Epidemiologic observational study. Study will include two phases:

1. Retrospective cross-sectional phase: At this stage of the study, retrospective screenings are carried out at study sites and all juvenile cataract cases are planned to be determined.
2. Prospective phase: At this stage of the study, identified juvenile cataract cases as a result of retrospective screenings will be called to be invited to the sites and blood samples will be obtained for the cholestanol tests for the cases that have given Informed Consent.

This observational study is designed in two phases; retrospective and prospective. Retrospective part includes screening the patient database and / or patient files at ophthalmology clinics participating in the study and identifying patients diagnosed with idiopathic juvenile cataracts. The data of patients with idiopathic juvenile cataracts will be reviewed and the data of the patients meeting the inclusion/exclusion criteria will be recorded. Once this phase is completed, the prospective phase of the study will start and the patients meeting the criteria will be invited to the site to participate in the study. Current data will be collected from the patients who agree to participate in the study and the clinical status of the patients will be evaluated according to the Mignarri index. In addition, blood will be obtained from all patients to diagnose CTX disease. Blood samples will be sent to Duzen Laboratories in Ankara and analyzed for cholestanol.

Inclusion Criteria:

• Providing the written informed consent form
• The patient should be diagnosed with idiopathic bilateral juvenile cataract
• Idiopathic bilateral juvenile cataract should be diagnosed while the patient must be take a day from one year (age)
• Syria ciziten who take their citizenship of Turkey could be enrolled to the study after signing of Informed Consent Form that translated to mother tongue by sworn translation office approved by ethic committee.

Exclusion Criteria:

• If the patient has been diagnosed with CTX before his/her enrollment in the study,
• If the patient has been diagnosed with cataract due to any known reasons other than CTX including cataracts related to trauma,
• If the patient has been diagnosed with cataract due to cataractogenic treatments,
• If the patient has participated in an interventional clinical study within the last 30 days,
• If the patient and/or his/her legal representative does not provide consent to participate in the study,
• If the patient will not be able to fulfill study requirements according to the investigator's opinion,
• If the patient had used cholic acid or chenodeoxycholic acid on or before the date of participation in the study
• Pregnancy and/or lactation
• Syria citizen that have not Turkey citizenship will not enroll to the study.

All patients over 1 year old diagnosed as idiopathic bilateral juvenile cataracts will be included in the study at the study sites.