Age-specific expression patterns of five proteins of interest selected for discussion. Expression patterns for five proteins with the largest age-specific changes in expression. A, Hemoglobin subunit gamma-1 (HBG1); B, Hemoglobin subunit gamma-2 (HBG2); C, collagen alpha-1I chain (CO1A1); D, Ig alpha-1 chain C region (IGHA1) and E, Ig alpha-2 chain C region (IGHA2).