steroid 21 hydroxylase


Summary: An adrenal microsomal cytochrome P450 enzyme that catalyzes the 21-hydroxylation of steroids in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP21 gene, converts progesterones to precursors of adrenal steroid hormones (CORTICOSTERONE; HYDROCORTISONE). Defects in CYP21 cause congenital adrenal hyperplasia (ADRENAL HYPERPLASIA, CONGENITAL).

Top Publications

  1. White P, Speiser P. Congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Endocr Rev. 2000;21:245-91 pubmed
    ..Glucocorticoid and mineralocorticoid replacement are the mainstays of treatment, but more rational dosing and additional therapies are being developed. ..
  2. Robins T, Bellanne Chantelot C, Barbaro M, Cabrol S, Wedell A, Lajic S. Characterization of novel missense mutations in CYP21 causing congenital adrenal hyperplasia. J Mol Med (Berl). 2007;85:247-55 pubmed
    ..This has relevance for diagnosis, prognosis, and genetic counseling for affected families. ..
  3. Kharrat M, Tardy V, M rad R, Maazoul F, Jemaa L, Refai M, et al. Molecular genetic analysis of Tunisian patients with a classic form of 21-hydroxylase deficiency: identification of four novel mutations and high prevalence of Q318X mutation. J Clin Endocrinol Metab. 2004;89:368-74 pubmed
    ..Our results have shown a good genotype/phenotype correlation in the case of most mutations. This is the first report of screening for mutations of 21-hydroxylase gene in the Tunisian population and even in the Arab population. ..
  4. Grischuk Y, Rubtsov P, Riepe F, Grötzinger J, Beljelarskaia S, Prassolov V, et al. Four novel missense mutations in the CYP21A2 gene detected in Russian patients suffering from the classical form of congenital adrenal hyperplasia: identification, functional characterization, and structural analysis. J Clin Endocrinol Metab. 2006;91:4976-80 pubmed
    ..Moreover, this report demonstrates that the combination of in vitro enzyme analysis and molecular modeling can yield novel insights into CYP450 structure-functional relationships. ..
  5. Krone N, Riepe F, Partsch C, Vorhoff W, Bramswig J, Sippell W. Three novel point mutations of the CYP21 gene detected in classical forms of congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Exp Clin Endocrinol Diabetes. 2006;114:111-7 pubmed
    ..Knowledge of the residual 21-hydroxylase function improves both genetic counselling and individual clinical management in CAH patients. ..
  6. Concolino P, Satta M, Santonocito C, Carrozza C, Rocchetti S, Ameglio F, et al. Linkage between I172N mutation, a marker of 21-hydroxylase deficiency, and a single nucleotide polymorphism in Int6 of CYP21B gene: a genetic study of Sardinian family. Clin Chim Acta. 2006;364:298-302 pubmed
    ..The analysis of linkage between specific mutations and this SNPs, especially if focused on genetic familial studies, may improve the quality of genetic analysis of 21-hydroxylase deficiency. ..
  7. Baumgartner Parzer S, Fischer G, Vierhapper H. Predisposition for de novo gene aberrations in the offspring of mothers with a duplicated CYP21A2 gene. J Clin Endocrinol Metab. 2007;92:1164-7 pubmed
  8. Robins T, Carlsson J, Sunnerhagen M, Wedell A, Persson B. Molecular model of human CYP21 based on mammalian CYP2C5: structural features correlate with clinical severity of mutations causing congenital adrenal hyperplasia. Mol Endocrinol. 2006;20:2946-64 pubmed
    ..Structural features deduced from the models are in good correlation with clinical severity of CYP21 mutants, which shows the applicability of a modeling approach in assessment of new CYP21 mutations. ..
  9. Friães A, Rêgo A, Aragüés J, Moura L, Mirante A, Mascarenhas M, et al. CYP21A2 mutations in Portuguese patients with congenital adrenal hyperplasia: identification of two novel mutations and characterization of four different partial gene conversions. Mol Genet Metab. 2006;88:58-65 pubmed
    ..9%. With this study the molecular basis of CAH was characterized, for the first time, in Portuguese patients, providing useful results for clinicians in terms of prediction of disease severity, genetic and prenatal counseling. ..

