aberrance, aberrancy, aberration, deviance

a state or condition markedly different from the norm

• chromosomal aberration, chromosomal anomaly, chrosomal abnormality, chromosonal disorder — any change in the normal structure or number of chromosomes; often results in physical or mental abnormalities
• deflection, warp — a twist or aberration; especially a perverse or abnormal way of judging or acting

• abnormality, abnormalcy, abnormal condition — an abnormal condition