Uncovering the Prevalence of Cystinosis through Genetic Analysis

Background: Cystinosis is a metabolic disease characterized by the accumulation of cystine most often presenting in an infantile nephropathic form caused by pathogenic variants in the CTNS gene. It is characterized by progressive loss of glomerular function leading to renal failure by the first decade of life, making early diagnosis crucial to improving outcomes. This study seeks to estimate the prevalence of cystinosis using a population genetics approach. Methods: The Human Genome Mutation Database (HGMD) was used to identify known pathogenic variants in CTNS, and the 1000 Genomes (1KG) database was used to identify CTNS variants in a cohort representing a healthy population. These two databases were intersected to identify disease-causing variants and their carriers in the general population. The Hardy-Weinberg equilibrium was used to calculate expected carrier and affected rates for cystinosis. Results: The allele frequency for all disease-causing alleles was calculated to be 0.016. The predicted affected rate was calculated to be 0.00027 (approximately 1:3680), and the predicted carrier rate was 0.032 (approximately 1:30). Conclusion: Compared to the reported clinical prevalence of between 1 in 100,000 to 1 in 200,000, the prevalence of cystinosis in this study was calculated to be 1 in 3,680. This significantly higher result may be due to the underdiagnosis of cystinosis or variable expressivity of variants presenting with a broad range of disease severity. These results support the proposal of newborn screening for early diagnosis and improved outcomes in infantile nephropathic cystinosis. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: https://www.internationalgenome.org/ I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors