The Louisville Twin Study: Past, Present and Future

The Louisville Twin Study (LTS) is nationally recognized as one of the largest and most comprehensive studies of child development related to multiple birth status. The LTS is unique because of the extensive longitudinal face-to-face assessments, the frequency of data collection, the inclusion of data on additional family members (i.e., parents, siblings, grandparents; and later, twins’ own spouses and children), and the variety of data collection methods used. Data preservation efforts began in 2008 and are largely complete, although efforts are ongoing to obtain funding to convert the electronic data to a newer format. A pilot study was completed in the summer of 2018 to bring the twins, who are now middle-aged, back for testing. A grant is currently under review to extend the pilot study to include all former participants who are now ≥40 years of age. Opportunities for collaboration are welcome.

Blood Glutathione and Cysteine Concentrations in Twin Children

Glutathione and cysteine are major antioxidants in blood that are associated with health and longevity. To ensure their measurement, careful attention to avoid auto-oxidation is necessary to stabilize the samples. Since no report of these compounds has been reported in children, our goal was to determine their levels of reduced and oxidized glutathione (GSH and GSSG) and cysteine (Cys and CSSC), To this end, 140 healthy children, ages 2 to 9 years from the Louisville Twin Study were studied. Blood samples were collected and analyzed for GSH, GSSG, Cys, and CSSC by our HPLC dual electrochemical method. The results showed that GSH and total GSH (GSH + GSSG) levels for monozygotic (MZ) twins were significantly higher (P < 0.001) than levels for dizygotic (DZ) twins. However, the opposite occurred for Cys and total Cys (Cys + CSSC) in that the levels were significantly higher for DZ twins than for MZ twins. (P < 0.005-0.013). In spite of this marked difference in zygosity, the withinpair correlations for twin pairs used for estimating heritability suggested that there was a major environmental influence for total GSH and total Cys. Finally. GSH levels were significantly lower for young (2–9 years) children than adults (P < 0.001).