duete; see due, ty 2 ]. syn: duty, obligation refer to something a person feels bound to do. A duty often applies to what a person performs in fulfillment of the permanent dictates of conscience, piety, right, or law: one's duty to tell the truth; a parent's duty to raise children properly.
Mutations in the RB1 gene are responsible for most cases of retinoblastoma. RB1 is a tumor suppressor gene, which means that it normally regulates cell growth and keeps cells from dividing too rapidly or in an uncontrolled way.
Retinoblastoma is a rare cancer of the retina, the thin membrane on the inside back of the eye that is stimulated by light. Retinoblastoma is usually diagnosed before a child reaches the age of 3. Retinoblastoma can be hereditary (passed down in families) or non-hereditary.