Zinc finger and BTB domain containing 48 (ZBTB48), also known as telomeric zinc-finger associated protein (TZAP), is a protein that directly binds to the double-stranded repeat sequence of telomeres. In humans it is encoded by the ZBTB48 gene. ZBTB48, also named as TZAP and HKR3, is a 688 amino acid protein, which contains 1 BTB (POZ) domain and 11 C2H2-type zinc fingers and belongs to the krueppel C2H2-type zinc-finger protein family. ZBTB48 is detected in adrenal gland and neuroblastoma. ZBTB48 binds to and regulates the J and/or S elements in MHC II promoter. Zinc finger and BTB domain containing 48 (ZBTB48), also known as telomeric zinc-finger associated protein (TZAP), is a protein that triggers the trimming of telomeres in the absence of shelterin. ZBTB48, is a relatively uncharacterized POK family protein with a POZ-domain and 11 zinc finger domains. ZBTB48, is ubiquitously expressed in human tissues. The ZBTB48 gene is mapped to human chromosome 1p36, which is commonly rearranged (leiomyoma and leukemias) or deleted in various cancers (neuroblastoma, melanoma, Merkel cell carcinomas, pheochromocytoma and breast and colon carcinomas. A correlation between deletions or rearrangements of HKR3 and human cancer suggest a role for ZBTB48 as a potential tumor suppressor.