Whole chromosome monosomy,nonmosaic (meiotic nondisjunction)

This code signifies a genetic condition characterized by the complete absence of one chromosome from a pair in all cells of the body, resulting from an error during meiosis. This nonmosaic state means the chromosomal abnormality is present uniformly throughout the individual's tissues, typically leading to significant developmental and health challenges.

Assign this code when diagnostic testing, such as karyotyping or chromosomal microarray analysis, confirms a whole chromosome monosomy that is nonmosaic. This typically applies to conditions like Turner syndrome (monosomy X) or other rare, usually lethal, autosomal monosomies identified prenatally or postnatally. Documentation should explicitly state "whole chromosome monosomy" and confirm its nonmosaic nature.

• Ensure documentation specifies "nonmosaicism" to differentiate from mosaic forms of monosomy.
• Do not use this code for partial monosomies or deletions; these have distinct codes.
• Always sequence this code as a primary diagnosis when it is the underlying cause of the patient's condition.