Daily Endocrinology Research Analysis
Analyzed 110 papers and selected 3 impactful papers.
Summary
Three impactful endocrinology studies stood out today: a methodological advance showing adaptive sampling long-read sequencing with a custom pipeline (NanoCAH) enables accurate, phased CYP21A2 genotyping for congenital adrenal hyperplasia; a target trial emulation in older adults with diabetic kidney disease indicating SGLT2 inhibitors halve all-cause mortality versus DPP-4 inhibitors; and evidence that HbA1c fails to detect abnormal glucose tolerance in individuals with G6PD deficiency, underscoring diagnostic inequities.
Research Themes
- Genomic diagnostics and methodology in endocrinology
- Diabetes therapeutics and outcomes in older adults with kidney disease
- Diagnostic equity and biomarker performance in diverse populations
Selected Articles
1. Genetic diagnosis of CYP21A2-related CAH: adaptive sampling long-read sequencing is an accurate and scalable solution.
Using adaptive sampling long-read sequencing focused on chromosome 6 and a custom mapper (NanoCAH), the authors achieved accurate detection and phasing of CYP21A2 variants in 34 clinically diagnosed CAH patients, confirming diagnosis in 94% and resolving complex events (chimeras, deletions) missed by standard PCR/MLPA workflows. The approach enabled haplotype phasing without parental samples and proved faster and more scalable than current methods.
Impact: This study provides a practical, scalable solution to a longstanding diagnostic bottleneck caused by CYP21A2/CYP21A1P homology, enabling accurate variant detection and phasing that can directly improve CAH diagnostic workflows.
Clinical Implications: Clinical genetics labs can adopt AS-LRS with a tailored pipeline to replace or complement PCR/MLPA for CYP21A2 testing, improving detection of complex structural variants and providing phasing information that informs genotype–phenotype correlations and counseling.
Key Findings
- AS-LRS plus NanoCAH confirmed CYP21A2-associated CAH in 32/34 patients (94%).
- Reliable haplotype phasing of variants was achieved without parental samples.
- Complex events (e.g., chimeric genes, deletions, missed variants by standard methods) were resolved.
- Method outperformed PCR/MLPA in accuracy and scalability for the CYP21A2 region.
Methodological Strengths
- Adaptive sampling long-read sequencing targeted to chromosome 6 enabling comprehensive coverage.
- Custom bioinformatic tool (NanoCAH) accurately discriminating CYP21A2 vs CYP21A1P reads and enabling phasing.
Limitations
- Single-technology validation in a relatively small cohort (n=34) may limit generalizability across laboratories.
- Clinical utility (e.g., impact on management) was not prospectively evaluated.
Future Directions: Multi-center clinical validation, cost-effectiveness analyses, and extension of the pipeline to other homologous gene–pseudogene systems could accelerate broader adoption in endocrine genetics.
Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder, commonly caused by variants in CYP21A2 (chr6p21.33), which encodes the 21-hydroxylase enzyme. Genetic diagnosis is challenging due to the high homology between CYP21A2 and its nearby pseudogene CYP21A1P. The current gold standard, PCR-based Sanger sequencing combined with multiplex ligation-dependent probe amplification (MLPA), is labor-intensive, costly, and amenable to PCR bias. Furthermore, it is not reliable in detecting complex structural variants, and it provides no information on whether variants are located on the same allele or not. The purpose of this study was to develop a method based on long-read sequencing (LRS) for accurate diagnostics of CYP21A2 variants and their phasing. Adaptive sampling (AS-)-LRS with chromosome 6 as region-of-interest was applied to DNA from 34 patients clinically diagnosed with CAH. To overcome mapping challenges in the highly homologous regions, we developed NanoCAH, a custom bioinformatic tool that accurately distinguishes between CYP21A2 and CYP21A1P reads. Using AS-LRS and NanoCAH, we genetically confirmed CYP21A2-associated CAH in 32 (94%) of the patients, including reliable phasing of the variants without the need for parental testing. AS-LRS clarified previously ambiguous findings, including the detection of chimeric genes, deletions, and missed variants. Compared to current gold standard methods, AS-LRS proved to be faster and more scalable, while providing greater accuracy in detecting variants within the CYP21A
