Table 2: A 4th Categorary for McKusick’s Catalogue of Mendelian Inheritance in Man [23].

(1) Dominant. Presence of the gene causes disease.

(2) Recessive. Absence of the gene causes disease.

(3) X-linked. Sex-linked, gene on X chromosome.

(4) Autoimmune. Multiple co-dominant genes (V genes and H genes) with incomplete penetrance, due to need for antigenic triggers and somatic gene mutations in lymphocytes [40, 41].