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Growth pattern from birth to adulthood in African pygmies of known age.

Rozzi FV, Koudou Y, Froment A, Le Bouc Y, Botton J - Nat Commun (2015)

Bottom Line: Body size at birth among the Baka is within standard limits, but their growth rate slows significantly during the first two years of life.It then more or less follows the standard pattern, with a growth spurt at adolescence.Their life history variables do not allow the Baka to be distinguished from other populations.

View Article: PubMed Central - PubMed

Affiliation: UPR 2147 CNRS, 44 rue de l'Amiral Mouchez, 75014 Paris, France.

ABSTRACT
The African pygmy phenotype stems from genetic foundations and is considered to be the product of a disturbance in the growth hormone-insulin-like growth factor (GH-IGF) axis. However, when and how the pygmy phenotype is acquired during growth remains unknown. Here we describe growth patterns in Baka pygmies based on two longitudinal studies of individuals of known age, from the time of birth to the age of 25 years. Body size at birth among the Baka is within standard limits, but their growth rate slows significantly during the first two years of life. It then more or less follows the standard pattern, with a growth spurt at adolescence. Their life history variables do not allow the Baka to be distinguished from other populations. Therefore, the pygmy phenotype in the Baka is the result of a change in growth that occurs during infancy, which differentiates them from East African pygmies revealing convergent evolution.

No MeSH data available.


Related in: MedlinePlus

Growth trajectories in Baka pygmies.(a) Growth in weight during period A. (b) Growth in weight during period B. (c) Growth in height during period B. (d) Changes in BMI during growth. Growth trajectories show low residual standard deviations (RSD) and are different for boys (solid lines) and girls (dashed lines). Growth spurt in weight and height are clearly observable during adolescence and steady dimension are reached from 18 to 19 years in girls and 20 to 22 years in boys. T.O.: pubertal weight/height gain spurt, P.V.: peak weight/height growth velocity; BMI, body mass index.
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f1: Growth trajectories in Baka pygmies.(a) Growth in weight during period A. (b) Growth in weight during period B. (c) Growth in height during period B. (d) Changes in BMI during growth. Growth trajectories show low residual standard deviations (RSD) and are different for boys (solid lines) and girls (dashed lines). Growth spurt in weight and height are clearly observable during adolescence and steady dimension are reached from 18 to 19 years in girls and 20 to 22 years in boys. T.O.: pubertal weight/height gain spurt, P.V.: peak weight/height growth velocity; BMI, body mass index.

Mentions: The average growth curves for the Baka compared with European references are presented in Figs 1 and 2. Boys (N=246) are heavier than girls (N=235) during period A (from birth to 3 years of age) (Fig. 1a). Before 6 months, weight growth is faster in boys than in girls; afterwards, conversely, weight growth is faster in girls, whose weight almost catches up with that of boys by the end of period A. During period B (from 2 years of age to adulthood; Fig. 1b) the weight growth peaks at 12.9 years for girls (N=271) and 15.3 years for boys (N=283), with a corresponding rate of weight growth of 3.89 and 3.85 kg per year, respectively. The pubertal weight gain spurt begins at 8.0 years of age in girls (estimated weight=18.5 kg, s.d.=2.4) and 10.6 years in boys (estimated weight=22.1 kg, s.d.=3.4). Boys become heavier than girls from the age of 18 years. Weight become stable from the age of 19 years in girls (estimate weight=45.9 kg, s.d.=4.8) and 22 years in boys (estimate weight=52.9 kg, s.d.=6.6). Thus, from the start of the pubertal weight gain spurt to adulthood, girls gain around 27 kg in weight and boys around 30 kg. In girls (N=274), the peak of height velocity is 5.64 cm per year on average at the age of 12 years, and 5.63 cm per year on average in boys (N=275), 3 years later than in girls (Fig. 1c). The presence of peak velocity at puberty is not bound to the selected model. The start of the pubertal spurt in height gain occurs at 9.0 years in girls (estimated height=116 cm, s.d.=5.4) and at 11.6 years in boys (estimated height=122.8 cm, s.d.=5.7); this explains the higher values in girls from 10 to 16 years of age. Note that girls are taller than boys from the age of 5 years, finding that is uncommon but not unknown elsewhere27. Boys grow taller than girls from the age of 16 years. Adult height in girls is attained at around 18 years of age (estimated height=146.7 cm, s.d.=4.7) and at 20 in boys (estimated height=153.5 cm, s.d.=6.2). Girls and boys become about 30 cm taller from the start of the pubertal spurt in height up to adulthood. Therefore, our results clearly document the presence of a growth spurt in Baka pygmies. A body mass index (BMI) growth model was obtained from the model coefficients for predicted weight and height gain in period B (Fig. 1d). The BMI trajectory shows a similar pattern before the onset of puberty; after this, BMI in girls starts to increase earlier than in boys, who reach adult BMI values much earlier.


