According to a publication from Genetic Obesity News, a new genetic mutation has been discovered in an Iranian family that has differing affects on early-onset obesity based on sex.
Leptin, Leptin Receptors, and Leptin Receptor Deficiency
The discovery was made when several members of the same family were screened and had identical mutations in their LEPR genes. This gene, located on the first chromosome in humans, is responsible for coding the production of leptin receptors.
Leptin is a hormone associated with hunger inhibition and energy balance. People with a deficiency of properly-functioning leptin receptors are constantly hungry – without a way for their body to process signals sent as leptin, they quickly gain weight.
Because of the family’s mutated LEPR genes, their leptin receptors were malfunctioning. However, scientists soon found that different members of the family had wildly different experiences with the mutation.
On the Basis of Sex
The researchers focused on four affected individuals: two men, ages 32 and 36, and two women, ages 25 and 34.
The women were hit particularly hard by the affects of the mutation. They experienced delayed puberty, and over the course of their lives their BMIs (body mass indices) continued to grow unchecked. Additional tests found that the women had low levels of anti-mullerian hormone – a protein produced by the cells that surround each egg. The measurements reflected a depletion of the women’s ovarian follicles, causing infertility.
The men experienced the same steady weight gain through puberty. However, the men both experienced a drop in their weights around puberty. And what’s more, both underwent puberty somewhere between 13 and 15 years – well within the normal age range for boys. Both men have children as well, confirming their fertility.
Researchers claimed that differences between the sexes in prognosis stemming from the same mutation “[had] not been described before.”
Improving Our Understanding of Leptin Deficiency
Previous studies in animals had already suggested that leptin deficiency could be expressed differently between the sexes – leptin-deficient females were found to be infertile, while a few of the male mice were still able to produce offspring.
Our understanding of the differences in humans, however, is still being developed. The researchers who published the study noted that such differences may be the basis of leptin’s differing roles in men and women, and called for increased research into the effects of deficiency on fertility.
Obesity is one of the largest health threats facing the United States in the modern era. How does improving our understanding of obesity and its origins improve our outlook in the fight against it? Share your thoughts with Patient Worthy!
