Application of the major gene index and offspring-between-parents function to dermatoglyphic fingertip variables.

Forty-eight digital dermatoglyphic variables in 192 nuclear families were analyzed to search for evidence of major gene effects, utilizing a pair of recently developed statistics called the major gene index (MGI) and offspring-between-parents (OBP) function. They operate on the principle that under a multifactorial blending inheritance scheme an offspring's phenotypic value approximates the midparental value, whereas under major gene inheritance, the child's value more closely resembles that of one of his parents. Both statistics yielded comparable results. All ridge-count variables showed no strong deviation from a multifactorial model. Pattern-type variables gave values suggesting the presence of major gene effects, but these results were probably the consequence of the variables' relatively discrete distributions, since a departure of a variable from a reasonably continuous phenotypic distribution was shown to interfere significantly with the interpretation of both statistics.