title: Population-specific alleles: the polymorphism (K121Q) of the human glycoprotein PC-1 gene is strongly associated with race but not with insulin resistance in black and white children.
abstract: The K121Q polymorphism of the glycoprotein PC-1 gene was recently reported to associate with insulin resistance (IR) in an all-Caucasian, Sicilian population. Given black-white differences in plasma insulin and IR, we compared the prevalence of the KK, KQ, and QQ genotypes and their associations with insulin and IR in 2 large, biracial pediatric samples: 1 hospital-based (n = 301, 137 blacks and 164 whites) and 1 school-based (n = 639, 344 blacks and 295 whites). The Q allele frequencies in the hospital-based and school-based cohorts in black children were 0.80 and 0.77 and in the white children, 0.15 and 0.13. The K allele frequencies in the hospital-based and school-based cohorts in black children were 0.20 and 0.23 and in the white children, 0.85 and 0.87. Differences in allelic frequencies were highly significant (chi square test, P <.0001) for both the hospital-based cohort and the school-based cohort. Both cohorts were in Hardy-Weinberg equilibrium. Within race, after covariance adjusting for age and body mass index (BMI), there were no significant differences (P >/=.10) among the 3 PC-1 genotypes for insulin, glucose, or homeostasis model assessment (HOMA) IR. After covariance adjusting for age and BMI, black girls had higher insulin (P =.0007) and higher HOMA IR (P =.0002) than white girls. The K121Q polymorphism was not associated with insulin, glucose, or HOMA IR measures in black or white children. However, the QQ genotype was population-specific, encompassing most black children versus 1% to 3% of white children. As such, K121Q genotyping should be useful in epidemiology, population genetics, and forensic anthropology.
authors.affiliation: Division of Cardiology, Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Morrison
authors.forename: Ralph
authors.initials: R
authors.lastname: Gruppo
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Glueck
authors.forename: Davis
authors.initials: D
authors.lastname: Stroop
authors.forename: Robert N
authors.initials: RN
authors.lastname: Fontaine
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Kathleen L
authors.initials: KL
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000483:Alleles; D044383:Black People / Q000235:genetics*; D001786:Blood Glucose / Q000378:metabolism; D001827:Body Height; D001835:Body Weight; D002648:Child; D015331:Cohort Studies; D005215:Fasting; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006706:Homeostasis; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D010727:Phosphoric Diester Hydrolases / Q000235:genetics*; D011110:Polymorphism, Genetic; D011755:Pyrophosphatases / Q000235:genetics*; D044465:White People / Q000235:genetics*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D010727:Phosphoric Diester Hydrolases; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1; D011755:Pyrophosphatases