Growth pattern from birth to adulthood in African pygmies of known age.

Rozzi FV, Koudou Y, Froment A, Le Bouc Y, Botton J - Nat Commun (2015)

Growth trajectories in Baka pygmies.(a) Growth in weight during period A. (b) Growth in weight during period B. (c) Growth in height during period B. (d) Changes in BMI during growth. Growth trajectories show low residual standard deviations (RSD) and are different for boys (solid lines) and girls (dashed lines). Growth spurt in weight and height are clearly observable during adolescence and steady dimension are reached from 18 to 19 years in girls and 20 to 22 years in boys. T.O.: pubertal weight/height gain spurt, P.V.: peak weight/height growth velocity; BMI, body mass index.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525207&req=5

f1: Growth trajectories in Baka pygmies.(a) Growth in weight during period A. (b) Growth in weight during period B. (c) Growth in height during period B. (d) Changes in BMI during growth. Growth trajectories show low residual standard deviations (RSD) and are different for boys (solid lines) and girls (dashed lines). Growth spurt in weight and height are clearly observable during adolescence and steady dimension are reached from 18 to 19 years in girls and 20 to 22 years in boys. T.O.: pubertal weight/height gain spurt, P.V.: peak weight/height growth velocity; BMI, body mass index.
Mentions: The average growth curves for the Baka compared with European references are presented in Figs 1 and 2. Boys (N=246) are heavier than girls (N=235) during period A (from birth to 3 years of age) (Fig. 1a). Before 6 months, weight growth is faster in boys than in girls; afterwards, conversely, weight growth is faster in girls, whose weight almost catches up with that of boys by the end of period A. During period B (from 2 years of age to adulthood; Fig. 1b) the weight growth peaks at 12.9 years for girls (N=271) and 15.3 years for boys (N=283), with a corresponding rate of weight growth of 3.89 and 3.85 kg per year, respectively. The pubertal weight gain spurt begins at 8.0 years of age in girls (estimated weight=18.5 kg, s.d.=2.4) and 10.6 years in boys (estimated weight=22.1 kg, s.d.=3.4). Boys become heavier than girls from the age of 18 years. Weight become stable from the age of 19 years in girls (estimate weight=45.9 kg, s.d.=4.8) and 22 years in boys (estimate weight=52.9 kg, s.d.=6.6). Thus, from the start of the pubertal weight gain spurt to adulthood, girls gain around 27 kg in weight and boys around 30 kg. In girls (N=274), the peak of height velocity is 5.64 cm per year on average at the age of 12 years, and 5.63 cm per year on average in boys (N=275), 3 years later than in girls (Fig. 1c). The presence of peak velocity at puberty is not bound to the selected model. The start of the pubertal spurt in height gain occurs at 9.0 years in girls (estimated height=116 cm, s.d.=5.4) and at 11.6 years in boys (estimated height=122.8 cm, s.d.=5.7); this explains the higher values in girls from 10 to 16 years of age. Note that girls are taller than boys from the age of 5 years, finding that is uncommon but not unknown elsewhere27. Boys grow taller than girls from the age of 16 years. Adult height in girls is attained at around 18 years of age (estimated height=146.7 cm, s.d.=4.7) and at 20 in boys (estimated height=153.5 cm, s.d.=6.2). Girls and boys become about 30 cm taller from the start of the pubertal spurt in height up to adulthood. Therefore, our results clearly document the presence of a growth spurt in Baka pygmies. A body mass index (BMI) growth model was obtained from the model coefficients for predicted weight and height gain in period B (Fig. 1d). The BMI trajectory shows a similar pattern before the onset of puberty; after this, BMI in girls starts to increase earlier than in boys, who reach adult BMI values much earlier.

Bottom Line: Body size at birth among the Baka is within standard limits, but their growth rate slows significantly during the first two years of life.It then more or less follows the standard pattern, with a growth spurt at adolescence.Their life history variables do not allow the Baka to be distinguished from other populations.

View Article: PubMed Central - PubMed

Affiliation: UPR 2147 CNRS, 44 rue de l'Amiral Mouchez, 75014 Paris, France.

ABSTRACT
The African pygmy phenotype stems from genetic foundations and is considered to be the product of a disturbance in the growth hormone-insulin-like growth factor (GH-IGF) axis. However, when and how the pygmy phenotype is acquired during growth remains unknown. Here we describe growth patterns in Baka pygmies based on two longitudinal studies of individuals of known age, from the time of birth to the age of 25 years. Body size at birth among the Baka is within standard limits, but their growth rate slows significantly during the first two years of life. It then more or less follows the standard pattern, with a growth spurt at adolescence. Their life history variables do not allow the Baka to be distinguished from other populations. Therefore, the pygmy phenotype in the Baka is the result of a change in growth that occurs during infancy, which differentiates them from East African pygmies revealing convergent evolution.

No MeSH data available.


Related in: MedlinePlus