This study identified a total of 14 chimeric TNXA/TNXB, but the results of MLPA combined with Long-PCR detection were all lack of exon 1-10 of CYP21A2. This indicates that CAH-X-CH1, CAH-X-CH2 and CAH-X-CH3 cannot be distinguished from each other. This evidence concerns the gene CYP21A2 and congenital adrenal hyperplasia.