Genome Study in Constitutional Thinness

Centre Hospitalier Universitaire de Saint Etienne210 enrolled

Overview

Constitutional thinness (CT) is a recently defined entity as a differential diagnosis of anorexia nervosa (AN), considered to be the most frequent cause of low body mass index (BMI) in young women. CT subjects present no AN psychiatric traits, preserved menses, no biological signs of undernutrition and balanced energy metabolism despite a Body Mass Index (BMI) \<17 kg / m². CT familial aggregation, low body mass without a hormonal explanation, and specific appetite regulation profile suggest a specific genetic profile in these subjects. Objective: A family linkage study in order to identify genes involved in the constitutional thinness phenotype by using genome wide scan (GWAS) techniques Studied population: Fifty families including at least one well phenotyped CT index case (grade 2 or 3 of thinness according WHO classification). Blood or saliva is sampled for DNA extraction. Perspectives: Revealing eventual abnormalities could lead to a more precise diagnosis of constitutional thinness and new hypothesis in understanding extreme bodyweight mechanisms.

Study Type

OBSERVATIONAL

Enrollment

210

Conditions

Thinness Leanness

Interventions

Eligibility

Sex: ALLMin age: 18 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * For all subjects: * age \> 18 yrs * affiliation to health insurance * member of a family including at least 2 CT members and overall 3 evaluable members over 2 generations * written and signed consent * For CT subjects : * grade 2 or 3 of thinness according WHO classification * women, BMI \< 17 kg/m² at 20-30 yrs or \< 19 for older subjects * men, BMI \< 18 kg/m² at 20-30 yrs or \< 20 for older subjects * absence of DSM criteria for anorexia nervosa * young women : normal menses and fat mass percentage 15 % ; absence of DSM criteria for anorexia nervosa * men : normal testosterone level * For subjects without CT : * women, BMI \> 19 kg/m² * men, BMI \> 20 kg/m² Exclusion Criteria: * CT subjects: * smoking \> 5 cigarettes / day * history of emaciating pathologies * intense physical activity \> 7 hours / week * For all subjects : * refuse of written consent

Outcomes

Primary Outcomes

chromosome regions' abnormalities

The linkage study is performed in order to identify one or several chromosome regions linked the constitutional thinness phenotype by using genome wide scan (GWAS) techniques in CT families members.

Time frame: day 1

Secondary Outcomes

genetic markers

Identify within upper mentioned regions more specific genetic markers (mutation/variant) to characterize genes involved in CT phenotype