Microarray Analysis in Syndromic Obesity

Study Overview
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Brief Summary
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Comparative genomic hybridization (CGH) array technology has been used in numerous studies on mental retardation, and few chromosomal abnormalities have been identified in patients. Because chromosomal abnormalities have still been associated with obesity, we can expect that syndromic obesity is also associated with small deletions/duplications. Characterization of deleted or duplicated loci in these obese patients would mean that these loci include genes implicated in obesity. This will permit to propose new gene(s) involved in obesity. (In french: Caractérisation phénotypique et recherche de REManiements chromosomiques chez des patients présentant une OBésité syndromique de cause non identifiée : REMOB)

Detailed Description
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With the introduction of array comparative genomic hybridization (CGH), genome-wide high resolution analysis for DNA copy number alterations became feasible. This technology has been principally used in patients with mental retardation. Depending on the eligibility criteria and resolution of the array, around 10 % of patients with mental retardation are found with cryptic chromosomal imbalance. This figure arises 20 % for patients with mental retardation and multiple congenital anomalies. Alteration of the lipid metabolism and/or regulation of satiety, obesity (except in presence of other exogen factors) can be considered as a developmental disorder. Also, different syndromes with obesity have been associated with chromosomal abnormalities, such as 1p36 deletion syndrome, 2q37 deletion syndrome, chromosome 14 maternal disomy … So we can expect that syndromic obesity is similarly associated with sub cryptic chromosomal abnormalities. Some isolated patients with obesity have been described with cryptic chromosomal imbalance found by array CGH, but no study has been realized in cohorts of patients selected for syndromic obesity. Characterization of cryptic chromosomal anomaly(ies) in a patient will also be useful to precise the management and follow-up of the patient and to give the family an adapted genetic counselling. We will define a cohort of patients with syndromic obesity and propose them to realize a first screening looking for the common aetiologies of syndromic obesity. If this screening is normal, array CGH will be realized. This analysis implies a blood sampling of 5 ml in patient and his parents. Genes present at the deleted or duplicated loci characterized in the patients will be study to determine if some could be specifically implicated in the development of obesity. These same genes could be implicated in isolated obesity. Our study will be also useful to precise the aetiological screening of syndromic obesity, and determine the place of array-CGH.

Official Title
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Phenotypic Characterization and Array CGH Analysis in Patients With Syndromic Obesity of Unknown Etiology

Conditions
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Mental Retardation, Syndromic Obesity

Intervention / Treatment
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* Genetic: Clinical examination and blood sampling for biological and genetic analysis


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: children (under 18 year-old) obesity (following IOTF definition) at least one criteria among : mental retardation facial dysmorphism at least one major malformation (uro-genital, cardiac, skeletal, cerebral, ophthalmologic…) Exclusion Criteria: common obesity obesity with an identified aetiology

Ages Eligible for Study
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Maximum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Intervention/Treatment |
| --- |
|Genetic: Clinical examination and blood sampling for biological and genetic analysis|Clinical examination and precise description of the phenotype (questionnaire) Standardized screening with : radiological (hands, feet, spine ; and renal ultrasonography) biological (hormonal, metabolic, and basic genetic investigations (karyotype, FISH 22q11.2, Fragile X, and other depending on the clinical data))|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evaluation of the prevalence of cryptic chromosomal imbalance in patients with syndromic obesity of unknown etiology. |  | 3 - 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| prevalence of the main genetic aetiologies of syndromic obesity |  | 3 - 6 months | 
| Characterization of the main features evocative of subcryptic chromosomal anomalies in this population |  | 3 - 6 months | 
| Phenotypic description of some new syndromes with obesity |  | 3 - 6 months | 
| candidate genes implicated in the development of obesity. |  | 3 - 6 months | 
| Delineation of an aetiological screening protocol in patients with syndromic obesity |  | 3 - 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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CGH array technology, mental retardation, chromosomal abnormalities, syndromic obesity, obesity