Los pacientes con delgadez constitucional presentan un fenotipo diferente al de los pacientes con trastornos de la alimentación / Patients with constitutional thinness have a different phenotype than patients with eating disorders

Los pacientes con delgadez constitucional suelen presentar un peso habitual reducido pero estacionario en el tiempo, con dificultad para aumentarlo incluso luego de someterse a dietas hipercalóricas. A diferencia de otras entidades, no se suelen encontrar trastornos de la alimentación, enfermedades sistémicas, desnutrición o sobre-ejercitación. Sin embargo, su presencia suele despertar preocupación y motivar la búsqueda de causas patológicas asociadas, tanto por parte delos pacientes como de los profesionales de la salud. Partiendo de la viñeta clínica de una paciente que presenta estas características, el autor realiza una búsqueda bibliográfica para intentar esclarecer cuán diferentes resultan los pacientes con delgadez constitucional de aquellos que presentan el principal diagnóstico diferencial a tener en cuenta, la anorexia nerviosa. (AU)

Patients with constitutional thinness tend to have a reduced but stationary habitual weight over time, with difficulty to increase it even after undergoing hypercaloric diets. Unlike other entities, eating disorders, systemic diseases, malnutrition or over-exercising are not usually found. However, its presence tends to arouse concern and motivates the search for associated pathological causes, both by patients and health professionals. Based on the clinical vignette of a patient who presents these characteristics, the author performs a literature search in order to clarify how different patients with constitutional thinness are from those who present the main differential diagnosis to consider:anorexia nervosa. (AU)

A family-based association study of the HTR1B gene in eating disorders

Objective: To explore the association of three polymorphisms of the serotonin receptor 1Dβ gene (HTR1B) in the etiology of eating disorders and their relationship with clinical characteristics. Methods: We analyzed the G861C, A-161T, and A1180G polymorphisms of the HTR1B gene through a family-based association test (FBAT) in 245 nuclear families. The sample was stratified into anorexia nervosa (AN) spectrum and bulimia nervosa (BN) spectrum. In addition, we performed a quantitative FBAT analysis of anxiety severity, depression severity, and Yale-Brown-Cornell Eating Disorders Scale (YBC-EDS) in the AN and BN-spectrum groups. Results: FBAT analysis of the A-161T polymorphism found preferential transmission of allele A-161 in the overall sample. This association was stronger when the sample was stratified by spectrums, showing transmission disequilibrium between the A-161 allele and BN spectrum (z = 2.871, p = 0.004). Quantitative trait analysis showed an association between severity of anxiety symptoms and the C861 allele in AN-spectrum participants (z = 2.871, p = 0.004). We found no associations on analysis of depression severity or preoccupation and ritual scores in AN or BN-spectrum participants. Conclusions: Our preliminary findings suggest a role of the HTR1B gene in susceptibility to development of BN subtypes. Furthermore, this gene might have an impact on the severity of anxiety in AN-spectrum patients.

Genetics in eating disorders: extending the boundaries of research / Genética em transtornos alimentares: ampliando os horizontes de pesquisa

OBJECTIVE: To review the recent literature relevant to genetic research in eating disorders and to discuss unique issues which are crucial for the development of a genetic research project in eating disorders in Brazil. METHOD: A computer literature review was conducted in the Medline database between 1984 and may 2005 with the search terms "eating disorders", "anorexia nervosa", "bulimia nervosa", "binge eating disorder", "family", "twin" and "molecular genetic" studies. RESULTS: Current research findings suggest a substantial influence of genetic factors on the liability to anorexia nervosa and bulimia nervosa. Genetic research with admixed populations should take into consideration sample size, density of genotyping and population stratification. Through admixture mapping it is possible to study the genetic structure of admixed human populations to localize genes that underlie ethnic variation in diseases or traits of interest. CONCLUSIONS: The development of a major collaborative genetics initiative of eating disorders in Brazil and South America would represent a realistic possibility of studying the genetics of eating disorders in the context of inter ethnic groups, and also integrate a new perspective on the biological etiology of eating disorders.

OBJETIVO: Revisar a literatura atual concernente à pesquisa genética em transtornos do comportamento alimentar e discutir questões relevantes ao desenvolvimento de um projeto de pesquisa genética nessa área no Brasil. MÉTODO: A revisão realizada utilizou a base de dados Medline, no período de 1984 a maio de 2005, com os seguintes termos de busca: "anorexia nervosa", "bulimia nervosa", "eating disorders", "binge eating disorder", "family studies", "twin studies", "molecular genetics studies". RESULTADOS: Os dados atuais apontam para uma contribuição relevante dos fatores genéticos na suscetibilidade à anorexia e à bulimia nervosa. A pesquisa genética com populações miscigenadas deve levar em consideração o tamanho da amostra, a densidade de genotipagem e a estratificação populacional. Através de "admixture mapping" é possível estimar a estrutura genética destas populações e localizar genes relacionados à variação étnica de doenças ou traços de interesse. CONCLUSÕES: O desenvolvimento de uma grande iniciativa de colaboração em genética de transtornos alimentares no Brasil e na América Latina viabilizará estudar os fatores genéticos em transtornos do comportamento alimentar no contexto de grupos inter-étnicos, e integrar uma nova perspectiva biológica à etiologia destes distúrbios.

Anorexia nervosa: III. aspectos epidemiológicos, genéticos e sócio-culturais / Anorexia nervosa: III. epidemiological, genetic and socio-cultural aspects

Faz-se um levantamento de dados epidemiológicoss, genéticos e sócio-culturais referentes à anorexia nervosa. Pretende-se avaliar a participaçäo de tais fatores na gênese e no desenvolvimento da condiçäo. Conclui-se que os fatores sócio-culturais participam do aumento da incidência observado, mas que a contribuiçäo näo pode ser tida como causa. Por outro lado, os dados epidemiológicos e os estudosde gêmeos näo estäo aprimorados o suficiente para permitir a diferenciaçäo entre as influências genotípicas e as fenotípicas