THE PREVIOUS reports concerning a large family with hereditary ataxia have dealt in detail with the clinical,1 pathological,2 and genetic features.3 In these studies ages of onset were obtained for 32 of the 45 affected members. The average age at time of onset was 26.5 years; however, the age range of 17 to 35 years (except for one member, between 35 and 40 years of age), was a fortunate aspect, for it enabled us to be reasonably certain that if the disease was to appear it would do so before the age of 35.
Another conclusion which emerged through previous studies was that the disease was caused primarily by a simple dominant gene with complete penetrance. The dominant nature of the ataxia was shown by the appearance of the disease, on the average, in one-half the children in the affected sibships and the failure of the ataxia
SCHUT JW, BÖÖK JA. HEREDITARY ATAXIADifference Between Progeny of Male and Female Affected Members and a Definition of Certain Signs Useful in Detecting the Disease Prior to Onset of Clinical Symptoms. AMA Arch NeurPsych. 1953;70(2):169-179. doi:10.1001/archneurpsyc.1953.02320320035003