Repeated measurements of facial skin characteristics using the Janus-Ⅲ measurement system

GWAS Identifies Multiple Genetic Loci for Skin Color in Korean Women

Human skin color is largely determined by genetic factors. Recent GWASs have reported several genetic variants associated with skin color, mostly in European and African populations. In this study, we performed GWAS in 17,019 Korean women to identify genetic variants associated with facial skin color, quantitatively measured as CIELAB color index. We identified variants in three, one, and six genomic loci associated with facial skin color index L∗, a∗, and b∗ values, respectively, and replicated the associations (combined analysis P-value < 5.0 × 10^-8). The significant loci included variants in known genes (OCA2 rs74653330, BNC2 rs16935073, rs72620727 near KITLG, and SLC6A17 rs6689641) and to our knowledge previously unreported genes (SCARB1 rs10846744, SYN2 rs12629034, and LINC00486 rs6543678). This is GWAS to elucidate genetic variants of facial skin color in a Korean female population. Further functional characterizations of the investigated genes are warranted to elucidate their contribution to skin pigmentation-related traits.

GWAS Analysis of 17,019 Korean Women Identifies the Variants Associated with Facial Pigmented Spots

Variation in skin pigmentation can be affected by both environmental factors and intrinsic factors such as age, gender, and genetic variation. Recent GWASs revealed that genetic variants of genes functionally related to a pigmentation pathway were associated with skin pigmentary traits. However, these GWASs focused on populations with European ancestry, and only a few studies have been performed on Asian populations, limiting our understanding of the genetic basis of skin pigmentary traits in Asians. To evaluate the genetic variants associated with facial pigmented spots, we conducted a GWAS analysis of objectively measured facial pigmented spots in 17,019 Korean women. This large-scale GWAS identified several genomic loci that were significantly associated with facial pigmented spots (five previously reported loci and two previously unreported loci, to our knowledge), which were detected by UV light: BNC2 at 9p22 (rs16935073; P-value = 2.11 × 10^-46), PPARGC1B at 5q32 (rs32579; P-value = 9.04 × 10^-42), 10q26 (rs11198112; P-value = 9.66 × 10^-38), MC1R at 16q24 (rs2228479; P-value = 6.62 × 10^-21), lnc01877 at 2q33 (rs12693889; P-value = 1.59 × 10^-11), CDKN2B-AS1 at 9p21 (rs643319; P-value = 7.76 × 10^-9), and MFSD12 at 19p13 (rs2240751; P-value = 9.70 × 10^-9). Further functional characterization of the candidate genes needs to be done to fully evaluate their contribution to facial pigmented spots.

Comparative analysis of skin characteristics evaluation by a dermatologist and the Janus-III measurement system

BACKGROUND

The Janus-III measurement system evaluates the overall skin characteristics such as skin pore, wrinkle, sebum, porphyrin, skin pigmentation, and skin color using high-resolution facial images. The values are measured from five different facial areas, namely, the forehead, nose, corner of/skin below the eyes, and cheeks. Owing to its convenience and diverse measuring characteristics, Janus-III has been widely used in skin research and the cosmetic industry in Korea. In our previous study, we revealed the consistency and reliability of the system with repeatedly measured values. Its measuring performance was investigated statistically, but to make it more reliable for academic skin research, additional verification by a professional dermatologist is needed.

MATERIALS AND METHODS

In this study, we conducted comparative analysis of three skin characteristics (pigmented spot, skin color, and eye wrinkle) by a dermatologist and the Janus-III measurement system. We utilized 330 image data that were cropped from the whole facial images of 330 different participants to avoid correlation among the three measuring items. Pearson's correlation coefficient exhibited similar patterns between the system and the dermatologist's findings.

RESULTS

The main finding of our study was that the measured value of skin characteristics by the Janus-III system showed clear correlation with the values evaluated by a dermatologist, especially in a pigmented spot.

CONCLUSION

Therefore, it would be a plausible idea to consider the Janus-III system for specialized research of skin characteristics even with a small sample size.