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garfyld
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Previously I thought actractiveness comes from only good oral posture but it's actually not true.
Sagittal jaw growth is influenced during puberty by a ratio of androgens and estrogens. The CYP19A1 (formerly CYP19) gene encodes the cytochrome P450 enzyme aromatase (estrogen synthetase), which converts testosterone to estrogen. Genetic variations including single nucleotide polymorphisms might regulate CYP19A1 gene expression or the function of the aromatase protein and thus influence sagittal jaw growth.
Two single nucleotide polymorphisms were significantly associated with average differences in annual sagittal jaw growth in boys. Haplotype analysis demonstrated that haplotypes Trs2470144Trs2445761 and Crs2470144Trs2445761 had significant effects on annual sagittal maxillary growth and on mandibular growth in boys. No association was found in girls.
Growth and development of the maxilla and mandible are determined by genetic and environmental factors.1 Identification of these factors and mechanisms would help diagnosis, prediction, and treatment for skeletal variations. Single nucleotide polymorphisms and the haplotypes defined by common single nucleotide polymorphisms can be genotyped to determine normal and variable craniofacial phenotypes.2 Studies have found that single nucleotide polymorphisms (P561T, C422F, and I526L) in the growth hormone receptor gene are associated with mandibular ramus height in Japanese, Korean, and Chinese populations, and the P561T polymorphism has an inhibitory effect on mandibular growth in young children.3–7 Several single nucleotide polymorphisms have been found to be involved in mandibular prognathism.8–10 A polymorphism of the noggin gene (SNP rs1348322) was present in 4 families with mandibular micrognathia.11
Single nucleotide polymorphism association analysis (Table III) showed that boys with the rs2470144 genotype CC had significantly smaller average annual maxilla growth than those with genotypes CT and TT. For the mandible, the boys with the CC genotype had the smallest amount of average growth, and the boys with TT had the greatest average growth (Table III; Fig 2, A). Boys with rs2445761 genotypes CC and CT had significantly smaller average annual maxilla growth than those with genotype TT, and boys with genotype CC had the smallest average mandibular growth amount, and those carrying TT had the greatest (Table III; Fig 2, B). No significant difference was found in genotypic groups in the girls (Table III; Fig 2, A and B). Linear regression for the different genotypes is presented in Figure 3.
Studies showing estrogen receptors in areas of the jaws including the condyles and palate support the importance of estrogen for jaw mass and growth.16–19 Aromatase (estrogen synthetase) catalyzes the final and rate-limiting step in the conversion of C19 androgens (androstenedione and testosterone) to C18 estrogens (estrone and estradiol); this makes it a key enzyme for estrogen biosynthesis in vivo.20 The CYP19A1 gene is about 123 kb in length, is located at chromosome 15q21.2, and encodes aromatase
Estrogen and testosterone affect many physical features, including facial ones. Estrogen not only initiates pubertal growth in both sexes, but also limits longitudinal bone growth by progressively inducing closure of the epiphyseal growth plate at the end of puberty.12,20 Low doses of estrogen stimulate the pubertal growth spurt and prolong puberty, whereas higher concentrations might inhibit linear growth and promote growth plate closure.20 The biphasic effect of estrogen in both sexes is in contrast with the longitudinal growth-stimulating effect of androgens in boys.37 Clinical data to support the effect of the inhibition of estrogen activity and an increase in the effective testosterone-to-estrogen ratio come from the administration of aromatase inhibitors, resulting in an increased final height in growing boys with short stature.38,39 There is also evidence that, in pubertal boys, a high testosterone-estrogen ratio is supposed to facilitate the growth of cheekbones, mandible, chin, and bones of the eyebrow ridges, and the lengthening of the lower face.26,40
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