Familial resemblance for immunoglobulin levels.

The familial resemblance for immunoglobulin A, D, E, G, and M levels was investigated with family data collected in Canada and the U.S., entertaining both multifactorial and single gene hypotheses. Significant familial effects were found for each of the immunoglobulins, and there was significant support for a major gene hypothesis for IgA and IgD levels. Whereas there have been several reports suggesting a major gene determinant for IgE levels, including that from our own Canadian study, analysis of the U.S. sample suggested that a multifactorial component parsimoniously explained the observed familial resemblance.