Thus, in case the individuals with GS phenotype (when excluding other reasons of unconjugated hyperbilirubinemia except genetic ones) have the significant increase in total/unconjugated bilirubin concentration or/and in genotype 6TA/6TA, 6TA/7TA rs3064744 — it is reasonable to perform a research to search for the carriership of rare alleles of rs1799945 (H63D), rs1800562 (C282Y), rs1800730 (S65C) variants of HFE gene, rs113993960 (ΔF508) variants of CFTR gene, rs28929474 (PIZ), rs17580 (PIS) variants of SERPINA1 gene. Here, CFTR is linked to Hyperbilirubinemia.