A: Linkage-analysis results for BMI-zadj-PI (358 sibling pairs). Alternating blue and black lines represent Chrs labeled on the x axis, and the strength of linkage is indicated by the LOD score on the y axis. B: Comparison of Chr 1 linkage results for BMI-zadj-PI, BMI-zadj-F508del (219 sibling pairs), and BMI-zadj (402 sibling pairs). C: Comparison of Chr 5 linkage results for each phenotype. Linkage analysis was performed with each residual phenotype by using the variance-components algorithm as implemented in the MERLIN 1.1.2 software program (34). BMI-zadj, BMI-z5to10 values adjusted for female sex, birth cohort, pancreatic insufficiency, and history of meconium ileus; BMI-zadj-F508del, BMI-zadj values with the inclusion of only subjects homozygous for F508del; BMI-zadj-PI, BMI-zadj values with the inclusion of only pancreatic-insufficient subjects; BMI-z5to10, average BMI z score from 5 to 10 y of age; Chr, chromosome; LOD, log of odds; PI, pancreatic insufficiency.