The invention relates to nucleic acids encoding a mammalian ABCA5 gene, and proteins encoded thereby, whose expression is increased in certain diseases, disorders, or conditions, including, but not limited to, PIN. Further, the invention relates to diagnostic assays for identifying the DNA-binding protein ABCA5 (also known as PIN-1). The invention also relates to oligonucleotide sequence(s) or antibodies that specifically bind with ABCA5 or variants thereof.