LETTERS:
PUBLISHED
Novel Compound Heterozygous Mutations in PRKRA Cause Pure Dystonia We read with interest the paper by Zech et al.,1 in which they report a new European dystonia family with a homozygous PRKRA mutation. Our group recently identified a new Brazilian family with compound heterozygous variants in PRKRA and a pure dystonia phenotype of variable severity. The proband is a 37-year-old Brazilian woman of Portuguese ancestry, the fifth child of non-consanguineous parents, who was first assessed at age 8 reporting a history of dystonia since age 4. Birth history was uneventful and, except for speech delay, development milestones were normal until age 4. Dystonia onset was in the right upper limb and generalized in 4 years, with severe involvement of cervical region, trunk, and limbs, but mild dysarthria and dysphonia. No parkinsonian or pyramidal signs were observed. Laboratory screening for Wilson’s disease was negative and brain image at ages 8 and 16 were normal. She was not responsive to levodopa, and response to anticholinergic drugs was poor. At first, family history of dystonia was negative. Among her five siblings, three were healthy and two were deceased (one from pertussis at 8 mo, and another from unknown causes at 1 mo). At age 23 she was enrolled in a genetic study of dystonia, and screening for TOR1A and THAP1 was negative.2 At that time, both parents and three siblings were examined by movement disorders specialists. Her younger sister, aged 19, had a very subtle dystonic posture in the third and fourth fingers of the left hand and was rated as possible dystonia. She was not aware of the age of onset. At age 28 she developed cervical dystonia and marked dysphonia. When the sibling became affected, the family history was consistent with possible recessive inheritance, which in turn, led us to screen PRKRA using Sanger sequencing. In both affected patients, we identified novel variants in exon 2, c.G230C (p.Cys77Ser), and in exon 7, c.G638T (p.Cys213Phe). The first is in the DRBM1 functional domain. A variant affecting the same amino acid c.T637C (p.Cys213Arg), together with c.C665T (p.Pro222Leu), has
ARTICLE
been previously described in a patient with dystonia, whose symptoms developed after a febrile illness and who had volume loss in the basal ganglia.3 All unaffected family members carry a single variant. The father and two siblings carry the c.G230C variant; the mother carries c.G638T. None of these variants was found in 240 Brazilian control chromosomes, and only p.Cys213Phe was reported at an extremely low frequency (7.916e-06) in the Exome Aggregation Consortium (ExAC) (http://exac.broadinstitute.org). Three of four in silico predictions support these variants as disease causing (Table 1). Both variants are highly conserved. Since PRKRA was first identified as a dystonia cause,4 only three other families/individuals have been found with mutations.1,3,5 The Brazilian and Polish families with the p.Pro222Leu variant share a dystonia-parkinsonism phenotype and the disease haplotype that could represent a founder mutation.1 Herein we report two novel mutations in siblings with isolated dystonia, confirming PRKRA as a causative disease gene. Moreover, we suggest that PRKRA mutations may be a more widespread cause of generalized dystonia, and screening should be considered in familial cases with putative autosomal recessive inheritance. Patricia de Carvalho Aguiar, MD, PhD,*1,2 Vanderci Borges, MD, PhD,2 Henrique Ballalai Ferraz, MD, PhD,2 and Laurie Jean Ozelius, PhD3 1 Hospital Israelita Albert Einstein, Sao Paulo, SP, Brazil 2 Universidade Federal de Sao Paulo, Department of Neurology and Neurosurgery, Sao Paulo, SP, Brazil 3 Genetics and Genomic Sciences and Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA Acknowledgments: We thank Amber Clark-Nobles for technical help, Liliane Santana Oliveira for help with CADD scores analysis, as well as the Exome Aggregation Consortium and the groups that provided exome variant data for comparison. A full list of contributing groups can be found at http://exac.broadinstitute.org/ about.
References 1.
Zech M, Castrop F, Schormair B, et al. DYT16 revisited: Exome sequencing identifies PRKRA mutations in a European dystonia family. Mov Disord 2014;29:1504-1510.
2.
De Carvalho Aguiar P, Fuchs T, Borges V, Lamar KM, Silva SM, Ferraz HB, Ozelius L. Screening of Brazilian families with primary dystonia reveals a novel THAP1 mutation and a de novo TOR1A GAG deletion. Mov Disord 2010;25:2854-2857.
3.
Lemmon ME, Lavenstein B, Applegate CD, Hamosh A, Tekes A, Singer HS. A novel presentation of DYT 16: acute onset in infancy and association with MRI abnormalities. Mov Disord 2013;28: 1937-1938.
