Reading disabilities (RDs) are a particular neurodevelopmental learning disorder, defined as a specific and significant impairment in reading ability that cannot be explained by deficits in intelligence, learning opportunities, motivation, or sensory acuity, also known as dyslexia. It can occur in areas of basic reading skills, written expression, listening, and speaking (1, 2). Children or adolescents with RDs may experience psychosocial consequences such as anxiety, depression, and low self-esteem (3–5), and they may have difficulties attaining educational degrees or high-income levels in their future life (6, 7).

Approximately 3–12% of individuals around the world have RDs (8). Studies conducted in English-speaking countries show a wide prevalence range of dyslexia (from 5 to 17.5%) (9–13). In China, the prevalence of dyslexia in school-aged children ranges from 3.0 to 12.6% (14). Epidemiological surveys have reported that the prevalence rates of dyslexia in Guangzhou, Xinjiang, Qianjiang, and Shantou are 5.4, 7.0, 3.9, and 5.4% (15–18), respectively.

Previous cross-sectional studies have revealed some of the risk factors associated with RDs, such as gender (19), socioeconomic status, parental educational levels, the home literacy environment (15), a difficult vaginal delivery, and preterm birth (9). Nevertheless, the risk factors associated with RDs could vary across different languages, races, and cultures. Identification of the risk factors for RDs may be helpful to increase understanding of the pathogenic mechanism.

Xinjiang is located in northwestern China and is a multiethnic settlement, where Central and Western Asian cultures converge. The region is populated by various ethnic groups, of which Uyghur and Han are the major ones. Shihezi City is located in the northern part of the Xinjiang Uygur Autonomous Region, China, which has a population of 624,400 and an area of 456.84 km². In this city, there are 36,000 ethnic minorities, accounting for 5.4% of the population, and it is home to 27 ethnic groups, including the Han, Hui, Uighur, and Kazakh. Most ethnic minorities have their own unique genetic and cultural backgrounds, and they differ widely from European and Han people in terms of their beliefs, lifestyles, and languages. In contrast to that of Han children, the national languages of minority children, such as Uighur and Kazakh children, belong to the Altaic-Turkic language family, which is different from the Chinese language (belonging to the Sino-Tibetan language family). Children of ethnic minorities, on the one hand, have lived in a Chinese environment from birth and have learned unified Mandarin Chinese and standardized Chinese characters since kindergarten (approximately 3 years old). Chinese is widely used in their daily lives. On the other hand, ethnic minority parents often communicate with their children in their own language at home and teach their children to read and write their own traditional ethnic characters. Learning Chinese remains a particularly challenging task for children from ethnic minority groups, whose first language is not Chinese (20). Zhao et al. found that in Kashgar and Aksu, cities of Xinjiang Province, the rate of RDs in Uighur children is 7.93%, which is higher than the positive screening rate for Han children in the same region (3.89%) (16). Children from minority groups receive education in both their own language and Chinese from childhood, and the mechanism of RDs may be different from that in Han children (21).

This study aimed to investigate the prevalence of RDs in the multiethnic city and to explore if there exist differences in the prevalence of the RDs and potential risk factors between Han and ethnic minority children.

This study focused on the prevalence and risk factors for children with RDs in a multiethnic city. From this study, the main findings were as follows. The prevalence of RDs was 3.4% in Shihezi City, 3.28% in Han children, 7.42% in Uighur children, and 2.82% in Hui children. The prevalence of RDs differed between Han and ethnic minority children. Factors including learning habits and the home literacy environment were significantly associated with RDs.

Due to differences in the methods used to diagnose RDs and cultural differences, the prevalence of RDs was not consistent between studies. The prevalence of dyslexia in China was reported to range from 3.0 to 12.6% (14). In our study, the prevalence of RDs was 3.4%. According to the International Classification of Diseases (ICD-10), RDs are a specific and significant impairment in the development of reading skills that is not solely accounted for by mental age, visual acuity problems, or inadequate schooling (24). RDs are specific cognitive disorders, which cannot be explained by more general factors. It is the general consensus that the core problem in RDs is difficulty decoding text, and those who experience severe difficulties with decoding will usually experience associated problems of reading comprehension (25), which requires a written language assessment with a standardized test. We believe that standardized tests can be used to diagnose dyslexia with greater sensitivity and specificity. However, in China, due to the large population, the DCCC scale is more suitable for screening a large sample population and facilitates early detection. This scale includes assessments of decoding, word spelling, and writing. To accurately screen out children with RDs, we excluded children with intellectual disabilities, brain injuries, visual, and auditory disorders, epilepsy, and other psychiatric diseases that may cause difficulties in learning to read. We then used the DCCC scale to screen children with RDs in a multiethnic city and obtained similar conclusions to those in other regions.

