MUTATION IN BRIEF HUMAN MUTATION Mutation in Brief #737 (2004) Online Carbonic Anhydrase II Deficiency Syndrome (Osteopetrosis with Renal Tubular Acidosis and Brain Calcification): Novel Mutations in CA2 Identified by Direct Sequencing Expand the Opportunity for Genotype-Phenotype Correlation Gul N. Shah 1 , Giuseppe Bonapace 1 , Peiyi Y. Hu 1 , Pietro Strisciuglio 2 , and William S. Sly 1 * 1 Department of Biochemistry, Saint Louis University School of Medicine, St. Louis, MO 63104; 2 Department of Pediatrics, University of Catanzaro, 88100 Catanzaro, Italy *Correspondence to: William S. Sly, M.D., Department of Biochemistry, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104; Tel.: 314-977-9201; Fax: 314-977-1183; E-mail: slyws@slu.edu Grant sponsor: National Institutes of Health (W.S.S.); Grant numbers: GM34182, DK40163, GM53405; Grant sponsors: M.U.R. and C.O.F.I.N. (P.S.); Grant numbers: 980618306-006; MM06182533-006 Communicated by Elizabeth Neufeld The carbonic anhydrase II (CA II) deficiency syndrome is an autosomal recessive disorder that produces osteopetrosis, renal tubular acidosis, and cerebral calcification. Other features include developmental delay, short stature, cognitive defects, and a history of multiple fractures by adolescence. With one exception, all patients with osteopetrosis and renal tubular acidosis examined have proven to have CA II deficiency. All CA II-deficient patients analyzed have been found to have mutations in the CA2 gene. Previously, we used single strand conformational (SSCP) analysis to identify exons to be sequenced from CA II- deficient patients. In this report, we amplified all seven exons by PCR from genomic DNA and directly sequenced the amplified products. Application of this method allowed identification of eleven new mutations in 21 patients referred for confirmation of the diagnosis of CA II deficiency. These mutations were scattered over the genome from exon 2 to 7. In two opportunities for prenatal diagnosis, one from cultured amniocytes and one from chorionic villus biopsy, we demonstrated the general utility of the direct sequencing method for prenatal DNA diagnosis. These studies expand our knowledge of the heterogeneity in mutations underlying the CA II deficiency syndrome. © 2004 Wiley-Liss, Inc. KEY WORDS: osteopetrosis; renal tubular acidosis; carbonic anhydrase II; CA2; prenatal diagnosis; cerebral calcification INTRODUCTION There are 13 known, active carbonic anhydrases (CAs), which differ in tissue distribution, subcellular localization, kinetics, and sensitivity to various carbonic anhydrase inhibitors (Kaunisto et al., 2002; Leppilampi et al., 2002; Parkkila et al., 2002; Sly and Shah, 2001; Winum et al., 2003). CA II is one of the most widespread of Received 15 December 2003; accepted revised manuscript 26 May 2004. © 2004 WILEY-LISS, INC. DOI: 10.1002/humu.9266