Relevant conflicts of interest/financial disclosures: Nothing to report. Full financial disclosures and author roles may be found in the online version of this article.
4.
Camargos S, Scholz S, Sim on-S anchez J, et al. DYT16, a novel young-onset dystonia-parkinsonism disorder: identification of a segregating mutation in the stress-response protein PRKRA. Lancet Neurol 2008;7:207-215.
Received: 5 November 2014; Revised: 24 December 2014; Accepted: 8 January 2015 Published online 4 March 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/mds.26175
5.
Seibler P, Djarmati A, Langpap B, et al. A heterozygous frameshift mutation in PRKRA (DYT16) associated with generalised dystonia in a German patient. Lancet Neurol 2008;7:380381.
-----------------------------------------------------------Correspondence to: Dr. Patricia de Carvalho Aguiar, Hospital Israelita ~o Paulo-SP, Albert Einstein Bloco A 2ss IIEP Av. Albert Einstein, 627 Sa Brazil 05652-901, e-mail: [email protected] Funding agencies: This study was supported by Sao Paulo Research Foundation (FAPESP) grant #2010/19206-0 (PA) and NS037409 (LJO).
Movement Disorders, Vol. 30, No. 6, 2015
877
L E T T E R S :
P U B L I S H E D
A R T I C L E
TABLE 1. In silico analysis and frequency of PRKRA variants Algorithm (Score/ Prediction) Variant
c.G230C/p.C77S c.G638T/p.C213F c.T637C/ p.C213R3 c. C665T/ p.P222L1,3,4
Frequency*
PolyPhen2
Mutation Taster
SIFT
CADD
Overall
European
0.619/Possibly damaging 0.902/Possibly damaging 0.009/Benign 0.001/Benign
112/Disease causing 112/Disease causing 180/Disease causing 98/Disease causing
0.46/Tolerated 0.12/Tolerated 0.12/Tolerated 0.07/Tolerated
23.1/Deleterious 22.3/Deleterious 20.2/Deleterious 21.3/Deleterious
0 7.916e-06 0 1.453e-04
0 1.454e-05 0 1.453e-04
*Frequency data from 63,000 exomes at Exome Aggregation Consortium (ExAC), Cambridge, MA (http://exac.broadinstitute.org) [accessed 2014 October 31st].
Reply to Letter: Novel Compound Heterozygous Mutations in PRKRA Cause Pure Dystonia
We thank Dr. de Carvalho Aguiar and colleagues for their insightful letter entitled “Novel compound heterozygous mutations in PRKRA cause pure dystonia,“ which revisits our recent article on recessively transmitted DYT16 dystonia.1 The authors used Sanger sequencing to uncover novel compound heterozygous PRKRA variants (c.230G>C [p.Cys77Ser]; c.638G>T [p.Cys213Phe]) in 2 female siblings of a nonconsanguineous Brazilian family presenting an earlyonset isolated dystonia phenotype. In our article, we described a consanguineous Polish sibpair affected by adolescence onset dystonia-parkinsonism, who harbored the recurrent homozygous PRKRA c.665C>T (p.Pro222Leu) mutation within a 1.2-Mb spanning disease haplotype shared with three DYT16 families of Brazilian origin.2 Now, the identification of independent disease-segregating PRKRA mutations in familial dystonia rules out the possibility that the original c.665C>T (p.Pro222Leu) variant only represents an innocuous tag single-nucleotide polymorphism, which is in linkage disequilibrium with the real causative sequence alteration borne on the common haplotype. Hence, the study by de Carvalho Aguiar and colleagues finally proves that PRKRA coding region mutations are indeed the underlying genetic defect in DYT16. Considered with another recent article reporting compound heterozygous PRKRA variants (c.665C>T [p.Pro222Leu]; c.637T>C [p.Cys213Arg]) in a sporadic infant manifesting dystonia-parkinsonism in the setting of a febrile illness,3 to date, a total of four different PRKRA missense substitutions affecting distinct parts of the
------------------------------------------------------------
Correspondence to: Prof. Dr. Juliane Winkelmann, Department of Neurology and Neurological Sciences and Center for Sleep Sciences and Medicine, 3165 Porter Drive, Palo Alto, CA 94301, USA; [email protected] Relevant conflicts of interest/financial disclosures: Nothing to report. Full financial disclosures and author roles may be found in the online version of this article. Received: 9 March 2015; Accepted: 11 March 2015 Published online 25 April 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/mds.26233
878
Movement Disorders, Vol. 30, No. 6, 2015
