Biomedical subjects

Joohon Sung

Publications and source records attributed to Joohon Sung.

3 recordsLinked to original sources

PubMed2026

Genetic and Environmental Influences on Caffeine Intake in Korean Twins.

Caffeine intake may be influenced by both genetic and environmental factors. This study aimed to examine the genetic contribution to variation in coffee and tea drinking, as well as total caffeine intake. A total of 1,106 Korean twins, comprising 456 monozygotic and 97 dizygotic twin pairs aged 30 years or older, from the Healthy Twin Study were included. Structural equation models were used to assess heritability estimates and their 95% confidence intervals (CIs). Heritability (95% CI) was estimated at 0.29 (0.21, 0.37) for coffee drinking, 0.11 (0.02, 0.20) for tea drinking, and 0.27 (0.16, 0.38) for total caffeine intake, with the remaining variance in each trait attributed to unique environmental factors. The unique environmental factors contributed more substantially to coffee drinking than genetic factors during early adulthood, while the genetic contribution to tea drinking remained consistently low across all ages. In conclusion, coffee drinking, tea drinking, and total caffeine intake were partly heritable, with unique environmental factors playing a predominant role.

Humans↗

PubMed2025

Genetic influence on choroidal vascularity index.

PURPOSE: To investigate the heritability of genetic influence on macular choroidal vascularity index (CVI). METHODS: Total choroidal area (TCA), luminal area (LA), and CVI was measured using horizontal scan of spectral-domain optical coherence tomography with enhanced depth imaging in the 373 healthy twin participants. Characteristics of the participants were investigated, including age, sex, axial length, hypertension, diabetes, drinking habits, and smoking status. Univariate and subsequent multivariate regression analyses were performed to evaluate the associations of these factors with TCA, LA, and CVI. RESULTS: Patients who were older and had a higher intraocular pressure, higher diastolic blood pressure, and lower pulse pressure showed associations with lower CVI (p<0.001, p = 0.014, p = 0.005, and p = 0.015, respectively). The covariate-adjusted heritability (±standard error) of the CVI was 0.716 ± 0.091, and the heritabilities of the TCA and LA were 0.691 ± 0.089 and 0.634 ± 0.100, respectively. CONCLUSION: The TCA, LA, and CVI are highly heritable.

Humans↗

PubMed2024

Whole-genome sequences reveal zygotic composition in chimeric twins.

While most dizygotic twins have a dichorionic placenta, rare cases of dizygotic twins with a monochorionic placenta have been reported. The monochorionic placenta in dizygotic twins allows in utero exchange of embryonic cells, resulting in chimerism in the twins. In practice, this chimerism is incidentally identified in mixed ABO blood types or in the presence of cells with a discordant sex chromosome. Here, we applied whole-genome sequencing to one triplet and one twin family to precisely understand their zygotic compositions, using millions of genomic variants as barcodes of zygotic origins. Peripheral blood showed asymmetrical contributions from two sister zygotes, where one of the zygotes was the major clone in both twins. Single-cell RNA sequencing of peripheral blood tissues further showed differential contributions from the two sister zygotes across blood cell types. In contrast, buccal tissues were pure in genetic composition, suggesting that in utero cellular exchanges were confined to the blood tissues. Our study illustrates the cellular history of twinning during human development, which is critical for managing the health of chimeric individuals in the era of genomic medicine.

Humans↗