Whether a person is obese or lean is determined by Body Mass Index which is abbreviated as “BMI”. If BMI of the individual exceeds from 30 kg/m2 then person is considered to be obese and lean when less than 18 kg/m2 (World Health Organization, 2000). Leptin protein codes for a 167 amino acids, finally processed into the 146 amino acids . It is a 16-kDa protein secreted by white adipocytes and dominantly have major role in the body weight regulation [2,3]. Another name of the leptin gene is Ob gene. It is located on chromosome no. 7 its cytogenetic location is 7q31.3. In lean adults it circulates in the body range 5-15 ng/mL . Almost 40 chemicals are present for the behavior control in the brain.
These chemicals are called neurotransmitters. 12 out of 40 have been found to control eating behavior. Leptin is one of these neurotransmitters. This neurotransmitter signals to the brain mainly in the hypothalamus, when a person stops to eat to maintain his BMI (www.loop.com/%7Ebkrentzman/obesity/genetics.html). Sequence of amino acids of the leptin protein is highly conserved among species so rare chance that mutation will be present in this gene. There is a 67% sequence homology among species . Activity of this gene is started after binding with a receptor known as Leptin Receptor (LEPR). Due to alternative splicing of LEPR, six different isoforms formed. These isoforms are LEPRa, LEPRb, LEPRc, LEPRd, LEPRe and LEPRf. Only the LEPRb is the important and longest isoform that have the capacity of strong signaling so defect in signaling cause severe obesity .
Citation: Wasim M, Fakhar N (2014) Leptin Gene Mutations in Morbidly Obese and Severely Lean Individuals from Punjab, Pakistan. J Obes Weight Loss Ther 4:233. doi: 10.4172/2165-7904.1000233