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Table 1 Characteristics of Normative Aging Study participants, 1961-2001, with measurements on three phenotypes.

From: Folate network genetic variation, plasma homocysteine, and global genomic methylation content: a genetic association study

  Plasma homocysteinea Global genomic DNA methylation (Alu elements)b Global genomic DNA methylation (LINE-1 elements)b
  N = 760 N = 628 N = 621
Age at phenotype measurement 68.6 (7.3)* 72.5 (6.8) 72.5 (6.8)
Education - college graduate or higher (%) 26.8 28.6 28.7
White (%) 100 100 100
Baseline BMI (kg/m2) 25.9 (2.9) 25.9 (2.9) 25.9 (2.9)
Cigarette smokingc    
   Current (%) 6.7 5.4 5.5
   Former (%) 63.0 63.4 63.5
   Never (%) 30.3 31.2 31.1
Alcohol intake (% consuming ≥ 2 drinks/day) 12.4 13.7 13.5
Baseline diabetes diagnosis (%) 0.13 0.16 0.16
Baseline systolic blood pressure (mm Hg) 122.1 (12.7) 121.7 (12.5) 121.6 (12.6)
MTHFR 677 C>T (rs1801133) TT genotype (%) 12.2 12.3 12.6
Plasma folate (ng/ml)d 10.4 (5.7) 17.2 (15.1) 17.0 (14.9)
Plasma vitamin B-6 (pmol/ml) 84.9 (85.3) 104.6 (96.1) 104.8 (96.7)
Plasma vitamin B-12 (pg/ml) 458.9 (190.6) 512.8 (371.2) 514.9 (373.8)
Plasma total homocysteine (nmol/ml) 10.6 (3.7) 11.0 (4.2) 10.9 (4.2)
Global DNA methylation in Alu elements (%)   26.3 (1.1)  
Global DNA methylation in LINE elements (%)    76.9 (1.9)
  1. *mean (standard deviation) unless otherwise indicated
  2. aN for homocysteine group ranges from 730 to 760 for variables in table.
  3. bMen in the two global genomic methylation groups were very similar, and dates of marker collection were nearly identical. N for Alu group ranges from 618 to 628, and N for LINE-1 group ranges from 611 to 621.
  4. cSmoking status was assessed using most recent data prior to phenotype measurement.
  5. dHomocysteine and corresponding plasma folate, vitamin B-6, and vitamin B-12 data were collected prior to the initiation of folate fortification; global genomic methylation markers, and corresponding plasma nutrient markers were measured post-folate fortification, in a later time period.