Genetics of human growth

Influence of ecoregional and lifestyle factors on growth and body composition of I ndian children and adolescents aged 9–18 years—A multicenter study

OBJECTIVES

Ecoregion comprises all the environmental factors such as climate, vegetation, geomorphology, and soil taken together. The objectives of this study were to (1) assess differences in growth and body composition (BC) in 9-18-year-old children and adolescents (CA), across six ecoregions of India, (2) evaluate and compare the magnitude of the effect of ecoregional and lifestyle factors (LSF) on growth and BC in urban (U) and rural (R) children and adolescents, and (3) reassess the applicability of Bergmann's Rule and Allen's Rule to humans.

SUBJECTS AND METHODS

Data on 1845 CA (925 boys; 920 girls) were collected (2016-2017) from urban and rural areas of six ecoregions of India. Anthropometric and BC parameters were measured; Z-scores were computed. Lifestyle Index score (LIS) based on LSF-(socioeconomic status [SES], diet, physical activity) was computed (categorized as low, medium, high-indicates better LSF). Univariate analysis was performed to estimate effect size.

RESULTS

Significant differences were observed in growth and BC across urban and rural ecoregions. CA with high LIS were taller and heavier than those with low LIS (p < .05). Ecoregion had greater effect on growth (Partial eta square (η² ) for R = 0.136 vs. U = 0.057) and BC (η² for R = 0.094 vs. U = 0.058) of rural CA than urban (p < .01). LSF had more effect on the BC of urban CA (η²  = 0.017) than rural (η²  = 0.002, p < .01).

CONCLUSION

Disparities among the six ecoregions were not large enough to fully support Bergmann's Rule and Allen's Rule. Ecoregion had greater effect on growth and BC of rural CA than urban, while lifestyle factors had more effect on the BC of urban CA.

X-linked mental retardation and severe short stature with a novel mutation of the KDM5C gene

Many monogenetic disorders of short stature have autosomal recessive/dominant form of inheritance. However, X-linked short stature has not been well recognized. Herein, we report a case of a boy from a family with familial severe short stature and mental retardation, who displayed an X-linked recessive trait. The boy at the age of 4 yr and 6 mo presented with remarkable growth failure (height: 76.5 cm [–6.3 SD]) and mental retardation (IQ: 30) and cerebellar volume loss and without an external anomaly or microcephaly to our hospital. A careful interview to determine the family history suggested a genetic background of familial mental retardation and short stature. His mother had mild intellectual disability with normal stature and his maternal uncle had severe mental retardation with remarkably short stature. Whole-exome sequencing identified a pathogenic variant in the KDM5C gene, NM_004187: exon 23: c.3874_3875del: (p.Ala1292Glnfs*7). He presented with a novel frameshift mutation. His mother was a heterozygous carrier of the variant. This case suggests that a disorder associated with the KDM5C gene should be considered when patients present with remarkably short stature and X-linked mental retardation.

Anthropometric measurements of school-going-girls of the Punjab, Pakistan

BACKGROUND

Child's growth has been considered an important indicator to evaluate health trends in a population and to devise strategies accordingly. The purpose of the present study was to determine most commonly occurring weight abnormalities among school-going girls from Punjab and to compare with international growth references devised by World Health Organization (WHO) and Centre for Disease Control and Prevention (CDC).

METHODS

In this cross-sectional study a sample of 10,050 child and adolescent girls from 12 districts, 35 public/private sector schools, located in rural, semi-urban and urban areas of northern, central and southern Punjab were included. Parameters were measured according to standardised techniques and centile curves obtained by Lambda, Mu, Sigma (LMS) method.

RESULTS

The results showed an increase in weight, height and BMI of the Punjabi girls until 15 years. When compared with international growth references, weight and BMI in our population were significantly lowered; however, height was lower during 12-16 years of age and the differences observed were more pronounced with CDC as compared to WHO. When 3rd, 50th and 90th percentiles of weight, height and BMI in our population were compared with international standards, the values were lower in our paediatric population.

CONCLUSION

The Punjabi schoolgirls significantly differed from CDC and WHO references, and this difference should be taken into consideration for evaluation of growth abnormalities in our paediatric population. However, in the absence of national reference data, WHO standards have been considered more appropriate for comparison.

Exploring the Genetic Correlation Between Growth and Immunity Based on Summary Statistics of Genome-Wide Association Studies

The relationship between growth and immune phenotypes has been presented in the context of physiology and energy allocation theory, but has rarely been explained genetically in humans. As more summary statistics of genome-wide association studies (GWAS) become available, it is increasingly possible to explore the genetic relationship between traits at the level of genome-wide summary statistics. In this study, publicly available summary statistics of growth and immune related traits were used to evaluate the genetic correlation coefficients between immune and growth traits, as well as the cause and effect relationship between them. In addition, pleiotropic variants and KEGG pathways were identified. As a result, we found negative correlations between birthweight and immune cell count phenotypes, a positive correlation between childhood head circumference and eosinophil counts (EO), and positive or negative correlations between childhood body mass index and immune phenotypes. Statistically significant negative effects of immune cell count phenotypes on human height, and a slight but significant negative influence of human height on allergic disease were also observed. A total of 98 genomic regions were identified as containing variants potentially related to both immunity and growth. Some variants, such as rs3184504 located in SH2B3, rs13107325 in SLC39A8, and rs1260326 located in GCKR, which have been identified to be pleiotropic SNPs among other traits, were found to also be related to growth and immune traits in this study. Meanwhile, the most frequent overlapping KEGG pathways between growth and immune phenotypes were autoimmune related pathways. Pleiotropic pathways such as the adipocytokine signaling pathway and JAK-STAT signaling pathway were also identified to be significant. The results of this study indicate the complex genetic relationship between growth and immune phenotypes, and reveal the genetic background of their correlation in the context of pleiotropy.

Target height and target range for Japanese children: revisited

In 1990, we proposed the equations to calculate target height (TH) and target range (TR) for Japanese, taking account of the positive height secular trend observed over the last ∼100 years. However, height difference between generations appears to have become small or negligible in contemporary Japanese populations. Thus, we re-analyzed the Japanese height data, and revised the equations for TH and TR for contemporary Japanese children as follows (cm): Boys, TH = {PH + (MH + 13)} ÷ 2, TR = TH ± 9; and Girls, TH = {(PH – 13) + MH} ÷ 2; TR = TH ± 8, where PH indicates paternal height and MH maternal height.