encoded protein have been clearly implicated in DYT16. All of these appear to be either extremely rare or private, as evidenced by recently released exome data from the Exome Aggregation Consortium (ExAC),4 and only the c.665C>T (p.Pro222Leu) variant seems to occur in diverse ethnicities (prevalence according to ExAC: 1:3336 in Europeans, 1:2575 in African Americans, and 1:964 in Latinos).4 De Carvalho Aguiar and colleagues applied four different bioinformatics algorithms (PolyPhen2, SIFT, Mutation taster, and CADD) to assess the possible damaging nature of the DYT16-associated PRKRA variants and found at least one benign prediction for each variant, indicating the limited accuracy of some of these in silico tools. On the clinical level, the growing number of molecularly confirmed DYT16 cases highlights phenotypic heterogeneity, ranging from severe infantile combined dystonia syndromes to moderate adolescence onset isolated dystonia (Table 1). Also, remarkable intrafamilial variability is observed, suggesting that additional genetic or environmental disease modifiers may exist in DYT16. The most common clinical expression might be one of early-onset generalized dystonia in combination with varying degrees of parkinsonism, mandating comprehensive PRKRA genetic screening in such cases, particularly within a familial context suggestive of recessive disease transmission. Moreover, functional studies should be the logical consequence to provide insight as to how PRKRA gene mutations mediate the phenotypic effect and to develop therapeutic strategies for this debilitating condition. Autosomal-recessively inherited isolated dystonia phenotypes might be more common than previously appreciated.
Michael Zech, MD,1,2 Florian Castrop, MD,3 Bernhard Haslinger, MD,1 and Juliane Winkelmann, MD1,2,4,5* 1 Neurologische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universit€at M€ unchen, Munich, Germany 2 Institut f€ ur Humangenetik, Helmholtz Zentrum M€ unchen, Munich, Germany 3
Asklepios Stadtklinik Bad T€ olz, Bad T€ olz, Germany
4
Department of Neurology and Neurological Sciences and Center for Sleep Sciences and Medicine, Stanford University School of Medicine, Palo Alto, California, USA 5
Munich Cluster for Systems Neurology, SyNergy, Munich, Germany
PUBLISHED
Novel Compound Heterozygous Mutations in PRKRA Cause Pure Dystonia We read with interest the paper by Zech et al.,1 in which they report a new European dystonia family with a homozygous PRKRA mutation. Our group recently identified a new Brazilian family with compound heterozygous variants in PRKRA and a pure dystonia phenotype of variable severity. The proband is a 37-year-old Brazilian woman of Portuguese ancestry, the fifth child of non-consanguineous parents, who was first assessed at age 8 reporting a history of dystonia since age 4. Birth history was uneventful and, except for speech delay, development milestones were normal until age 4. Dystonia onset was in the right upper limb and generalized in 4 years, with severe involvement of cervical region, trunk, and limbs, but mild dysarthria and dysphonia. No parkinsonian or pyramidal signs were observed. Laboratory screening for Wilson’s disease was negative and brain image at ages 8 and 16 were normal. She was not responsive to levodopa, and response to anticholinergic drugs was poor. At first, family history of dystonia was negative. Among her five siblings, three were healthy and two were deceased (one from pertussis at 8 mo, and another from unknown causes at 1 mo). At age 23 she was enrolled in a genetic study of dystonia, and screening for TOR1A and THAP1 was negative.2 At that time, both parents and three siblings were examined by movement disorders specialists. Her younger sister, aged 19, had a very subtle dystonic posture in the third and fourth fingers of the left hand and was rated as possible dystonia. She was not aware of the age of onset. At age 28 she developed cervical dystonia and marked dysphonia. When the sibling became affected, the family history was consistent with possible recessive inheritance, which in turn, led us to screen PRKRA using Sanger sequencing. In both affected patients, we identified novel variants in exon 2, c.G230C (p.Cys77Ser), and in exon 7, c.G638T (p.Cys213Phe). The first is in the DRBM1 functional domain. A variant affecting the same amino acid c.T637C (p.Cys213Arg), together with c.C665T (p.Pro222Leu), has
ARTICLE
