Population-based carrier screening and prenatal diagnosis of fragile X syndrome in East Asian populations

Identification of carriers of fragile X syndrome(FXS) with the subsequent prenatal diagnosis and knowledge of FXS-associated genetic profiles are essential for intervention in specific populations. We report the results of carrier screening of 39,458 East Asian adult women and prenatal diagnosis from 87 FXS carriers.The prevalence of FXS carriers and full mutation fetuses was estimated to be 1/581 and 1/3124 in East Asian populations, respectively. We confirmed the validity of the current threshold of CGG trinucleotide repeats for FMR1 categorization;the integral risks of full mutation expansion were approximately 6.0%,43.8%, and 100% for premutation alleles with 55—74, 75—89, and ≥ 90 CGG repeats, respectively. The protective effect of AGG(adenine-guanine-guanine nucleotides) interruption in East Asian populations was validated, which is important in protecting premutation alleles with 75—89 CGG repeats from full mutation expansion. Finally, family history was shown not an effective indicator for FXS carrier screening in East Asian populations, and population-based screening was more cost-effective. This study provides an insight into the largest carrier screening and prenatal diagnosis for FXS in East Asian populations to date. The FXSassociated genetic profiles of East Asian populations are delineated, and population-based carrier screening is shown to be promising for FXS intervention.

Identification of novel loci influencing refractive error in East Asian populations using an extreme phenotype design

The global "myopia boom" has raised significant international concerns. Despite a higher myopia prevalence in Asia, previous large-scale genome-wide association studies(GWASs) were mostly based on European descendants. Here, we report a GWAS of spherical equivalent(SE) in 1852 Chinese Han individuals with extreme SE from Guangzhou(631 <-6.00 D and 574 > 0.00 D) and Wenzhou(593 <-6.00 D and54 >-1.75 D), followed by a replication study in two independent cohorts with totaling 3538 East Asian individuals. The discovery GWAS and meta-analysis identify three novel loci, which show genome-wide significant associations with SE, including 1 q25.2 FAM163 A, 10 p11.22 NRP1/PRAD3, and 10 p11.21 ANKRD30 A/MTRNR2 L7, together explaining 3.34% of SE variance. 10 p11.21 is successfully replicated.The allele frequencies of all three loci show significant differences between major continental groups(P < 0.001). The SE reducing(more myopic) allele of rs10913877(1 q25.2 FAM163 A) demonstrates the highest frequency in East Asians and much lower frequencies in Europeans and Africans(EAS = 0.60,EUR = 0.20, and AFR = 0.18). The gene-based analysis additionally identifies three novel genes associated with SE, including EI24, LHX5, and ARPP19. These results provide new insights into myopia pathogenesis and indicate the role of genetic heterogeneity in myopia epidemiology among different ethnicities.