Confirmation linkage study in support of the X chromosome harbouring a QTL underlying human height variation

Association of Parental Height With Offspring Stunting in 14 Low- and Middle-Income Countries

Background: Maternal height has been confirmed to be associated with offspring stunting in low- and middle-income countries (LMICs), but only limited studies have examined the paternal-offspring association, and few studies have examined the joint effect of maternal and paternal height on stunting.

Objective: To investigate the association between parental height and stunting of children aged under five in LMICs.

Methods: We obtained data from the Demographic and Health Surveys (DHS) conducted in 14 LMICs from 2006 to 2016. The association between maternal and paternal height and height-for-age z score (HAZ) of children aged under five was analyzed using a linear regression model in consideration of complex survey design, and regression coefficients (β) with 95% confidence intervals (CIs) were reported. Then, the association between maternal and paternal height quintile and child stunting was analyzed using a modified Poisson regression approach with robust error variance in consideration of complex survey design with adjustment for covariates. The effect estimates were expressed as relative risks (RRs) with 95% CIs.

Results: A total of 50,372 singleton children were included and the weighted prevalence of stunting was 34.5%. Both maternal height and paternal height were associated with child HAZ (β = 0.047; 95% CI, 0.043, 0.050; and β = 0.022; 95% CI, 0.018, 0.025, respectively). Compared with those born to the tallest mothers and fathers, children from the shortest mothers and the shortest fathers had higher risks of stunting (adjusted RR = 1.89; 95% CI, 1.78, 2.01; adjusted RR = 1.56; 95% CI, 1.47, 1.65, respectively). The mother-offspring associations are substantively larger than the father-offspring associations for each corresponding height quintile. Children from the shortest parents had the highest risk of stunting compared with children from the tallest parents (adjusted RR = 3.23; 95% CI, 2.83, 3.68).

Conclusions: Offspring born to short parents are at increased risk of stunting in LMICs, and this intergenerational effect is partly driven by maternal intrauterine influence. This suggests the importance of improving the nutritional status of children and adults in LMICs, especially female caregivers.

Family size, the physical environment, and socioeconomic effects across the stature distribution

A neglected area in historical stature studies is the relationship between stature and family size. Using robust statistics and a large 19th century data set, this study documents a positive relationship between stature and family size across the stature distribution. The relationship between material inequality and health is the subject of considerable debate, and there was a positive relationship between stature and wealth and an inverse relationship between stature and material inequality. After controlling for family size and wealth variables, the paper reports a positive relationship between the physical environment and stature.

Quantitative trait loci associated with the humoral innate immune response in chickens were confirmed in a cross between Green-Legged Partridgelike and White Leghorn

Natural antibodies (NA) create a crucial barrier at the initial steps of the innate humoral immune response. The main role of NA in the defense system is to bind the pathogens at early stages of infection. Different pathogens are recognized by the presence of highly conserved antigen determinant [e.g., lipopolysaccharide (LPS) in gram-negative bacteria or lipoteichoic acid (LTA) in gram-positive bacteria]. In chickens, a different genetic background of NA binds LPS and LTA antigens, encoded by different QTL. The main objective of this work was to confirm known QTL associated with LPS and LTA NA. For this purpose a chicken reference population was created by crossing 2 breeds: a commercial layer, White Leghorn, and a Polish indigenous chicken, Green-Legged Partridgelike. The chromosomal regions analyzed harbored to GGA3, GGA5, GGA6, GGA8, GGA9, GGA10, GGA14, GGA15, GGA18, and GGAZ. The data collected consisted of the NA titers binding LPS and LTA (determined by ELISA at 12 wk of age) as well as the genotypes (30 short tandem repeat markers; average of 3 markers/chromosome, collected for generations F(0), F(1), and F(2)). The analyses were performed with 3 statistical models (paternal and maternal half-sib, line cross, and linkage analysis and linkage disequilibrium) implemented in GridQTL software (http://www.gridqtl.org.uk/). The QTL study of humoral innate immune response traits resulted in the confirmation of 3 QTL associated with NA titers binding LPS (located on GGA9, GGA18, and GGAZ) and 2 QTL associated with NA titers binding LTA (located on GGA5 and GGA14). A set of candidate genes within the regions of the validated QTL has been proposed.

Wealth, inequality, and insolation effects across the 19th century white US stature distribution

Sources associated with 19th century stature variation have been widely considered. Using US state prison records and robust statistics, this paper illustrates that 19th century US white statures were positively associated with a broad combination of wealth, equality, and environmental characteristics. Individuals from geographic areas characterized by low wealth and high inequality had shorter statures. After controlling for various factors, direct sunlight--the primary source of vitamin D--was also positively associated with stature. After controlling for wealth, inequality, and insolation, farmers were taller than workers in other occupations. These wealth, insolation, and socioeconomic relationships are significant across the stature distribution.

Nineteenth century Mexican statures in the United States and their relationship with insolation and vitamin D

The use of height data to measure living standards is now a well-established method in economics. However, there are still some populations, places and times for which the comparison across groups remains unclear. One example is 19th century Mexicans in the US. This study demonstrates that after comparing the statures of Mexicans born in Mexico and the US the primary source of the stature difference between the two groups was birth year, and the stature gap increased as the US economy developed while the Mexican economy stagnated. Moreover, the stature growth of Mexicans born in the US was related to vitamin D, and the Mexican relationship between stature and insolation was more like that of Europeans than Africans.