More Information


  1. Wester M, Johnson E, Marques Soares C, Dansette P, Mansuy D, Stout C. Structure of a substrate complex of mammalian cytochrome P450 2C5 at 2.3 A resolution: evidence for multiple substrate binding modes. Biochemistry. 2003;42:6370-9 pubmed publisher
  2. Stikkelbroeck N, Hoefsloot L, de Wijs I, Otten B, Hermus A, Sistermans E. CYP21 gene mutation analysis in 198 patients with 21-hydroxylase deficiency in The Netherlands: six novel mutations and a specific cluster of four mutations. J Clin Endocrinol Metab. 2003;88:3852-9 pubmed
  3. Kleinle S, Lang R, Fischer G, Vierhapper H, Waldhauser F, Fodinger M, et al. Duplications of the functional CYP21A2 gene are primarily restricted to Q318X alleles: evidence for a founder effect. J Clin Endocrinol Metab. 2009;94:3954-8 pubmed publisher
    ..None of these five patients had the above mentioned HLA haplotype. The majority of individuals in whom Q318X mutations are detected carry a duplicated functional CYP21A2 gene and the rare HLA-B*50-Cw*06 haplotype. ..
  4. Bachelot A, Chakthoura Z, Rouxel A, Dulon J, Touraine P. Classical forms of congenital adrenal hyperplasia due to 21-hydroxylase deficiency in adults. Horm Res. 2008;69:203-11 pubmed publisher
  5. Loidi L, Quinteiro C, Parajes S, Barreiro J, Lestón D, Cabezas Agricola J, et al. High variability in CYP21A2 mutated alleles in Spanish 21-hydroxylase deficiency patients, six novel mutations and a founder effect. Clin Endocrinol (Oxf). 2006;64:330-6 pubmed
    ..A great diversity of haplotypes with a large spectrum of mutated alleles was found. The frequency of the V281L mutation was the highest reported and the relatively high frequency of R444X was the result of a founder effect. ..
  6. Lee H, Chang S, Lo F, Chao H, Lin C. Duplication of 111 bases in exon 1 of the CYP21 gene is combined with deletion of CYP21P-C4B genes in steroid 21-hydroxylase deficiency. Mol Genet Metab. 2003;79:214-20 pubmed
    ..Possibly, the additional 111-base duplicated coding sequence may be generated by multiple intergenic recombinations, while there seems to be no relationship with deletion of the CYP21P-C4B regions. ..
  7. Lee H, Niu D, Lin R, Chan P, Lin C. Structural analysis of the chimeric CYP21P/CYP21 gene in steroid 21-hydroxylase deficiency. J Hum Genet. 2002;47:517-22 pubmed
    ..It is plausible that both consensus sequences are responsible for the gene conversion of these two chimeric genes. ..
  8. Barbaro M, Lajic S, Baldazzi L, Balsamo A, Pirazzoli P, Cicognani A, et al. Functional analysis of two recurrent amino acid substitutions in the CYP21 gene from Italian patients with congenital adrenal hyperplasia. J Clin Endocrinol Metab. 2004;89:2402-7 pubmed
    ..This impairment of activity was confirmed in vivo by detection of heterozygote carriers by the ACTH test. ..
  9. Menassa R, Tardy V, Despert F, Bouvattier Morel C, Brossier J, Cartigny M, et al. p.H62L, a rare mutation of the CYP21 gene identified in two forms of 21-hydroxylase deficiency. J Clin Endocrinol Metab. 2008;93:1901-8 pubmed publisher
    ..According to phenotype and functional studies, p.H62L is a mild mutation, responsible for a more severe phenotype when associated with another mild mutation. These data are important for patient management and genetic counseling. ..
  10. Lee H, Lee Y, Lin C. PCR-based detection of the CYP21 deletion and TNXA/TNXB hybrid in the RCCX module. Genomics. 2004;83:944-50 pubmed
    ..This rapid, nonradioactive detection method will be beneficial for diagnostic purposes that are limited to the population originally studied. ..
  11. Lee H, Chang S, Lee Y, Raskin S, Lin S, Chao M, et al. Deletion of the C4-CYP21 repeat module leading to the formation of a chimeric CYP21P/CYP21 gene in a 9.3-kb fragment as a cause of steroid 21-hydroxylase deficiency. Clin Chem. 2003;49:319-22 pubmed
  12. Speiser P. Nonclassic adrenal hyperplasia. Rev Endocr Metab Disord. 2009;10:77-82 pubmed publisher
    ..This article will review relevant clinical, hormonal and genetic aspects of nonclassic adrenal hyperplasia. ..
