Genesis of a fact: Friedreich ataxia as a recessive disorder

Abstract

Fleck and Kuhn suggested that scientific “facts” are constructed by a professional community instead of being discovered. This is examined using recessive inheritance for Friedreich Ataxia (FA). Sibling recurrences were known early on, but, for well over half a century, it was described as hereditary, which meant transmitted from generation to generation. Several factors were involved. First, FA is extremely variable, and overlaps with other disorders, making it seem like part of a spectrum, instead of a distinct unit trait suited to Mendelian analysis. Second, a medical system for inheritance based on a hereditary force for constancy with effects throughout life had overlapping doctrines central to analyses: Blastophoria (toxic damage to inheritance), Degeneration, Neuropathic Inheritance, and Polymorphism (several forms with one cause). Different factors could weaken the force, predisposing to a wide range of problems in the next generation, making it hereditary. Manifestations depended on interactions with other factors, and could vary widely, but the nervous system was especially vulnerable. These concepts were incompatible with the Mendelian inheritance of a specific, stable gene linked to a unique phenotype. Changes in medical experience let physicians deconstruct older “facts” about FA, making it a recessive at long last