The present invention relates to provide a protein group binding to keratin which is the major component of body hair, or genes encoding the same, particularly to keratin-associated proteins (KAP) which bind specifically and strongly to hair keratin or genes encoding the same. The base sequence of eurochromtic region of approximately 33.5 Mb of human chromosome 21 was determined, a dot-matrix analysis of the base sequence of the long arm region of chromosome 21 (21q22.3) was carried out, homology search was made to low frequency repetitive sequences and 16 KAP genes being expressed only in hair root cells were found. Moreover, the high frequency repetitive sequences present in the sequence spanning for approximately 1 Mb between CLDN8 gene and TIAM1 gene in the long arm region of chromosome 21(21q22.11) were masked, the presence or absence of short low frequency repetitive sequence was searched, and 22 KAP genes were found. Moreover, a group of functional peptide was designed from the above mentioned KAPs.