been previously described in a patient with dystonia, whose symptoms developed after a febrile illness and who had volume loss in the basal ganglia.3 All unaffected family members carry a single variant. The father and two siblings carry the c.G230C variant; the mother carries c.G638T. None of these variants was found in 240 Brazilian control chromosomes, and only p.Cys213Phe was reported at an extremely low frequency (7.916e-06) in the Exome Aggregation Consortium (ExAC) (http://exac.broadinstitute.org). Three of four in silico predictions support these variants as disease causing (Table 1). Both variants are highly conserved. Since PRKRA was first identified as a dystonia cause,4 only three other families/individuals have been found with mutations.1,3,5 The Brazilian and Polish families with the p.Pro222Leu variant share a dystonia-parkinsonism phenotype and the disease haplotype that could represent a founder mutation.1 Herein we report two novel mutations in siblings with isolated dystonia, confirming PRKRA as a causative disease gene. Moreover, we suggest that PRKRA mutations may be a more widespread cause of generalized dystonia, and screening should be considered in familial cases with putative autosomal recessive inheritance. Patricia de Carvalho Aguiar, MD, PhD,*1,2 Vanderci Borges, MD, PhD,2 Henrique Ballalai Ferraz, MD, PhD,2 and Laurie Jean Ozelius, PhD3 1 Hospital Israelita Albert Einstein, Sao Paulo, SP, Brazil 2 Universidade Federal de Sao Paulo, Department of Neurology and Neurosurgery, Sao Paulo, SP, Brazil 3 Genetics and Genomic Sciences and Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA Acknowledgments: We thank Amber Clark-Nobles for technical help, Liliane Santana Oliveira for help with CADD scores analysis, as well as the Exome Aggregation Consortium and the groups that provided exome variant data for comparison. A full list of contributing groups can be found at http://exac.broadinstitute.org/ about.
References 1.
Zech M, Castrop F, Schormair B, et al. DYT16 revisited: Exome sequencing identifies PRKRA mutations in a European dystonia family. Mov Disord 2014;29:1504-1510.
2.
De Carvalho Aguiar P, Fuchs T, Borges V, Lamar KM, Silva SM, Ferraz HB, Ozelius L. Screening of Brazilian families with primary dystonia reveals a novel THAP1 mutation and a de novo TOR1A GAG deletion. Mov Disord 2010;25:2854-2857.
3.
Lemmon ME, Lavenstein B, Applegate CD, Hamosh A, Tekes A, Singer HS. A novel presentation of DYT 16: acute onset in infancy and association with MRI abnormalities. Mov Disord 2013;28: 1937-1938.
Relevant conflicts of interest/financial disclosures: Nothing to report. Full financial disclosures and author roles may be found in the online version of this article.
4.
Camargos S, Scholz S, Sim on-S anchez J, et al. DYT16, a novel young-onset dystonia-parkinsonism disorder: identification of a segregating mutation in the stress-response protein PRKRA. Lancet Neurol 2008;7:207-215.
Received: 5 November 2014; Revised: 24 December 2014; Accepted: 8 January 2015 Published online 4 March 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/mds.26175
5.
Seibler P, Djarmati A, Langpap B, et al. A heterozygous frameshift mutation in PRKRA (DYT16) associated with generalised dystonia in a German patient. Lancet Neurol 2008;7:380381.
-----------------------------------------------------------Correspondence to: Dr. Patricia de Carvalho Aguiar, Hospital Israelita ~o Paulo-SP, Albert Einstein Bloco A 2ss IIEP Av. Albert Einstein, 627 Sa Brazil 05652-901, e-mail: [email protected] Funding agencies: This study was supported by Sao Paulo Research Foundation (FAPESP) grant #2010/19206-0 (PA) and NS037409 (LJO).
Movement Disorders, Vol. 30, No. 6, 2015
877
L E T T E R S :
P U B L I S H E D
A R T I C L E
TABLE 1. In silico analysis and frequency of PRKRA variants Algorithm (Score/ Prediction) Variant
c.G230C/p.C77S c.G638T/p.C213F c.T637C/ p.C213R3 c. C665T/ p.P222L1,3,4
Frequency*
PolyPhen2
Mutation Taster
SIFT
CADD
Overall
European
0.619/Possibly damaging 0.902/Possibly damaging 0.009/Benign 0.001/Benign
112/Disease causing 112/Disease causing 180/Disease causing 98/Disease causing
0.46/Tolerated 0.12/Tolerated 0.12/Tolerated 0.07/Tolerated
23.1/Deleterious 22.3/Deleterious 20.2/Deleterious 21.3/Deleterious
0 7.916e-06 0 1.453e-04
0 1.454e-05 0 1.453e-04
*Frequency data from 63,000 exomes at Exome Aggregation Consortium (ExAC), Cambridge, MA (http://exac.broadinstitute.org) [accessed 2014 October 31st].
