Our results support that iNOS polymorphisms are associated with the risk of HSP and may strongly contribute to the genetic basis of individual differences in the progression to nephritis among children with HSP in the Chinese Han population. What is Known: • The etiology of HSP is unknown, but the genetic factors may play an important role in the pathogenesis of HSP. • iNOS could contribute to the development and clinical manifestations of HSP, and this has not been studied extensively so far. What is New: • Our results support that iNOS polymorphisms not only are associated with HSP risk but also strongly contribute to the genetic basis of individual differences in the progression of HSP to nephritis among Chinese Han children.

Background: Citrin deficiency (CD) is an autosomal recessive disease resulting from biallelic mutations of the SLC25A13 gene. This study aimed to investigate the molecular epidemiological features of CD in the Guangdong and Shaanxi provinces of China.Methods: A total of 3,409 peripheral blood samples from Guangdong and 2,746 such samples from Shaanxi province were collected. Four prevalent SLC25A13 mutations NG_012247.2 (NM_014251.3): c.852_855del, c.1638_1660dup, c.615+5G>A, and c.1751-5_1751-4ins(2684) were screened by using the conventional polymerase chain reaction (PCR)/PCR-restriction fragment length polymorphism and newly-developed multiplex PCR methods, respectively. The mutated SLC25A13 allele frequencies, carrier frequencies, and CD morbidity rates were calculated and then compared with the Chi-square and Fisher's exact tests. Results:The mutations were detected in 68 out of 6,818 SLC25A13 alleles in Guangdong and 29 out of 5,492 alleles in the Shaanxi population. The carrier frequencies were subsequently calculated to be 1/51 and 1/95, while the CD morbidity rates were 1/10,053 and 1/35,865, in the 2 populations, respectively. When compared with the Shaanxi population, Guangdong exhibited a higher frequency of mutated SLC25A13