Roxana Marino1, Natalia Perez Garrido1, Pablo Ramirez1, Guillermo Notaristéfano1, Angélica Moresco2, Maria Sol Touzon1, Elisa Vaiani3, Gabriela Finkielstain4, María Gabriela Obregón2, Viviana Balbi5, Ianina Soria6, Alicia Belgorosky3,7. 1. Molecular Biology Laboratory, Endocrinology Service, Hospital de Pediatría Prof. Dr. Juan P. Garrahan, Buenos Aires, Argentina. 2. Genetic Service, Hospital de Pediatría Prof. Dr. Juan P. Garrahan, Buenos Aires, Argentina. 3. Endocrinology Service, Hospital de Pediatría Prof. Dr. Juan P. Garrahan, Buenos Aires, Argentina. 4. Centro de Investigaciones Endocrinológicas "Dr César Bergadá" (CEDIE), CONICET-FEI-División de Endocrinología, Hospital de Niños Ricardo Gutiérrez, Endocrinology Service, Buenos Aires. Currently: Takeda Pharma, Argentina. 5. Endocrinology Service, Hospital de Niños Sor Maria Ludovica, La Plata, Argentina. 6. Endocrinology Service, Hospital de la Madre y el Niño, La Rioja, Argentina. 7. CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas), Argentina.
Abstract
CONTEXT: The syndrome CAH-X is due to a contiguous gene deletion of CYP21A2 and TNXB resulting in TNXA/TNXB chimeras. OBJECTIVE: To analyze TNXB gene status and to clinically evaluate the Ehlers-Danlos syndrome phenotype in a large cohort of Argentine congenital adrenal hyperplasia (CAH) patients to assess the prevalence of this condition in our population. METHODS: TNXB gene analysis was performed in 66 nonrelated CAH patients that were carriers of the CYP21A2 gene deletion. A molecular strategy based on multiplex ligation-dependent probe amplification and Sanger sequencing analysis was developed allowing for the detection of different, previously described TNXA/TNXB chimeras, named CH1, CH2, and CH3. The main outcome measures were TNXB status of CAH patients that were carriers of the CYP21A2 deletion in the homozygous or heterozygous state. RESULTS: TNXA/TNXB CH1 was found in 41%, CH2 in 29%, and CH3 in 1% of nonrelated alleles carrying the CYP21A2 deletion. Thus, overall 71% of alleles were found to carry a contiguous gene deletion. Sixty-seven percent of patients analyzed had a monoallelic form and 6% a biallelic form. All patients with the biallelic form had severe skin hyperextensibility and generalized joint hypermobility. CONCLUSION: Based on the high frequency of TNXB alterations found in CYP21A2 deletion carrier alleles, we recommend evaluating TNXB status in these patients, and assessing connective tissue dysplasia, including cardiologic alterations in positive cases. The number of patients undergoing cardiological evaluation should be expanded to determine the incidence of structural and functional abnormalities in this cohort.
CONTEXT: The syndrome CAH-X is due to a contiguous gene deletion of CYP21A2 and TNXB resulting in TNXA/TNXB chimeras. OBJECTIVE: To analyze TNXB gene status and to clinically evaluate the Ehlers-Danlos syndrome phenotype in a large cohort of Argentinecongenital adrenal hyperplasia (CAH) patients to assess the prevalence of this condition in our population. METHODS:TNXB gene analysis was performed in 66 nonrelated CAH patients that were carriers of the CYP21A2 gene deletion. A molecular strategy based on multiplex ligation-dependent probe amplification and Sanger sequencing analysis was developed allowing for the detection of different, previously described TNXA/TNXB chimeras, named CH1, CH2, and CH3. The main outcome measures were TNXB status of CAH patients that were carriers of the CYP21A2 deletion in the homozygous or heterozygous state. RESULTS:TNXA/TNXBCH1 was found in 41%, CH2 in 29%, and CH3 in 1% of nonrelated alleles carrying the CYP21A2 deletion. Thus, overall 71% of alleles were found to carry a contiguous gene deletion. Sixty-seven percent of patients analyzed had a monoallelic form and 6% a biallelic form. All patients with the biallelic form had severe skin hyperextensibility and generalized joint hypermobility. CONCLUSION: Based on the high frequency of TNXB alterations found in CYP21A2 deletion carrier alleles, we recommend evaluating TNXB status in these patients, and assessing connective tissue dysplasia, including cardiologic alterations in positive cases. The number of patients undergoing cardiological evaluation should be expanded to determine the incidence of structural and functional abnormalities in this cohort.