María Daniela Bechara Mestra

Melissa Cano Bustamante

Medicine Students

3 semester

INTRODUCTION

Obesity is one of the most common diseases in our society. Sedentarism

and fatty diet are involved in most of cases as the etiology of this disease

and most of the times treatment is focused in these problems, but there are

some cases in which obesity appears in an early age and parents have a

normal weight. For this reason scientists have made several studies trying to

find a explanation to this, for instance genetic mutations as a etiology of

this condition. Mutations in leptin gen are involved in etiology of early onset

extreme obesity.

INTRODUCTION: LEPTIN

Leptin is a hormone that is synthesized by adipocytes in order to inform to

the brain the energy levels derived from fats, in this way, this hormone

controls oral intake and body weight.

Leptin is a 167 aminoacid protein produced by LEP gen in cromosome 7.

this protein has four alfa hélix and a disulfide bond that is needed to be

biologically active.

Leptin receptor (hLR) is located in hypotalamus cells in central nervous

sistem and it is produced by its gen (LEPR).

INTRODUCTION

OBESITY

Abnormal or excessive fat accumulation that may impair health (OMS).

A BMI greater than or equal to 30 is obesity

OBESITY

Early onset extreme obesity is a

special condition in which

children rapidly gain weight in the

posnatal period despite of normal

weight at birth.

CONGENITAL DEFICIENCY

This is a condition in which a substance is in a low concentration at birth.

It can be caused by:

Genetic: gene mutations,chromosomal mutations

Physical: radiation

Chemicals: drugs, toxic

Infectious: rubella, syphilis

Teratogenic agents: alcohol, synthetic estrogens, HIV

CONGENITAL DEFICIENCY

When this substance is partially or

totally reduced will generate

abnormal function in its target

(organ or system) and in this way

can cause disease.

EARLY ONSET EXTREME OBESITY

This is a disease that is present in children with a normal weight at bird but

has a rapid weight gain, also parents have a normal weight.

Several studies had found, congenital leptin deficiency or a biologically

inactive protein or mutant leptin receptor in cells is present in these children

with the disease.

OBJECTIVE

To study how congenital leptin

deficiency generates early onset

extreme obesity.

MATERIALES Y MÉTODOS

Características del paciente:

Primer hijo de 2 embarazos.

(padres sanos).

Peso al nacer 3680gr (normal).

Rápida ganancia de peso.

Mutación en el gen LEP.

2 años y 6 meses. IMC: 38.6 > 99.9

Hiperfagia

Recurrentes infecciones.

MATERIALES Y MÉTODOS

Secuenciación de DNA

Objetivo:

Determinar la secuencia de losnucleótidos.

2 métodos:

Desdoblamiento químico

Enzimático (DNA polimerasa).

MATERIALES Y MÉTODOS

Muestra de DNA.

Nucleótidos libres.

Enzima.

Primer.

MATERIALES Y MÉTODOS

Desdoblamiento Químico Enzimático

MATERIALES Y MÉTODOS

MATERIALES Y MÉTODOS

MATERIALES Y MÉTODOS

Análisis de Western Blot

Determina proteínas específicas

en una muestra.

Electroforesis de la muestra con

proteínas.

Transferir a membrana.

Coloración.

Incubación con anticuerpo.

Detección del anticuerpo.

Revelado.

MATERIALES Y MÉTODOS

Preparación de la muestra

MATERIALES Y MÉTODOS

Electroforesis en gel de acrilamida

MATERIALES Y MÉTODOS

Transferencia electroforética a una membrana

MATERIALES Y MÉTODOS

Hibridación del anticuerpo

MATERIALES Y MÉTODOS

Detección de las bandas

MATERIALES Y MÉTODOS

Producción y purificación de proteínas recombinantes de leptina.

Se realizó por medio de la introducción del gen de leptina normal

y mutante en el ADN de un baculovirus.

Este virus infecta células de trichoplusia ni.

La célula replica, transcribe y traduce ese ADN con el gen de

leptina, para que se produzcan ambas proteínas en gran cantidad.

finalmente son extraídas por medio de cromatografía secuencial.

MATERIALES Y MÉTODOS

Estudios en animales

La leptina obtenida se inyectó en ratones hembra de 8 semanas de edad.

A 6 ratones se les inyecto 0.2µ/gr de leptina normal y la misma dosis de

leptina (D100Y).

Las dosis fueron incrementadas a 0.6µ/gr por tres días.

se monitorizo el peso y la cantidad de comida ingerida por los ratones

el experimento fue aprobado por las autoridades locales.

RESULTADOS

RESULTADOS

RESULTADOS

DISCUSSION

Author ¿What Said? Yes - No

Fischer-Posovszky

P, et al

“The circulating leptin levels in our patient werewithin the range of levels found in other childrenwith extreme obesity not related to leptindeficiency”.7

No

Weigle DS,et al

“Leptin mutant was not functional and thus

could not mediate a satiety signal in the

central nervous system”.18

Yes

Farooqi IS

“Current clinical recommendations advise thatleptin serum concentrations be measured inchildren who have rapid weight gain in the firstmonths of life, to identify patients with congenitalleptin deficiency “.17

Yes

Wang J, et al

“Finally, treatment of the patient with metreleptinwas successful, resulting in a rapid change ineating behavior and significant weight loss.”19

Yes

CONCLUSIONS

Research about leptin should be a major priority of science since obesity

figures are on a sharp increase not only in adults but also in the children.

Create a exogenous leptin able to control satiety and hyperphagia in

people with a deficiency of it would lead to progress the development of

new treatments for obesity and overweight.

CONCLUSIONS

This study is important, because it gives new information about obesity, one

of the most common diseases in our society, specially, DNA mutations that

could explain obesity in children.

New alternatives to treat obesity, derived from discoveries in molecular

mechanisms involved in this disease could be performed in patients with

obesity that doesn’t respond to conventional drugs.

María Daniela Bechara Mestra

Melissa Cano Bustamante