THE term "heredofamilial" should be applied only to those diseases which are due to a change in the chromosomes which persists for several generations. They may also be called heredodegenerative (Jendrassik1), since they all represent a minus variant. Unlike these persisting changes of the chromosomes, the mutations, which cause heredofamilial diseases, the paravariations, originating under the influence of the surroundings, and the mixovariations, changes due to the union of two genes of different character, are not hereditary.
The properties of a man that are due to the structure of the idioplasm are called constitutional (genotypical, idiotypical). In addition to these inherited properties, there are others acquired in fetal life or after the birth; they were termed "conditional" by Tandler.2 The phenotypical man thus represents a combination of constitutional and conditional factors. A factor of either type may lead to disease when it deviates from the norm. When the
MARBURG O. HEREDITARY SCLEROSES. Arch NeurPsych. 1946;55(4):338–352. doi:10.1001/archneurpsyc.1946.02300150042003
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