Congenital aplasia of parathyroid glands and thymus.

Congenital absence of the parathyroid glands may be associated with congenital absence of the thymus (Lobdell, 1959). This is not surprising as both structures arise together from the 3rd and 4th branchial pouches. In the same way, vascular anomalies of the 3rd and 4th branchial arteries are found to be associated with abnormalities of the thymus, including thymic aplasia (Cameron, 1965). A patient is described in whom thymic aplasia, absence of the parathyroid glands, and congenital heart disease were present. The interest of this case lies in the light this 'experiment of nature' may shed on the immunological systems of the body.