Genotypic spectrum and genotype-phenotype correlation in multi-ethnic neonates with hyperphenylalaninemia from Xinjiang, China

Abstract Background Hyperphenylalaninemia (HPA) exhibits distinct regional and ethnic heterogeneity in both genotypic profiles and phenotypic manifestations. However, as a region characterized by multi-ethnic habitation and profound cultural exchange, there remains a paucity of data regarding the genotype-phenotype correlation in patients from Xinjiang. This study aims to characterize the HPA-related gene mutation spectrum and phenotypic landscape in neonates with HPA from Xinjiang, evaluate genotype-phenotype correlation, and establish an evidence base for precise diagnosis and individualized clinical intervention. Results A total of 273 patients with HPA were enrolled in this study, comprising 150 Han, 42 Hui, 36 Uyghur, 15 Kazakh, 4 Mongolian, 3 Dongxiang, and 23 individuals of unavailable ethnic origin. Next-generation sequencing was employed to identify variants in the phenylalanine hydroxylase ( PAH ) gene and Tetrahydrobiopterin (BH 4 ) metabolic pathway genes [6-pyruvoyltetrahydropterin synthase ( PTS ), GTP cyclohydrolase 1 ( GCH1 ), quinoid dihydropteridine reductase ( QDPR )]. Putative pathogenic variants were validated via Sanger sequencing in trios. These genetic data were integrated with clinical phenotypes to perform association analysis using Genotype-Phenotype Value ( GPV ). A total of 101 distinct variants were identified in 273 patients, with missense mutations being predominant (71.29%, 72/101). The most frequent PAH mutations were c.158G>A (p.Arg53His) (15.38%, 84/546) and c.728G>A (p.Arg243Gln) (10.07%, 55/546). Notably, c.158G>A was highly enriched in Hui, Uyghur, and Kazakh populations, while ethnic-specific variants such as c.688G>A in the Uyghur population were also observed. Compound heterozygosity was the primary genotypic pattern (63.98%), and mild HPA was the most common phenotype (64.10%). Genotype-based phenotype prediction achieved accuracies of 98.78% for mild hyperphenylalaninemia, 46.15% for mild PKU and 81.48% for classical PKU. Prediction accuracy reached 100% for homozygous mutations and 88.29% for heterozygous mutations. Furthermore, GPV was significantly negatively correlated with blood phenylalanine levels ( r =-0.905, R 2 =0.819, p =0.001). Conclusions The genetic landscape of HPA in Xinjiang exhibits distinct regional features driven by unique ethnic genetic backgrounds. The high-frequency mild mutation c.158G>A in the PAH gene, distributed across multiple ethnicities, along with other ethnic-specific variants constitutes a region-specific mutation spectrum. This profile dictates clinical severity through the interplay of variant type and compound heterozygosity. Our findings confirm the clinical utility of the GPV in these multi-ethnic cohorts, and expand the global PAH mutation database.