Growth hormone pharmacogenetics: the interactive effect of a microsatellite in the IGF1 promoter region with the GHR-exon 3 and -202 A/C IGFBP3 variants on treatment outcomes of children with severe GH deficiency.
ABSTRACT Insulin-like growth factor type 1 (IGF1) is a mediator of growth hormone (GH) action, and therefore, IGF1 is a candidate gene for recombinant human GH (rhGH) pharmacogenetics. Lower serum IGF1 levels were found in adults homozygous for 19 cytosine-adenosine (CA) repeats in the IGF1 promoter. The aim of this study was to evaluate the influence of (CA)n IGF1 polymorphism, alone or in combination with GH receptor (GHR)-exon 3 and -202 A/C insulin-like growth factor binding protein-3 (IGFBP3) polymorphisms, on the growth response to rhGH therapy in GH-deficient (GHD) patients. Eighty-four severe GHD patients were genotyped for (CA)n IGF1, -202 A/C IGFBP3 and GHR-exon 3 polymorphisms. Multiple linear regressions were performed to estimate the effect of each genotype, after adjustment for other influential factors. We assessed the influence of genotypes on the first year growth velocity (1st y GV) (n=84) and adult height standard deviation score (SDS) adjusted for target-height SDS (AH-TH SDS) after rhGH therapy (n=37). Homozygosity for the IGF1 19CA repeat allele was negatively correlated with 1st y GV (P=0.03) and AH-TH SDS (P=0.002) in multiple linear regression analysis. In conjunction with clinical factors, IGF1 and IGFBP3 genotypes explain 29% of the 1st y GV variability, whereas IGF1 and GHR polymorphisms explain 59% of final height-target-height SDS variability. We conclude that homozygosity for IGF1 (CA)19 allele is associated with less favorable short- and long-term growth outcomes after rhGH treatment in patients with severe GHD. Furthermore, this polymorphism exhibits a non-additive interaction with -202 A/C IGFBP3 genotype on the 1st y GV and with GHR-exon 3 genotype on adult height.
- SourceAvailable from: Claus Højbjerg Gravholt[show abstract] [hide abstract]
ABSTRACT: Data on incidence rates are scarce in GH deficiency (GHD). Here, we estimate the incidence rate in childhood onset (CO) and adult onset (AO) GHD in Denmark. We used three national registries to identify 9131 cases with an increased risk of GHD. Date of entry was defined using the date when a registration had taken place and when a date of sufficient information could be defined from a thorough examination of a record of a GHD patient, which ever came last. We considered date of entry as the incident date. Sex-specific incidence rates of GHD in children and adults using the background population as reference. During 1980-1999, 1823 patients were incident. Three-hundred and three males and 191 females had CO, 744 males and 585 females had AO GHD. The incidence rate over time was stable for females with AO GHD and increasing for the other three subgroups. Average incidence rate for CO males, 2.58 (95% confidence interval (CI), 2.30-2.88), CO females, 1.70 (95% CI, 1.48-1.96), AO males, 1.90 (95% CI, 1.77-2.04), and AO females, 1.42 (95% CI, 1.31-1.54) all per 100 000. The incidence rate was significantly higher in males compared to females in the CO GHD group (P < 0.001) and in the AO GHD group in the age ranges of 45-64 and 65+years (P < 0.001). There was no significant difference in the 18-44 years age group. In conclusion, we have identified the incidence rates of GHD in a nationwide study of Denmark. In this population-based study, we have identified in CO GHD and in the two oldest age groups of AO GHD, a statistically significant higher incidence rate in males when compared with females.European Journal of Endocrinology 08/2006; 155(1):61-71. · 3.14 Impact Factor
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ABSTRACT: Stature (adult height) is one of the most heritable human traits, yet few genes, if any, have been convincingly associated with adult height variation in the general population. Here, we selected 150 tag SNPs from eight candidate genes in the growth hormone (GH)/insulin-like growth factor-1 (IGF1) axis (GHR, GHRH, GHRHR, IGF1, IGFALS, IGFBP3, JAK2, STAT5B), and genotyped them in approximately 2,200 individuals ascertained for short or tall stature. Nominally significant tag SNPs were then tested in three additional replication cohorts, including a family-based panel to rule out spurious associations owing to population stratification. Across the four height cohorts (N = 6,075 individuals), we did not observe any consistent associations between stature and common variants (> or =5% minor allele frequency) in these eight genes, including a common deletion of the growth hormone receptor gene exon 3. Tests of epistatic interactions between these genes did not yield any results beyond those expected by chance. Although we have not tested all genes in the GH/IGF1 axis, our results indicate that common variation in these GH/IGF1 axis genes is not a major determinant of stature, and suggest that if common variation contributes to adult height variation in the general population, the variants are in other, possibly unanticipated genes.Human Genetics 10/2007; 122(2):129-39. · 4.63 Impact Factor
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ABSTRACT: In humans, growth hormone receptor (GHR) transcripts exist in two isoforms differing by the retention (GHRfl) or exclusion (GHRd3) of exon 3, whereas in mice GHRfl is solely expressed. This species-specific expression pattern is believed to result from an alternative splice event that, on the basis of conflicting data obtained in humans, has been considered to be tissue-, developmentally, and/or individual-specific. To decipher the molecular basis of this unusual trait, we isolated a 6.8-kilobase fragment spanning exon 3 from individuals expressing GHRfl. Sequence analysis revealed the existence of two 99% identical retroelements flanking this exon. Unexpectedly, individuals expressing GHRd3 displayed a 2.7-kilobase deletion involving exon 3, which most likely results from an ancestral homologous recombination between the two retroelements. The lineage of these retroelements during primate evolution revealed the species specificity of the GHRd3 allele. These findings led us to propose a model underlying the existence of the sole GHRfl allele in most species. Such a retrovirus-mediated alternative splice mimicry, which clears up several as yet unexplained phenomena (i.e. the above-mentioned expression data, the Mendelian inheritance of GHR expression patterns, and the deletion of nonconsecutive exons in growth hormone resistant patients), represents a novel physiological mechanism accounting for protein diversity between and within species.Journal of Biological Chemistry 07/2000; 275(25):18664-9. · 4.65 Impact Factor