Background：

RFPL4A is a 287 amino acid protein. RFPL4A contains a cysteine-rich RING finger-like region (C3YC4)， a coiled-coil motif， and B30.2 domains characteristic of the RING-B30 family of E3 ubiquitin-protein ligases， such as MID1. The RFPL4A gene maps to human chromosome 19q13.42. Chromosome 19 consists of approximately 63 million bases and makes up over 2% of human genomic DNA. Chromosome 19 includes a diversity of interesting genes and is recognized for having the greatest gene density of the human chromosomes. It is the genetic home for a number of immunoglobulin superfamily members including the killer cell and leukocyte Ig-like receptors， a number of ICAMs， the CEACAM and PSG families， and Fc?receptors. Key genes for eye color and hair color also map to chromosome 19. Peutz-Jeghers syndrome， spinocerebellar ataxia type 6， the stroke disorder CADASIL， hypercholesterolemia and insulin-dependent diabetes have been linked to chromosome 19.