title: Comparing the Southern blot method and polymerase chain reaction product analysis for chimeric RCCX detection in CYP21A2 deficiency.
abstract: The 3.2-kb TaqI-produced fragment of the CYP21A1P pseudogene and the 3.7-kb TaqI-produced fragment of the functional CYP21A2 gene exist on chromosome 6p21.3. We used the polymerase chain reaction (PCR) product and Southern blot method with TaqI endonuclease digestion to identify a chimeric RCCX module in two unrelated patients with congenital adrenal hyperplasia (CAH). After TaqI cleavage, the PCR product analysis revealed that patient 1 with the chimeric CYP21A1P/CYP21A2 gene in one allele and IVS2-12A/C>G in combination with the 707-714del mutation in the other allele produced a configuration of 3.2- and 2.4-kb fragments. Patient 2, who carried IVS2-12A/C>G in combination with the 707-714del mutation in one allele and the chimeric TNXA/TNXB gene in the other allele, presented with 3.2- and 2.3-kb fragments. However, Southern blot analysis showed that patients 1 and 2 produced 3.2-, 2.4-, and 2.5-kb fragments. We conclude that the chimeric CYP21A1P/CYP21A2 gene, IVS2-12A/C>G in combination with the 707-714del mutation, and the chimeric TNXA/TNXB gene cannot be distinguished by the Southern blot method. Conversely, the chimeric TNXA/TNXB gene was identified in the PCR product analysis due to the appearance of the 2.37-kb fragment, which indicates the occurrence of the chimeric TNXA/TNXB formation extending to the boundary of TNXA in the RCCX region.
authors: School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung 404, Taiwan. hhlee@mail.cmu.edu.tw
authors: Hsien-Hsiung
authors: HH
authors: Lee
authors: Yann-Jinn
authors: YJ
authors: Lee
authors: Mei-Chyn
authors: MC
authors: Chao
mesh_terms: D000312:Adrenal Hyperplasia, Congenital / Q000235:genetics; D000483:Alleles; D015139:Blotting, Southern / Q000379:methods*; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D013255:Steroid 21-Hydroxylase / Q000235:genetics* / Q000378:metabolism; D019063:Tenascin / Q000235:genetics / Q000378:metabolism
chemical_list: C074149:TNXA protein, human; D019063:Tenascin; C081865:tenascin X; C531510:CYP21A2 protein, human; D013255:Steroid 21-Hydroxylase