Detection of Pyruvate Dehydrogenase E1α-subunit Deficiencies in Females by Immunohistochemical Demonstration of Mosaicism in Cultured Fibroblasts

Abstract

Deficiency of the E1α-subunit of the pyruvate dehydrogenase (PDH) complex is an X-linked inborn error of metabolism and one of the major causes of lactic acidosis in children. Although most heterozygous females manifest symptoms of the disease, it is often difficult to establish the diagnosis as results based on measurement of total PDH activity, and E1α-immunoreactive protein in patient fibroblasts may be ambiguous because of the variability in the pattern of X chromosome inactivation. We report the development of a set of monoclonal antibodies (MAbs) specific to four subunits of the PDH complex that can be used for detection of PDH E1α deficiency. We also show that anti-E1α and anti-E2 MAbs, when used in immunocytochemical analysis, can detect mosaicism in cell cultures from female patients in which as few as 2–5% of cells express the deficiency. This immunocytochemical approach, which is fast, reliable, and quantitative, will be particularly useful in identifying females with PDH E1α-subunit deficiency as a precursor to mutation analysis.