  13. Torresani T, Biason Lauber A. Congenital adrenal hyperplasia: diagnostic advances. J Inherit Metab Dis. 2007;30:563-75 pubmed
    ..This discussion will be limited to the most common form of congenital adrenal hyperplasia, with focus on the diagnostic advances in this disease. ..
  14. Parajes S, Quinterio C, Dominguez F, Loidi L. A simple and robust quantitative PCR assay to determine CYP21A2 gene dose in the diagnosis of 21-hydroxylase deficiency. Clin Chem. 2007;53:1577-84 pubmed
    ..This method together with CYP21A2 gene sequencing can provide a definitive system for the detection of almost all, common as well as rare, 21OHD alleles. ..
  15. Lee H. The chimeric CYP21P/CYP21 gene and 21-hydroxylase deficiency. J Hum Genet. 2004;49:65-72 pubmed
  16. Koppens P, Hoogenboezem T, Degenhart H. Duplication of the CYP21A2 gene complicates mutation analysis of steroid 21-hydroxylase deficiency: characteristics of three unusual haplotypes. Hum Genet. 2002;111:405-10 pubmed
  17. Janner M, Pandey A, Mullis P, Flück C. Clinical and biochemical description of a novel CYP21A2 gene mutation 962_963insA using a new 3D model for the P450c21 protein. Eur J Endocrinol. 2006;155:143-51 pubmed
    ..Our model will help in analyzing the genotype-phenotype relationship of P450c21 mutations which have not been tested for their functional activity in an in vitro assay. ..
  18. Riepe F, Hiort O, Grötzinger J, Sippell W, Krone N, Holterhus P. Functional and structural consequences of a novel point mutation in the CYP21A2 gene causing congenital adrenal hyperplasia: potential relevance of helix C for P450 oxidoreductase-21-hydroxylase interaction. J Clin Endocrinol Metab. 2008;93:2891-5 pubmed publisher
    ..Our data exemplify how the combination of in vitro expression and structural protein analysis provide novel insights into molecular mechanisms of reduced CYP21 activity, eventually explaining the patient's phenotype. ..
  19. Araújo R, Mendonca B, Barbosa A, Lin C, Marcondes J, Billerbeck A, et al. Microconversion between CYP21A2 and CYP21A1P promoter regions causes the nonclassical form of 21-hydroxylase deficiency. J Clin Endocrinol Metab. 2007;92:4028-34 pubmed
    ..Microconversions between CYP21A2 and CYP21A1P promoters could be involved in the nonclassical phenotype. Therefore CYP21A2 promoter analysis should be included in genetic studies of 21OHD. ..
  20. Lee H, Tsai F, Lee Y, Yang Y. Diversity of the CYP21A2 gene: a 6.2-kb TaqI fragment and a 3.2-kb TaqI fragment mistaken as CYP21A1P. Mol Genet Metab. 2006;88:372-7 pubmed
    ..Therefore, the CYP21A2 haplotype not only presents a 3.7-kb TaqI fragment but also may possibly exist in multiple forms including both 6.2- and 3.2-kb fragments. ..
  21. Keen Kim D, Redman J, Alanes R, Eachus M, Wilson R, New M, et al. Validation and clinical application of a locus-specific polymerase chain reaction- and minisequencing-based assay for congenital adrenal hyperplasia (21-hydroxylase deficiency). J Mol Diagn. 2005;7:236-46 pubmed
    ..Results from 102 clinical samples demonstrate that this assay is a rapid, reliable, and robust method for locus-specific identification of mutations and is suitable for routine clinical use and prenatal diagnosis. ..
  22. Lee H. Diversity of the CYP21P-like gene in CYP21 deficiency. DNA Cell Biol. 2005;24:1-9 pubmed
    ..Most of these gene arrangements probably exist in the C4A-XCYP21-TNXB and C4A-CYP21P/CYP21-TNXB gene loci. The existence of the C4A-CYP21P-TNXA/TNXB locus might not be common in CAH patients with 21-hydroxylase deficiency. ..