2. SGLT2 inhibitors and mortality in older adults with diabetic kidney disease: A target trial emulation study.
In a nationwide Japanese target trial emulation of 5,371 adults ≥65 years with DKD, initiating SGLT2 inhibitors was associated with roughly 50% lower all-cause mortality compared with DPP-4 inhibitors over a median 2.23 years, with consistent per-protocol results. Benefits were most evident below age ~80 and at BMI ≥22 kg/m².
Impact: Provides robust real-world evidence suggesting a substantial survival benefit of SGLT2 inhibitors in a high-risk older DKD population, informing treatment selection where RCT data are limited.
Clinical Implications: For older adults with DKD—especially under 80 years and BMI ≥22 kg/m²—SGLT2 inhibitors should be prioritized over DPP-4 inhibitors when feasible, while acknowledging observational design and potential confounding.
Key Findings
- SGLT2 inhibitor initiation was associated with lower all-cause mortality vs DPP-4 inhibitors (HR 0.51; 95% CI 0.38–0.70).
- Results were consistent in per-protocol sensitivity analysis (HR 0.50; 95% CI 0.35–0.73).
- Effect modification suggested stronger benefit up to ~80 years of age and at BMI ≥22 kg/m².
Methodological Strengths
- Target trial emulation with propensity score overlap weighting and ITT plus per-protocol analyses.
- Nationwide claims and health checkup database with a sizable older DKD cohort and spline-based effect modification assessment.
Limitations
- Observational design with potential residual confounding and channeling bias.
- Medication exposure and comorbidities derived from claims may introduce misclassification; generalizability outside Japan uncertain.
Future Directions: Pragmatic randomized trials in very old and frail DKD patients, mechanistic studies on survival pathways, and comparative effectiveness across broader cardiometabolic profiles.
AIMS: Randomized controlled trials on sodium-glucose cotransporter 2 (SGLT2) inhibitors have yielded inconsistent findings regarding mortality benefits. It remains unclear whether, and in which subgroups, SGLT2 inhibitors confer survival benefits in older adults with diabetic kidney disease (DKD). MATERIALS AND METHODS: We emulated a target trial using a nationwide claims and health checkup database in Japan to compare all-cause mortality between SGLT2 and dipeptidyl peptidase-4 (DPP4) inhibitor initiators among 5371 adults aged ≥65 years with DKD. The primary outcome was all-cause mortality. Hazard ratios (HRs) were estimated using propensity score overlap weighting and Cox proportional hazards models in an intention-to-treat analysis. A per-protocol analysis with inverse probability of censoring weighting was conducted as sensitivity analysis. Effect modification by age, body mass index (BMI) and Charlson comorbidity index (CCI) was assessed using restricted cubic spline models. RESULTS: During a median follow-up of 2.23 (IQR, 1.07-3.49) years, 437 deaths occurred. SGLT2 inhibitor use was associated with significantly lower all-cause mortality than DPP4 inhibitors (HR, 0.51; 95% confidence interval, 0.38-0.70), with consistent results in the per-protocol analysis (HR, 0.50; 95% confidence interval, 0.35-0.73). Survival benefit was evident up to about 80 years of age and among individuals with BMI ≥22 kg/m CONCLUSIONS: In this target trial emulation study, SGLT2 inhibitors were associated with lower mortality in older adults with DKD, particularly those under 80 years and with BMI ≥22 kg/m
3. HbA1c underperforms in identifying abnormal glucose tolerance in the presence of G6PD deficiency: Insight from the Africans in America study.
