Hypogammaglobulinaemia during pregnancy in identical twin sisters.

The clinical histories and reaction to pregnancy is described in identical twin sisters with acquired hypogammaglobulinemia. Additional evidence for the genetic basis of this disorder is advanced. A possible association with myasthenia gravis is noted and the occurrence of fetal growth retardation is described. Replacement therapy should be given when the diagnosis is made, and high doses might be useful during pregnancy especially if fetal growth retardation seems to be present.