The CBI has filed a case and started investigation into alleged irregularities in the NEET-UG. The retest for students whose grace marks were withdrawn was held today. Only 52 per cent students of the over 1,500 who were eligible turned up to take the retest. The central government has assured it will carry out reforms in the National Testing Agency (NTA) to plug the gaps. The NEET-PG exam's postponement also dealt a blow to students.