Among 534 sub-Saharan African participants, G6PD deficiency lowered HbA1c by ~0.9% without differences in glucose, resulting in 0% sensitivity (and 100% specificity) of HbA1c for detecting abnormal glucose tolerance in G6PD-D individuals. Enzymatic assays aligned perfectly with genotyping (after excluding female heterozygotes), highlighting the need for enzyme-based status determination in women.
Impact: This study quantifies a clinically critical failure mode of HbA1c in a high-prevalence population for G6PD deficiency, underscoring the need to reconsider diabetes screening strategies to avoid missed diagnoses and inequities.
Clinical Implications: In individuals at risk for G6PD deficiency—particularly of African ancestry—diagnosing abnormal glucose tolerance should rely on glucose-based tests (e.g., OGTT, fasting/2-hour glucose) rather than HbA1c; enzymatic assays are necessary for status determination in heterozygous women.
Key Findings
- HbA1c was ~0.9% lower in G6PD-D vs normal G6PD activity with no glucose differences.
- HbA1c sensitivity for abnormal glucose tolerance was 0% in G6PD-D (specificity 100%).
- Genotype and enzymatic assays were 100% concordant after excluding heterozygous women, emphasizing the need for enzyme testing in heterozygotes.
Methodological Strengths
- Use of OGTT as the diagnostic gold standard for abnormal glucose tolerance.
- Parallel assessment of G6PD status by genotyping and enzymatic assay, clarifying heterozygote limitations.
Limitations
- Cross-sectional design limits causal inference; subgroup sample sizes (e.g., G6PD-D with Abnl-GT) are modest.
- Generalizability may be limited beyond sub-Saharan Africans living in the US; some heterozygous women lacked enzyme testing.
Future Directions: Prospective diagnostic accuracy studies across diverse ancestries, policy evaluations of alternative screening algorithms, and integration of point-of-care G6PD enzyme testing in diabetes screening workflows.
G6PD deficiency (G6PD-D) variants are associated with lower hemoglobin A1c (HbA1c) concentrations, raising concerns about the diagnostic efficacy of HbA1c for abnormal glucose tolerance (Abnl-GT) in Africans, in whom risk of G6PD-D and Abnl-GT is high. G6PD-D is assessed using genotyping or an enzymatic assay, but because G6PD-D is X-linked, the enzymatic assay is necessary for determining status for women heterozygous for deficiency variants. We assessed: 1) ability of HbA1c to detect Abnl-GT by G6PD-D; 2) concordance of genotyping and enzymatic assay for G6PD-D in sub-Saharan Africans living in the US. 534 participants of the Africans in America study were included, with HbA1c ranging from 3.1-11.3%. Abnl-GT determined by HbA1c (≥5.7%) was compared to the diagnostic standard, the oral glucose tolerance test (fasting glucose≥100 mg/dL and/or 2h glucose≥140 mg/dL). G6PD-D status was determined by genotype (n = 263), enzymatic assay (n = 83), or both (n = 188). G6PD-D could not be determined for 13 women heterozygotes with only genotype data. In the remaining participants, HbA1c was 0.9% lower among those with G6PD-D (4.6 ± 0.5; range 3.1-5.6) compared to those with normal G6PD activity (5.5 ± 0.6; range 4.2-11.3; P < 0.001). Glucose concentrations did not differ between groups. HbA1c sensitivity and specificity for Abnl-GT were 0% (0/17) and 100% (37/37) among those with G6PD-D, and 50% (98/195) and 80% (217/272) among those with normal activity. After excluding women heterozygotes, concordance for G6PD-D detection by genotype and the enzymatic assay was 100%. G6PD-D was associated with ~0.9% lower HbA1c in this study, leading to a failure of HbA1c to identify Abnl-GT in these participants. Such a dramatic difference in a screening tool could have consequences in practice, including late diagnosis, undertreatment, and increased complications among those with G6PD-D. Additionally, the results for the enzymatic assay were perfectly concordant with the genotype results for G6PD-D. However, as genotype alone cannot predict G6PD-D in heterozygous women, the enzymatic assay was more informative.