HEREDITARY ABNORMALITY OF LUTEINIZING-HORMONE RESULTING IN DISCREPANTSERUM CONCENTRATIONS DETERMINED BY DIFFERENT ASSAYS

We herein report familial defects in the molecular structure of lutein izing hormone (LH). The propositus was a 29-year-old woman with repeat ed abortion in whom the serum LH concentration was extremely low deter mined by an immunoradiometric assay utilizing two monoclonal antibodie s for the intact LH dimer and beta-subunit of LH (SPAC-S kit). Further studies on the serum LH concentration in this propositus by five diff erent assay systems gave various results ranging from low to normal va lues. Bioassay of the propositus's LH using C57 black mice showed norm al in biological activity. These data suggest that LH in the propositu s is abnormal in terms of its molecular structure located in the bond region between alpha and beta subunits. A family study showed that the bioactivity of LH was normal in all family members. The serum LH was not detected in either the propositus or her brother with the SPAC-S k it even after the administration of LHRH, while the serum LH concentra tions in the father, mother and sister were approximately half the nor mal range, indicating that the defect is hereditary and the mode of in heritance is autosomal dominant: the propositus and brother were homoz ygously affected, and the parents and sister heterozygously affected.