Linkage analysis of adult height in a large pedigree from a Dutch genetically isolated population

Despite extensive research of genetic determinants of human adult height, the genes identified up until now allow to predict only a small proportion of the trait's variance. To identify new genes we analyzed 2,486 genotyped and phenotyped individuals in a large pedigree including 23,612 members in 18 generations. The pedigree was derived from a young genetically isolated Dutch population, where genetic heterogeneity is expected to be low and linkage disequilibrium has been shown to be increased. Complex segregation analysis confirmed high heritability of adult height, and suggested mixed model of height inheritance in this population. The estimates of the model parameters obtained from complex segregation analysis were used in parametric linkage analysis, which highlighted three genome-wide significant and additionally at least four suggestive loci involved in height. Significant peaks were located at the chromosomal regions 1p32 (LOD score = 3.35), 2p16 (LOD score = 3.29) and 16q24 (LOD score = 3.94). For the latter region, a strong association signal (FDR q < 0.05) was obtained for 19 SNPs, 17 of them were located in the CDH13 (cadherin 13) gene of which one (rs1035569) explained 1.5% of the total height variance.

Comprehensive multi-stage linkage analyses identify a locus for adult height on chromosome 3p in a healthy Caucasian population

There have been a number of genome-wide linkage studies for adult height in recent years. These studies have yielded few well-replicated loci, and none have been further confirmed by the identification of associated gene variants. The inconsistent results may be attributable to the fact that few studies have combined accurate phenotype measures with informative statistical modelling in healthy populations. We have performed a multi-stage genome-wide linkage analysis for height in 275 adult sibling pairs drawn randomly from the Victorian Family Heart Study (VFHS), a healthy population-based Caucasian cohort. Height was carefully measured in a standardised fashion on regularly calibrated equipment. Following genome-wide identification of a peak Z-score of 3.14 on chromosome 3 at 69 cM, we performed a fine-mapping analysis of this region in an extended sample of 392 two-generation families. We used a number of variance components models that incorporated assortative mating and shared environment effects, and we observed a peak LOD score of approximately 3.5 at 78 cM in four of the five models tested. We also demonstrated that the most prevalent model in the literature gave the worst fit, and the lowest LOD score (2.9) demonstrating the importance of appropriate modelling. The region identified in this study replicates the results of other genome-wide scans of height and bone-related phenotypes, strongly suggesting the presence of a gene important in bone growth on chromosome 3p. Association analyses of relevant candidate genes should identify the genetic variants responsible for the chromosome 3p linkage signal in our population.

Genetics of human growth

Genes involved in human growth consist of major growth genes and minor growth genes. Major growth genes have fundamental effects on human growth, and their mutations cause growth failure (or overgrowth) which are recognizable as single gene disorders. Minor growth genes exert relative minor additive effects on human growth, and their combination is involved in the development of short (or tall) stature as a multifactorial trait. This review summarizes the current knowledge about the major and the minor growth genes, and refers to the recent molecular approach of identification of the growth genes.

Association and haplotype analyses of the COL1A2 and ER-alpha gene polymorphisms with bone size and height in Chinese

Bone size (BS) is another risk factor of fracture independent of BMD in determining bone strength, and height is highly related with BS. To test the effect of the estrogen receptor-alpha (ER-alpha) and collagen type I alpha 2 (COL1A2) genes on the variation of BS and height, we genotyped the PvuII and XbaI polymorphisms in the intron 1 of the ER-alpha gene and the MspI and (GT)n markers in the intron 47 and intron 1 of the COL1A2 gene in 400 Chinese nuclear families with a total of 1256 individuals. The BS at the hip and spine was measured using a Hologic QDR 2000 dual-energy X-ray absorptiometry (DXA) scanner. Population stratification, total-family association, and within-family association were used to test the relationship of BS (at the spine and hip) and height with the four polymorphisms. We also performed these association analyses with the haplotypes of the MspI and (GT)n polymorphisms in the COL1A2 gene, and with the haplotypes of the PvuII and XbaI markers in the ER-alpha gene. Weak within-family association was found between the COL1A2-MspI (P = 0.05) and the femoral neck BS, between the ER-alpha-PX (P = 0.04) and the intertrochanter BS, and between the COL1A2-(GT)(17) (P = 0.02), COL1A2-m(GT)(17) (P = 0.009) and height. Subsequent permutation tests generally confirmed the suggestive within-family association. For the weak within-family association, the proportions of phenotypic variance accounted by the COL1A2-MspI, ER-alpha-PX, COL1A2-(GT)(17), COL1A2-m(GT)(17) markers were 1.50%, 1.51%, 2.15%, and 2.43% for the corresponding phenotypes. The association results indicate that the (GT)n and MspI markers of COL1A2 gene may have some influence on the variation of both BS and height, and the XbaI and PvuII markers of ER-alpha gene may have some effect on the variation of height in Chinese but not on the variation of BS.

Characterization of an X-chromosome PCR-RFLP marker associated with fat deposition and growth in the pig

The X-chromosome, highly conserved within mammals, has been shown to contain major quantitative trait loci (QTL) for growth and fat deposition in the pig. We have discovered a BamHI polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) marker that was assigned to the porcine X-chromosome by two-point and multi-point linkage analysis following genotyping of a three-generation Berkshire by Yorkshire reference family. The marker was positioned 9 cM telomeric to SW2126 and 15.6 cM centromeric to SW1943. Sequence flanking the marker was found to have high similarity to existing database porcine DNA repeat elements. Association analyses of the BamHI marker for growth and meat quality traits in the reference family revealed significant association with marbling (P < 0.03), 10th rib back fat (P < 0.09) and total lipid percentage (P < 0.05), as well as with loin eye area (P < 0.04), average glycolytic potential (P < 0.03) and average lactate content (P < 0.04). Further studies are required to determine the X-chromosome functional gene affecting fat deposition and growth in the pig.