AP BIOLOGY

Detailed explanation-1: -MLL-rearranged ALL (MLL-r-ALL) is characterized by hyperleukocytosis, aggressive behavior with early relapse, relatively high incidence of central nervous system (CNS) involvement, and poor prognosis.

Detailed explanation-2: -The 5-year survival rate for people age 20 and older is 40%. The 5-year survival rate for people under age 20 is 89%. Recent advances in treatment have significantly lengthened the lives of people with ALL. However, survival rates depend on several factors, including biologic features of the disease and a person’s age.

Detailed explanation-3: -While all of the following are prognostic factors, only certain ones are used to determine which risk group a child is in. (The first 2 factors – age at diagnosis and initial white blood cell count – are thought to be the most important.)

Detailed explanation-4: -Similar to B-ALL, the key prognostic determinant in T-ALL is minimal residual disease (MRD) response. Unlike B-ALL, other factors including age, white blood cell count at diagnosis, and genetics of the ALL blasts are not independently prognostic when MRD response is included.