Medical Genetics A congenital immunodeficiency characterized pathologically by absence or hypoplasia of the thymus and parathyroid glands and mmunologically by partial or complete T-cell immunodeficiency but normal or near -normal B-cell immunityMedical Genetics A congenital immunodeficiency characterized pathologically by absence or hypoplasia of the thymus and parathyroid glands and immunologically by partial or complete T-cell immunodeficiency but normal or near-normal B-cell immunity