Background：

ANGEL2 is a 544 amino acid protein that belongs to the CCR4/nocturin family and exists as two alternatively spliced isoforms. The CCR4 family of proteins are 3′–5′-deadenylases that function in the first step of the degradation of poly(A) mRNA. The CCR4 family most likely displays both RNA and ssDNA substrate preferences， thereby implicating a potential role in many regulatory processes. The ANGEL2 gene maps to human chromosome 1 (1q32.3)， which is the largest human chromosome spanning about 260 million base pairs and making up 8% of the human genome. Chromosome 1 contains about 3，000 genes， and considering the great number of genes there are also a large number of diseases associated with it. The MUTYH gene is located on chromosome 1 and is partially responsible for familial adenomatous polyposis. Stickler syndrome， Parkinsons disease， Gaucher disease and Usher syndrome are also associated with chromosome 1.