  23. New M. Extensive clinical experience: nonclassical 21-hydroxylase deficiency. J Clin Endocrinol Metab. 2006;91:4205-14 pubmed
    ..The signs and symptoms of hyperandrogenism are reversed with dexamethasone treatment. ..
  24. Koppens P, Smeets H, de Wijs I, Degenhart H. Mapping of a de novo unequal crossover causing a deletion of the steroid 21-hydroxylase (CYP21A2) gene and a non-functional hybrid tenascin-X (TNXB) gene. J Med Genet. 2003;40:e53 pubmed
  25. Soardi F, Barbaro M, Lau I, Lemos Marini S, Baptista M, Guerra Junior G, et al. Inhibition of CYP21A2 enzyme activity caused by novel missense mutations identified in Brazilian and Scandinavian patients. J Clin Endocrinol Metab. 2008;93:2416-20 pubmed publisher
    ..G56R, p.L107R, and p.L142P are reported for the first time. Most probably these novel mutations are closer to null than the p.I172N, but for the p.G56R, that might not be the case, and the p.H62L is definitely a nonclassical mutation. ..
  26. Guerra Junior G, Grumach A, de Lemos Marini S, Kirschfink M, Condino Neto A, de Araujo M, et al. Complement 4 phenotypes and genotypes in Brazilian patients with classical 21-hydroxylase deficiency. Clin Exp Immunol. 2009;155:182-8 pubmed publisher
    ..Considering this redundant gene cluster, C4 seems to be a well-protected gene segment along the evolutionary process. ..
  27. Barbaro M, Baldazzi L, Balsamo A, Lajic S, Robins T, Barp L, et al. Functional studies of two novel and two rare mutations in the 21-hydroxylase gene. J Mol Med (Berl). 2006;84:521-8 pubmed
    ..All four mutations are, thus, associated with severe enzyme deficiency and are predicted to cause classic CAH if found in trans with other mutations causing severe enzyme deficiency. ..
  28. Krone N, Riepe F, Grötzinger J, Partsch C, Sippell W. Functional characterization of two novel point mutations in the CYP21 gene causing simple virilizing forms of congenital adrenal hyperplasia due to 21-hydroxylase deficiency. J Clin Endocrinol Metab. 2005;90:445-54 pubmed
    ..Studying the enzyme function in vitro helps to understand the phenotypical expression and disease severity of 21-hydroxylase deficiency and also provides new insights into cytochrome P450 structure-function relationships. ..
  29. Baumgartner Parzer S, Nowotny P, Heinze G, Waldhausl W, Vierhapper H. Carrier frequency of congenital adrenal hyperplasia (21-hydroxylase deficiency) in a middle European population. J Clin Endocrinol Metab. 2005;90:775-8 pubmed
    ..In conclusion, the observed CAH carrier frequency of 9.5% suggests a higher prevalence of CAH heterozygosity in a middle European population than hitherto estimated independently of the individuals' Yugoslav or non-Yugoslav origin. ..
  30. White P, Vitek A, Dupont B, New M. Characterization of frequent deletions causing steroid 21-hydroxylase deficiency. Proc Natl Acad Sci U S A. 1988;85:4436-40 pubmed
    ..Thus, gene conversions are rarely confused with deletions as a cause of 21-hydroxylase deficiency. ..
  31. Yu C. The complete exon-intron structure of a human complement component C4A gene. DNA sequences, polymorphism, and linkage to the 21-hydroxylase gene. J Immunol. 1991;146:1057-66 pubmed
    ..A PvuII restriction length polymorphism has been detected within the region of DNA coding for C4a. The intergenic region between C4 and the neighboring 21-hydroxylase gene, CYP21, is approximately 3028 bp in size. ..
  32. Speiser P, Dupont J, Zhu D, Serrat J, Buegeleisen M, Tusie Luna M, et al. Disease expression and molecular genotype in congenital adrenal hyperplasia due to 21-hydroxylase deficiency. J Clin Invest. 1992;90:584-95 pubmed
    ..These data suggest that most but not all of the phenotypic variability in 21-hydroxylase deficiency results from allelic variation in CYP21. Accurate prenatal diagnosis should be possible in most cases using the described strategy. ..
