Relationship of the Human Growth Hormone Receptor Exon 3 Genotype with Final Adult Height and Bone Mineral Density

Abstract

Three recent clinical studies have reported that two of the most common isoforms of the human GH (hGH) receptor (hGHR), exon 3 full-length (3+) and exon 3 deleted (3-), may have differential effects on the growth response of children receiving hGH therapy, whereas others refute this. However, none of the investigations has explored the relationship between these hGHR isoforms and final adult height (FAH) or measures of bone mineral density (BMD) within a healthy adult population. The aim of this study was to investigate the possible influences of hGHR exon 3 isoforms on FAH and BMD measures of a normal population. The study was designed to correlate the hGHR exon 3 genotype of a cohort of healthy adults with FAH, BMDs [spine (L2-L4) and hip (femoral neck)], and quantitative ultrasound (QUS) of the heel. Participants were 368 unrelated healthy adult white women, aged 18-35 yr. We analyzed association of hGHR exon 3 genotypes with FAH, BMD, and QUS. Heights were measured using a stadiometer, BMDs using dual-energy x-ray absorptiometry, and QUS by standard technique. Detailed medical histories, including lifestyle factors, were obtained using a standardized interview. The distribution of hGHR genotypes in the 368 samples was 53.3% for 3+/3+, 35.6% for 3+/3-, and 11.1% for 3-/3-. There was no correlation between the hGHR exon 3 genotypes and FAH, BMD, or QUS in this cohort. The hGHR 3+ and 3- isoforms appear not to have differential effects on two major growth outcomes of hGH action, FAH, and BMD in a population of healthy adult women.