Reply to Letter: Novel Compound Heterozygous Mutations in PRKRA Cause Pure Dystonia
We thank Dr. de Carvalho Aguiar and colleagues for their insightful letter entitled “Novel compound heterozygous mutations in PRKRA cause pure dystonia,“ which revisits our recent article on recessively transmitted DYT16 dystonia.1 The authors used Sanger sequencing to uncover novel compound heterozygous PRKRA variants (c.230G>C [p.Cys77Ser]; c.638G>T [p.Cys213Phe]) in 2 female siblings of a nonconsanguineous Brazilian family presenting an earlyonset isolated dystonia phenotype. In our article, we described a consanguineous Polish sibpair affected by adolescence onset dystonia-parkinsonism, who harbored the recurrent homozygous PRKRA c.665C>T (p.Pro222Leu) mutation within a 1.2-Mb spanning disease haplotype shared with three DYT16 families of Brazilian origin.2 Now, the identification of independent disease-segregating PRKRA mutations in familial dystonia rules out the possibility that the original c.665C>T (p.Pro222Leu) variant only represents an innocuous tag single-nucleotide polymorphism, which is in linkage disequilibrium with the real causative sequence alteration borne on the common haplotype. Hence, the study by de Carvalho Aguiar and colleagues finally proves that PRKRA coding region mutations are indeed the underlying genetic defect in DYT16. Considered with another recent article reporting compound heterozygous PRKRA variants (c.665C>T [p.Pro222Leu]; c.637T>C [p.Cys213Arg]) in a sporadic infant manifesting dystonia-parkinsonism in the setting of a febrile illness,3 to date, a total of four different PRKRA missense substitutions affecting distinct parts of the
------------------------------------------------------------
Correspondence to: Prof. Dr. Juliane Winkelmann, Department of Neurology and Neurological Sciences and Center for Sleep Sciences and Medicine, 3165 Porter Drive, Palo Alto, CA 94301, USA; [email protected] Relevant conflicts of interest/financial disclosures: Nothing to report. Full financial disclosures and author roles may be found in the online version of this article. Received: 9 March 2015; Accepted: 11 March 2015 Published online 25 April 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/mds.26233
878
Movement Disorders, Vol. 30, No. 6, 2015
encoded protein have been clearly implicated in DYT16. All of these appear to be either extremely rare or private, as evidenced by recently released exome data from the Exome Aggregation Consortium (ExAC),4 and only the c.665C>T (p.Pro222Leu) variant seems to occur in diverse ethnicities (prevalence according to ExAC: 1:3336 in Europeans, 1:2575 in African Americans, and 1:964 in Latinos).4 De Carvalho Aguiar and colleagues applied four different bioinformatics algorithms (PolyPhen2, SIFT, Mutation taster, and CADD) to assess the possible damaging nature of the DYT16-associated PRKRA variants and found at least one benign prediction for each variant, indicating the limited accuracy of some of these in silico tools. On the clinical level, the growing number of molecularly confirmed DYT16 cases highlights phenotypic heterogeneity, ranging from severe infantile combined dystonia syndromes to moderate adolescence onset isolated dystonia (Table 1). Also, remarkable intrafamilial variability is observed, suggesting that additional genetic or environmental disease modifiers may exist in DYT16. The most common clinical expression might be one of early-onset generalized dystonia in combination with varying degrees of parkinsonism, mandating comprehensive PRKRA genetic screening in such cases, particularly within a familial context suggestive of recessive disease transmission. Moreover, functional studies should be the logical consequence to provide insight as to how PRKRA gene mutations mediate the phenotypic effect and to develop therapeutic strategies for this debilitating condition. Autosomal-recessively inherited isolated dystonia phenotypes might be more common than previously appreciated.
Michael Zech, MD,1,2 Florian Castrop, MD,3 Bernhard Haslinger, MD,1 and Juliane Winkelmann, MD1,2,4,5* 1 Neurologische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universit€at M€ unchen, Munich, Germany 2 Institut f€ ur Humangenetik, Helmholtz Zentrum M€ unchen, Munich, Germany 3
Asklepios Stadtklinik Bad T€ olz, Bad T€ olz, Germany
4
Department of Neurology and Neurological Sciences and Center for Sleep Sciences and Medicine, Stanford University School of Medicine, Palo Alto, California, USA 5
Munich Cluster for Systems Neurology, SyNergy, Munich, Germany