  33. Billerbeck A, Bachega T, Frazatto E, Nishi M, Goldberg A, Marin M, et al. A novel missense mutation, GLY424SER, in Brazilian patients with 21-hydroxylase deficiency. J Clin Endocrinol Metab. 1999;84:2870-2 pubmed
    ..Search for the G424S mutation in other populations will reveal whether it is restricted to the Brazilian patients or if it has a wider ethnic distribution. ..
  34. White P, New M, Dupont B. Structure of human steroid 21-hydroxylase genes. Proc Natl Acad Sci U S A. 1986;83:5111-5 pubmed
    ..A second frameshift and a nonsense mutation occur downstream. In contrast, the sequence of the exons of the B gene is identical to the cDNA sequence. The 21-OHase A gene is, therefore, a pseudogene. ..
  35. Koppens P, Hoogenboezem T, Degenhart H. CYP21 and CYP21P variability in steroid 21-hydroxylase deficiency patients and in the general population in the Netherlands. Eur J Hum Genet. 2000;8:827-36 pubmed
    ..Apparent 'large-scale' CYP21-CYP21P gene conversions lead to hybrid genes that are very similar to those found in CYP21 deletions, so these haplotypes have probably resulted from a meiotic double unequal crossover. ..
  36. Deneux C, Tardy V, Dib A, Mornet E, Billaud L, Charron D, et al. Phenotype-genotype correlation in 56 women with nonclassical congenital adrenal hyperplasia due to 21-hydroxylase deficiency. J Clin Endocrinol Metab. 2001;86:207-13 pubmed
    ..Therefore, the phenotype cannot be accurately predicted from the genotype. Variability in phenotypic expression may be conditioned by mechanisms other than genetic heterogeneity at the CYP21 locus. ..
  37. Rupert K, Rennebohm R, Yu C. An unequal crossover between the RCCX modules of the human MHC leading to the presence of a CYP21B gene and a tenascin TNXB/TNXA-RP2 recombinant between C4A and C4B genes in a patient with juvenile rheumatoid arthritis. Exp Clin Immunogenet. 1999;16:81-97 pubmed
    ..Elucidation of the breakpoint region provides further evidence for the instability of the MHC class III gene region as a result of the RCCX modular variation. ..
  38. Shen L, Wu L, Sanlioglu S, Chen R, Mendoza A, Dangel A, et al. Structure and genetics of the partially duplicated gene RP located immediately upstream of the complement C4A and the C4B genes in the HLA class III region. Molecular cloning, exon-intron structure, composite retroposon, and breakpoint of gene duplic. J Biol Chem. 1994;269:8466-76 pubmed
    ..Duplication of the RCCX modules probably occurred before the speciation of great apes and humans as they contain the same breakpoint region of RP and Gene X gene duplication. ..
  39. Lee H. CYP21 mutations and congenital adrenal hyperplasia. Clin Genet. 2001;59:293-301 pubmed
  40. Blanchong C, Zhou B, Rupert K, Chung E, Jones K, Sotos J, et al. Deficiencies of human complement component C4A and C4B and heterozygosity in length variants of RP-C4-CYP21-TNX (RCCX) modules in caucasians. The load of RCCX genetic diversity on major histocompatibility complex-associated disease. J Exp Med. 2000;191:2183-96 pubmed
  41. Higashi Y, Tanae A, Inoue H, Fujii Kuriyama Y. Evidence for frequent gene conversion in the steroid 21-hydroxylase P-450(C21) gene: implications for steroid 21-hydroxylase deficiency. Am J Hum Genet. 1988;42:17-25 pubmed
    ..2-kb TaqI fragment) whereas that of the B gene (the 3.7-kb TaqI fragment) was relatively constant at two or three copies. ..
  42. New M, Wilson R. Steroid disorders in children: congenital adrenal hyperplasia and apparent mineralocorticoid excess. Proc Natl Acad Sci U S A. 1999;96:12790-7 pubmed
    ..In 1998, we reported a mild form of this disease, which may represent an important cause of low-renin hypertension. ..
  43. Higashi Y, Yoshioka H, Yamane M, Gotoh O, Fujii Kuriyama Y. Complete nucleotide sequence of two steroid 21-hydroxylase genes tandemly arranged in human chromosome: a pseudogene and a genuine gene. Proc Natl Acad Sci U S A. 1986;83:2841-5 pubmed
    ..Tandem arrangement of the highly homologous pseudo- and genuine genes in close proximity could account for the high incidence of P-450(C21) gene deficiency by homologous gene recombination. ..
