What is the nature of paroxysmal nocturnal hemoglobinuria (PNH)?

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized as a rare acquired stem cell disorder. This condition arises due to a mutation in the PIGA gene within hematopoietic stem cells, which leads to the inability of blood cells to express certain proteins that protect them from being destroyed by the immune system. Because it is an acquired disorder, it is not passed from parent to offspring through genetic inheritance like some other hematological conditions.

The fact that PNH occurs due to a mutation acquired later in life, instead of being inherited through genetic lines, underscores its classification as an acquired disorder. This mutation causes a unique set of symptoms, including intermittent hemolysis (destruction of red blood cells), and can lead to complications such as thrombosis and bone marrow failure. The nuances seen in patients with PNH, such as the episodic nature of hemolysis often emphasized during the night, are further indicative of its acquired status rather than an inherited one.

The other classifications involving sex-linked, autosomal dominant, or autosomal recessive inheritance patterns imply a genetic transmission from parents to offspring, which does not apply to PNH. Instead, its development is linked to somatic mutations that occur during an individual's lifetime.