To explore the incidence of various inborn errors of metabolism (IEM) in newborns in Hainan Province.

A total of 86 543 newborns born in Hainan Province from January 1 to December 31, 2024, whose guardians agreed to undergo neonatal IEM screening, were selected as the study subjects. Using tandem mass spectrometry detection technology, initial and re-screening of various IEM were conducted on dried blood spot specimens collected from the heels of newborn infants. For some newborns who tested positive in the rescreening, peripheral blood was collected, and the type of IEM and gene mutations were confirmed by whole exome sequencing (WES) detection technology. The positive rates of initial IEM screening among newborns of different genders, gestational ages, birth weights, ethnicities, and registered residences were compared by chi-square test, and further pairwise comparisons were performed using the chi-square splitting method, and the Bonferroni method was used to adjust the significance level. This study was conducted in accordance with the ethical standards of Hainan Women and Children′s Medical Center, and was approved by its Ethics Committee (Approval No.HNWCMC-2026-151).

①In 2024, there were 92 170 live births in Hainan Province, and 86 543 of them underwent IEM screening, with an IEM screening rate of 93.89%. Among these 86 543 newborns, the positive rate of initial IEM screening was 3.58% (3 094/86 543). And 2 591 cases underwent IEM rescreening, with an IEM rescreening rate of 83.74% (2 591/3 094). Among them, 245 cases were positive for IEM rescreening, the positive rate of IEM rescreening was 9.46% (245/2 591), and 136 (55.51%, 136/245) newborns underwent genetic testing, and 38 were finally diagnosed with IEM. The incidence rate of IEM in newborns was about 4.39×10^-4 (38/86 543). ②The positive rate of initial IEM screening in newborns with gestational age <37 weeks was higher than that in newborns with gestational age ≥37 to 42 weeks, and the difference was statistically significant (χ²=361.64, P<0.001). The overall comparison of the positive rate of initial IEM screening among newborns with different birth weights also showed a statistically significant difference (χ²=291.65, P<0.001). Further pairwise comparisons revealed that the positive rate of initial IEM screening in newborns with birth weight <2 500 g, ≥2 500 to 4 000 g, and >4 000 g differed significantly in any pairwise comparison (P≤0.001). The overall comparison of the positive rate of initial IEM screening among newborns of different ethnic groups showed a statistically significant difference (χ²=36.12, P<0.001). Further pairwise comparisons revealed that the positive rate of initial IEM screening in Li ethnic group newborns was higher than that in Han and Miao ethnic group newborns, and both the differences were statistically significant (P<0.001, P=0.006). The comparison of the positive rate of initial IEM screening among newborns with different registered residence also showed a statistically significant difference (χ²=80.62, P<0.001). Further pairwise comparisons revealed that the positive rate of initial IEM screening in newborns from ethnic minority cities and counties in Hainan Province was higher than that in newborns from Han ethnic group cities and counties in Hainan Province, and the difference was statistically significant (P<0.001). ③Among the 86 543 newborns, the detection rate of IEM-related gene mutation was 7.16×10^-4 (62/86 543). The top four detected gene mutations were SLC22A5, SLC25A13, ACADS, and ASS1 gene mutations. The top three detected gene mutation sites were c. 51C>G, c. 852_855del, and c.322G>A, respectively. ④Among the 38 newborns with IEM confirmed by genetic testing, 4 cases were amino acid metabolism disorders, 7 cases were organic acidemia, 5 cases were urea cycle disorders, and 22 cases were fatty acid oxidation metabolism disorders. The top three IEM diseases in terms of confirmed cases were primary carnitine deficiency (13 cases), short-chain acyl-CoA dehydrogenase deficiency (6 cases), and citrullinemia type Ⅱ (5 cases).

The incidence of IEM among newborns in Hainan Province is relatively high, with a diverse range of types. It is recommended to initiate early screening for various IEM in newborns and to enhance the management of infants with positive IEM screening results in Hainan Province.