Incidence of inborn errors of metabolism detected by tandem mass spectrometry in China: A census of over seven million newborns between 2016 and 2017.

BACKGROUND: The incidence of inborn errors of metabolism varies widely across countries. Very few studies have analyzed the incidence of these disorders in Mainland China. We aimed to estimate the overall and disease-specific incidences of inborn errors of metabolism in Chinese newborns and investigate the geographical distribution of these disorders. METHODS: A national cross-sectional survey was conducted to investigate newborn inborn errors of metabolism screening by tandem mass spectroscopy in Mainland China between 2016 and 2017. A total of 246 newborn screening centers were surveyed using a standardized questionnaire. We examined the cumulative and disease-specific incidences of inborn errors of metabolism in Mainland China as a whole and in different geographical locations. RESULTS: Over 7 million newborns were screened and 2747 were diagnosed with inborn errors of metabolism, yielding an overall incidence of 38.69 per 100,000 births (95% confidence interval: 37.27-40.17). The most common disorders were amino acid disorders (17.14 per 100,000 births, 95% confidence interval: 16.21-18.13), followed by organic acid disorders (12.39 per 100,000 births, 95% confidence interval: 11.60-13.24) and fatty acid oxidation disorders (9.16 per 100,000 births, 95% confidence interval: 8.48-9.89). The overall and disease-specific incidence rates differed significantly across geographical locations (P < 0.001). CONCLUSIONS: The overall incidence of inborn errors of metabolism in Chinese newborns is relatively high. It is urgent to establish the recommended uniform screening panel for inborn errors of metabolism to guide the national and regional tandem mass spectroscopy newborn screening programs.

Phenylketonuria incidence in China between 2013 and 2017 based on data from the Chinese newborn screening information system: a descriptive study.

OBJECTIVE: This study examines the incidence and spatial clustering of phenylketonuria (PKU) in China between 2013 and 2017. METHODS: Data from the Chinese Newborn Screening Information System were analysed to assess PKU incidence with 95% CIs by province, region and disease severity. Spatial clustering of PKU cases was analysed using global and local spatial autocorrelation analysis in the geographic information system. RESULTS: The database contained 4925 neonates with confirmed PKU during the study period, corresponding to an incidence of 6.28 (95% CI: 6.11 to 6.46) per 100 000 neonates screened. Incidence was highest in the provinces of Gansu, Ningxia and Qinghai, where it ranged from 19.00 to 28.63 per 100 000 neonates screened. Overall incidence was higher in the northern part of the country, where classical disease predominated, than in the southern part, where mild disease predominated. PKU cases clustered spatially (global Moran's I=0.3603, Z=5.3097, p<0.001), and local spatial autocorrelation identified four northern provinces as high-high clusters (Gansu, Qinghai, Ningxia and Shanxi). CONCLUSIONS: China shows an intermediate PKU incidence among countries, and incidence differs substantially among Chinese provinces and between northern and southern regions. Our results suggest the need to focus efforts on screening, diagnosing and treating PKU in high-incidence provinces.