Due to the differences in linguistic and genetic backgrounds between Han and ethnic minority children, the rate of RDs varies between studies. Zhao et al. (16) found that the dyslexia prevalence in the Han group (3.9%) was significantly lower than that of the Uighur group (7.0%), which was in close agreement with our study. In our study, the prevalence of RDs among Uighur children was 7.42%, which was significantly higher than that of Han children. However, there was no significant difference in the prevalence of RDs between Han and Hui children. There were several possible reasons for this result. The customs of the Hui nationalities are similar to those of the Han, Mongolian, and Uighur nationalities. Chinese is the general language of Hui nationalities, while the Uighurs have their own unique living habits and customs. Uighur is widely spoken in their family life. Uighur, an alphabetical language with a linear, one-dimensional alphabet (26), differs from Chinese (ideograph language) in linguistic characteristics (27). Most school-age Han and Hui children are Chinese monolinguals, whereas almost all school-age Uighur children are Uighur-Chinese bilinguals. They usually use their own language in communication with their families at home and use Mandarin Chinese at school and in social activities. Given these circumstances, children’s Chinese learning may be affected by Uighur learning habits (such as reading direction), and they easily get confused with the initials and rhymes. Previous studies have shown that when children are educated in two languages, their learning of the second language may be affected by the first language (28–30). Due to the differing characteristics of Uighur and Chinese, a bilingual imbalance has occurred in Uighur children. The reading direction of Uighur is from right to left, while that of Chinese is from left to right. Although Chinese is not considered a full second language for ethnic minority children, there are still some differences compared with Han children who were exposed to Chinese at birth. This makes it more difficult for them to learn Chinese. This shows that the bilingual environment may be one of the reasons why the prevalence of RDs among Uighur children is higher than that in other ethnic children. Further research in this area is warranted in the future. In addition to language differences, Uighurs rarely intermarry with other nationalities due to their cultural customs, so their population mobility, and genetic drift are low (31). The Uighur population has mixed ancestry and has been deemed to be genetically related to European and East Asian populations, so they may carry some genetic information, especially in terms of the molecular genetics of various diseases (32). Cultural, linguistic, and genetic differences may be responsible for the higher prevalence of RDs in Uighurs.

A large quantity of research also reported that more boys than girls suffer from dyslexia (12, 33). In this study, the gender ratio was nearly 2:1 in favor of boys among children with RDs. Logistic regression revealed that the risk for boys was 1.9 times as high as that in girls. Interestingly, we also found that the risk to boys was 1.5 times as high as that in girls among Han children, while there were no obvious gender differences among ethnic minorities. Previous studies found that the gender imbalance may be related to genetic differences, inherited features, and the development of cognition. One recent genetic study found that the CNTNAP2 gene variant was associated with gender differences among dyslexic children (34). Functional brain imaging studies have shown that men and women exhibit different brain activation patterns during speech processing (35). Neuroimaging and genetic studies have attributed this difference to the presence of hormone-related protective factors in women (36). Whether there are gender-based differences in the risk of RDs in ethnic minority children needs further research.

According to the results of logistic regression, we found that learning habits had a significant impact on the occurrence of dyslexia. Freeman et al. (37) found that active learning could improve students’ test scores. Gori et al. (38) observed that poorer temporal skills were correlated with lower reading skills in dyslexic children, suggesting that this temporal capability could be linked to reading abilities. Children with RDs usually have difficulty in reading, and failure to read reduces their motivation to learn, so children in this group have greater difficulty completing homework than those in the control group.

The home literacy environment was found to have an association with RDs in our study. The family literacy environment is an important predictor of children’s language and literacy development (39). Having an early learning environment in terms of vocabulary may lead to better literacy skills (40, 41). Early word-level literacy around 5.5 years had an effect on reading comprehension (42). Compared with dyslexic children, families of non-dyslexic children may provide a richer literacy environment (43). Learning to read in the early stages of education can lay the foundation for future literacy development and academic success (44–46). Starting to read Chinese books during kindergarten (3–5 years old) can reduce the risk of RDs in children of ethnic minorities. To make minority children more adaptable to the comprehensive Chinese teaching model, Xinjiang began to implement preschool bilingual education in 2005 to help minority children integrate into the Chinese language environment as early as possible. Our results proved it. It is recommended that parents of ethnic minorities should help their children be exposed to Chinese and overcome language barriers as early as possible. A good home literacy environment can increase children’ interest in reading and improve children’ reading skills (47). Based on our results, early literacy and reading more books can help to reduce the risk of RDs for both Han children and minority children.

This study showed that the learning habits and home literacy environment may be associated with RDs. The results of our study identified the risk factors that were associated with differences in the prevalence of RDs between Han and ethnic minority children. However, this study still has several limitations. This study was carried out in one city in China, and we could only generalize the prevalence to other cities that are similar to Shihezi City. Considering the large population in China, it is hard to screen the child with RD-based schools using the standardized tests that are conducted individually. The standardized tests may be considered to use for further research in the future.

Nevertheless, more studies involving a greater diversity of areas and races are urgently needed to prove the reliability and validity of DCCC in the future. There were many risk factors associated with RDs, and only some of these were analyzed in our study. In addition to the environmental factors, the etiology of RDs also involves neurology, genetics, and psychology. Further research is required to understand the genetic mechanisms underlying RDs in ethnic minority children and whether they differ from those in Han children.

The original contributions presented in this study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author/s.

The studies involving human participants were reviewed and approved by written informed consents were obtained from all participants and the next of kin, caretakers, or guardians on the behalf of the participants involved in the study. Besides, the study was approved by the Ethical Committee of Medical Association of Tongji Medical College, Huazhong University of Science and Technology. Written informed consent to participate in this study was provided by the participants’ legal guardian/next of kin.

YF contributed to the conceptualization, methodology, formal analysis, investigation, and writing—original draft. QL, XX, QJ, KZ, PX, and XW collected the data and carried out the initial analysis. PZ and RS conceptualized and designed the study, collected the data, drafted the initial manuscript, reviewed, and revised the manuscript. All authors contributed to the article and approved the submitted version.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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