BackgroundThe 22q11.2 deletion syndrome (22q11.2DS) is caused by hemizygous microdeletions on chromosome 22q11.2 with highly variable physical and neuropsychiatric manifestations. We explored the genotype-phenotype relationship in a relatively large 22q11.2DS cohort treated and monitored in our clinic using comprehensive clinical evaluation and detailed molecular characterization of the deletion.MethodsMolecular analyses in 142 subjects with 22q11.2DS features were performed by FISH and MLPA methods. Participants underwent clinical assessment of physical symptoms and structured psychiatric and cognitive evaluation.ResultsDeletions were found in 110 individuals including one with an atypical nested distal deletion which was missed by the FISH test. Most subjects (88.2%) carried the 3Mb typically deleted region and 11.8% carried 4 types of deletions differing in size and location. No statistically significant genotype-phenotype correlations were found between deletion type and clinical data although some differences in hypocalcemia and cardiovascular anomalies were noted.Analysis of the patient with the distal nested deletion suggested a redundancy of genes causing the physical and neuropsychiatric phenotype in 22q11.2DS and indicating that the psychiatric and cognitive trajectories may be governed by different genes.ConclusionsMLPA is a useful and affordable molecular method combining accurate diagnosis and detailed deletion characterization. Variations in deletion type and clinical manifestations impede the detection of significant differences in samples of moderate size, but analysis of individuals with unique deletions may provide insight into the underlying biological mechanisms.Future genotype-phenotype studies should involve large multicenter collaborations employing uniform clinical standards and high-resolution molecular methods.

Background 22q11.2 deletion syndrome (22q11.2DS) is the most common genetic syndrome associated with schizophrenia. The catechol-o-methyltransferase (COMT) gene is located in the obligatory deletion region, and possible associations between COMT variants and neuropsychiatric manifestations in 22q11.2DS have been reported. The purpose of the current study was to evaluate the effect of COMT hemizygosity and molecular haplotypes on gene expression and enzyme activity and its association with psychotic symptoms in 22q11.2DS. Methods Lymphoblast samples were drawn from 53 individuals with 22q11.2DS and 16 typically developing controls. We measured COMT mRNA and protein expression and enzyme activity using standard procedures. The presence of a psychotic disorder and cognitive deficits were also evaluated using structured testing. Results There was a ~50% reduction in COMT mRNA, protein and enzyme activity levels in 22q11.2DS samples. Haplotype analysis revealed clear phenotypic differences between various Val-containing haplotypes on COMT-3′UTR extended mRNA, S-COMT and MB proteins and enzyme activity. The G variant of rs165599, a 3′UTR SNP, was associated with low levels of COMT expression and with the presence of psychosis and lower performance IQ scores in our 22q11.2DS sample. Finally, we demonstrate that the COMT rs74745580 ‘T’ mutation is associated with absent S-COMT expression and very low COMT activity in two 22q11.2DS individuals. Conclusions Our findings confirm a robust effect of COMT hemizygosity on COMT activity and show complex interactions of variants within the COMT gene that influence COMT biology and confound conclusions based on associations with the Val158Met genotype alone.

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The aim of this prospective clinical study was to test auditory function in patients with Laron syndrome, either untreated or treated with insulin-like growth factor I (IGF-I). The study group consisted of 11 patients with Laron syndrome: 5 untreated adults, 5 children and young adults treated with replacement IGF-I starting at bone age <2 years, and 1 adolescent who started replacement therapy at bone age 4.6 years. The auditory evaluation included pure tone and speech audiometry, tympanometry and acoustic reflexes, otoacoustic emissions, loudness dynamics, auditory brain stem responses and a hyperacusis questionnaire. All untreated patients and the patient who started treatment late had various degrees of sensorineural hearing loss and auditory hypersensitivity; acoustic middle ear reflexes were absent in most of them. All treated children had normal hearing and no auditory hypersensitivity; most had recordable middle ear acoustic reflexes. In conclusion, auditory defects seem to be associated with Laron syndrome and may be prevented by starting treatment with IGF-I at an early developmental age.

The use of MPH in children with VCFS appears to be effective and relatively safe. A comprehensive cardiovascular evaluation for children with VCFS before and during stimulant treatment is recommended.

Williams syndrome (WS) is associated with cognitive deficits, special behavioral phenotype, and high rates of psychiatric disorders. The aims of the present study were: (1) To compare the rates of psychiatric disorders and repetitive behaviors in children with WS to children with idiopathic developmental disability (DDs); (2) To longitudinally assess the change in psychiatric disorders during adolescence in WS; (3) To assess retrospectively the effectiveness and safety of methylphenidate (MPH) treatment in WS children with ADHD. The study consisted of a cohort of 38 children and adolescents (age 13.1 ± 5.2 years) with WS and a sample of age-matched DDs (age 15.0 ± 3.1 years). A current follow-up evaluation was conducted after 5.6 ± 1.6 years for 25 subjects (65.8%) of the WS cohort. The rate of most psychiatric disorders was found similar in children with WS and DD controls. Specific phobia, especially from noises, obsessive-compulsive symptoms (e.g., aggressive obsessions and repetitive questions), and stereotypic behaviors (e.g., glancing), were more common in WS than DDs. In a longitudinal follow-up of the WS children, we found a decrease in the rate of anxiety disorders. In addition, a clinically significant improvement was reported in 72.2% of WS children with ADHD following MPH treatment. Sadness/unhappiness was the most common side effect associated with MPH treatment in WS, occurring in 2/3 of treated individuals. The present study further elucidates the neuropsychiatric phenotype of WS. Our results also suggest that MPH treatment for ADHD in WS warrants future prospective controlled trials.

These findings offer a wide perspective on unique versus common phenotypes in 22q11.2DS and WS.