  44. Chu X, Braun Heimer L, Rittner C, Schneider P. Identification of the recombination site within the steroid 21-hydroxylase gene (CYP21) of the HLA-B47,DR7 haplotype. Exp Clin Immunogenet. 1992;9:80-5 pubmed
    ..The findings were confirmed by PCR amplification of a 1.8-kb fragment of the CYP21 gene. This PCR system is specific for CYP21A/B recombinant genes and may be used for screening among CAH patients carrying this type of deletion. ..
  45. Lee H, Chang J, Tsai C, Tsai F, Chao H, Chung B. Analysis of the chimeric CYP21P/CYP21 gene in steroid 21-hydroxylase deficiency. Clin Chem. 2000;46:606-11 pubmed
    ..Therefore, our new PCR-based assay is a more effective way to analyze congenital adrenal hyperplasia mutations. ..
  46. Krone N, Braun A, Roscher A, Schwarz H. A novel frameshift mutation (141delT) in exon 1 of the 21-hydroxylase gene (CYP21) in a patient with the salt wasting form of congenital adrenal hyperplasia. Mutation in brief no. 255. Online. Hum Mutat. 1999;14:90-1 pubmed
    ..This novel mutation has not been reported to occur in the CYP21P alleles and it was not found in the CYP21P alleles in this CAH family. ..
  47. Lee H, Chao H, Lee Y, Shu S, Chao M, Kuo J, et al. Identification of four novel mutations in the CYP21 gene in congenital adrenal hyperplasia in the Chinese. Hum Genet. 1998;103:304-10 pubmed
    ..Since these mutations are not found in the neighboring CYP21P pseudogene, gene conversion should not be the cause of these novel mutations. ..
  48. Wedell A, Luthman H. Steroid 21-hydroxylase (P450c21): a new allele and spread of mutations through the pseudogene. Hum Genet. 1993;91:236-40 pubmed
    ..Thus, also rare mutations can spread via the pseudogene and can therefore be expected to arise independently in unrelated individuals. ..
  49. Mornet E, Crété P, Kuttenn F, Raux Demay M, Boue J, White P, et al. Distribution of deletions and seven point mutations on CYP21B genes in three clinical forms of steroid 21-hydroxylase deficiency. Am J Hum Genet. 1991;48:79-88 pubmed
  50. Wedell A, Thilen A, Ritzen E, Stengler B, Luthman H. Mutational spectrum of the steroid 21-hydroxylase gene in Sweden: implications for genetic diagnosis and association with disease manifestation. J Clin Endocrinol Metab. 1994;78:1145-52 pubmed
  51. Yang Z, Mendoza A, Welch T, Zipf W, Yu C. Modular variations of the human major histocompatibility complex class III genes for serine/threonine kinase RP, complement component C4, steroid 21-hydroxylase CYP21, and tenascin TNX (the RCCX module). A mechanism for gene deletions and disease ass. J Biol Chem. 1999;274:12147-56 pubmed
    ..Elucidation of the DNA sequence for the recombination breakpoint region and sequence analyses yielded definitive proof for an unequal crossover between TNXA from a bimodular chromosome and TNXB from a monomodular chromosome. ..
  52. Donohoue P, Guethlein L, Collins M, Van Dop C, Migeon C, Bias W, et al. The HLA-A3, Cw6,B47,DR7 extended haplotypes in salt losing 21-hydroxylase deficiency and in the Old Order Amish: identical class I antigens and class II alleles with at least two crossover sites in the class III region. Tissue Antigens. 1995;46:163-72 pubmed
    ..A model is proposed which accounts for the CAH-linked mutant haplotype arising from a nonmutant homologue via three crossings-over. ..
  53. Wedell A, Luthman H. Steroid 21-hydroxylase deficiency: two additional mutations in salt-wasting disease and rapid screening of disease-causing mutations. Hum Mol Genet. 1993;2:499-504 pubmed
    ..Allele-specific PCR was established also for these mutations and used to screen for their presence in the pseudogene. However, the two novel mutations were not found in at least 34 pseudogenes. ..