventilation, depression, and weight loss. The mean age at onset is 48 years; the mean disease duration is five years. Parkinsonism and psychiatric changes (depression, apathy, character changes, and withdrawal) tend to occur early; severe weight loss and hypoventilation manifest later. Diagnosis/testing. The diagnosis is based on clinical findings and molecular genetic testing of DCTN1, the only gene known to be associated with Perry syndrome. Management. Treatment of manifestations: Dopaminergic therapy (particularly levodopa/carbidopa) should be considered in all individuals with significant parkinsonism. Although response to levodopa is often poor, some individuals may have long-term benefit. Noninvasive or invasive ventilation support may improve quality of life and prolong life expectancy. Those patients with psychiatric manifestations may benefit from antidepressants and psychiatric care. Weight loss is managed with appropriate dietary changes. Surveillance: routine evaluation of weight and calorie intake, respiratory function (particularly at night or during sleep), strength; and mood. Agents/circumstances to avoid: Central respiratory depressants (e.g., benzodiazepines, alcohol). Genetic counseling. Perry syndrome is inherited in an autosomal dominant manner. The proportion of cases attributed to de novo mutations is unknown. Each child of an individual with Perry syndrome has a 50% chance of inheriting the mutation. No laboratories offering molecular genetic testing for prenatal diagnosis are listed in the GeneTests Laboratory Directory; however, prenatal testing may be available through laboratories offering custom prenatal testing for families in which the disease-causing mutation has been identified.

Dysregulated ADAM10-Mediated Processing of APP during a Critical Time Window Leads to Synaptic Deficits in Fragile X Syndrome.

The Fragile X mental retardation protein (FMRP) regulates neuronal RNA metabolism, and its absence or mutations leads to the Fragile X syndrome (FXS). The β-amyloid precursor protein (APP) is involved in Alzheimer's disease, plays a role in synapse formation, and is upregulated in intellectual disabilities. Here, we show that during mouse synaptogenesis and in human FXS fibroblasts, a dual dysregulation of APP and the α-secretase ADAM10 leads to the production of an excess of soluble APPα (sAPPα). In FXS, sAPPα signals through the metabotropic receptor that, activating the MAP kinase pathway, leads to synaptic and behavioral deficits. Modulation of ADAM10 activity in FXS reduces sAPPα levels, restoring translational control, synaptic morphology, and behavioral plasticity. Thus, proper control of ADAM10-mediated APP processing during a specific developmental postnatal stage is crucial for healthy spine formation and function(s). Downregulation of ADAM10 activity at synapses may be an effective strategy for ameliorating FXS phenotypes.