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Mutations in genes such as LIN28, [25] [26] and LEP and LEPR, which encode leptin and the leptin receptor, [27] have been associated with precocious puberty. The association between LIN28 and puberty timing was validated experimentally in vivo, when it was found that mice with ectopic over-expression of LIN28 show an extended period of pre ...
Mini-puberty is a transient hormonal activation of the hypothalamic-pituitary-gonadal (HPG) axis that occurs in infants shortly after birth. This period is characterized by a surge in the secretion of gonadotropins (LH and FSH) and sex steroids (testosterone in males and estradiol in females), similar to but less intense than the hormonal changes that occur in puberty during adolescence.
Early adolescence (puberty begins, 10 to 13 years): 4 - 6 ml; Middle adolescence (puberty changes continue, 14 to 17 years): 8 - 10 ml; Late adolescence/young adulthood (18 to 21 years and beyond): 12 - 15 ml; Adulthood: 20 - 25 ml; People with macroorchidism have testicular volume larger than 4 ml before puberty. [11]
5α-reductase deficiency (5-ARD) – an autosomal recessive condition caused by a mutation of the 5-alpha reductase type 2 gene. It only affects people with Y chromosomes, namely genetic males. People with this condition are fertile, with the ability to father children, but may be raised as females due to ambiguous or feminized genitalia. [18] [19]
The fetal origins hypothesis (differentiated from the Developmental Origins of Health and Disease hypothesis, which emphasizes environmental conditions both before and immediately after birth) proposes that the period of gestation has significant impacts on the developmental health and wellbeing outcomes for an individual ranging from infancy to adulthood.
Children born with some hair colors may find it gradually darkens as they grow. Many blond, light brown, or red haired infants experience this. This is caused by genes being turned on and off during early childhood and puberty. [20] Changes in hair color typically occur naturally as people age, eventually turning the hair gray and then white.
A complementary way to describe effects of individual genetic variants is in how much change one expects on the behavioural outcome given a change in the number of risk alleles an individual harbours, often denoted by the Greek letter (denoting the slope in a regression equation), or, in the case of binary disease outcomes by the odds ratio of ...
The number of genes known to cause cases of KS/CHH is still increasing. [16] In addition it is thought that some cases of KS/CHH are caused by two separate gene defects occurring at the same time. [8] Individual gene defects can be associated with specific symptoms which can help in identifying which genes to test for.