Branched-chain amino acids and type 2 diabetes: a bidirectional Mendelian randomization analysis.

OBJECTIVE: Genetic studies have suggested that the branched-chain amino acids (BCAAs) valine, leucine, and isoleucine have a causal association with type 2 diabetes (T2D). However, inferences are based on a limited number of genetic loci associated with BCAAs. METHODS: Instrumental variables (IVs) for each BCAA were constructed and validated using large well-powered data sets and their association with T2D was tested using a two-sample inverse-variance weighted Mendelian randomization approach. Sensitivity analyses were performed to ensure the accuracy of the findings. A reverse association was assessed using instrumental variables for T2D. RESULTS: Estimated effect sizes between BCAA IVs and T2D, excluding outliers, were as follows: valine (ß = 0.14 change in log-odds per SD change in valine, 95% CI: -0.06 to 0.33, p = 0.17), leucine (ß = 0.15, 95% CI: -0.02 to 0.32, p = 0.09), and isoleucine (ß = 0.13, 95% CI: -0.08 to 0.34, p = 0.24). In contrast, T2D IVs were positively associated with each BCAA, i.e., valine (ß = 0.08 per SD change in levels per log-odds change in T2D, 95% CI: 0.05 to 0.10, p = 1.8 × 10-9 ), leucine (ß = 0.06, 95% CI: 0.04 to 0.09, p = 4.5 × 10-8 ), and isoleucine (ß = 0.06, 95% CI: 0.04 to 0.08, p = 2.8 × 10-8 ). CONCLUSIONS: These data suggest that the BCAAs are not mediators of T2D risk but are biomarkers of diabetes.

Frequency of benign neutropenia among Black versus White individuals undergoing a bone marrow assessment.

Healthy individuals in the United States identified as having Black race have lower neutrophil counts, on average, than individuals identified as having White race, which could result in more negative diagnostic evaluations for neutropenia. To test this hypothesis, the proportion of evaluations where the final diagnosis was clinically insignificant neutropenia for Black and White individuals who underwent an evaluation by a haematologist that included a bone marrow (BM) biopsy to investigate neutropenia was assessed. 172 individuals without prior haematological diagnoses who underwent a haematological evaluation to investigate neutropenia. Individuals diagnosed with clinically insignificant neutropenia between Black and White individuals were compared using a propensity-score-adjusted logistic regression. Of 172 individuals, 42 (24%) were classified as Black race, 86 (50%) were males, and the 79 (46%) were over 18 years old. A BM biopsy did not identify pathology in 95% (40 of 42) of Black individuals and 68% (89 of 130) of White Individuals. Black individuals (25 of 42 [60%]) received a final diagnosis of clinically insignificant neutropenia, compared to White individuals (12 of 130 [9%]) (adjusted odds ratio =7.9, 95% CI: 3.1 - 21.1). We conclude that black individuals were more likely to receive a diagnosis of clinically insignificant neutropenia after haematological assessment.