Polypeptide comprising a sequence having at least 90% of identity with all or part of the sequence comprising a fully defined 732 amino acids (SEQ ID No. 1) sequences given in the specification, for therapeutic use to treat or prevent early canities in humans, is new, where the part comprises at least 30 amino acids. Independent claims are included for: (1) a molecule comprising a sequence of RNA interference (RNAi) having at least 90% of identity with all or part of the sequence comprising SEQ ID No. 2 (having a fully defined 2405 base pairs given in the specification) for therapeutic use in treating or preventing early canities in humans, where the part comprises at least 18 nucleotides； (2) a process for screening molecules modulating the expression of gene encoding for BNIPXL-beta, to identify an agent for cosmetic or therapeutic purposes in the field of pigmentation of integuments, preferably hair, comprising placing the molecule to be tested and gene encoding BNIPXL-beta, under conditions allowing the expression of the gene in the absence of the molecule to be tested, and detecting a change in the level of expression of the gene, in the presence of the molecule to be tested； (3) a process for screening of molecules modulating the activity of BNIPXL-beta polypeptide, to identify an agent for cosmetic or therapeutic purposes, comprising placing molecule to be tested and BNIPXL-beta polypeptide, under conditions allowing highlight of the activity of the polypeptide in the absence of the molecule to be tested, and detecting a change in the activity of the polypeptide due to the presence of the molecule to be tested； (4) a process for diagnosing a tendency towards early canities in an individual, comprising determination of expression level of BNIPXL-beta transcript from a body sample from an individual, and comparing to a reference level； and (5) a process for screening molecules modulating the interaction between BNIPXL-beta polypeptide and polypeptide derived fr
