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The RAB39B p.G192R mutation causes X-linked dominant Parkinson's disease.

Mata IF, Jang Y, Kim CH, Hanna DS, Dorschner MO, Samii A, Agarwal P, Roberts JW, Klepitskaya O, Shprecher DR, Chung KA, Factor SA, Espay AJ, Revilla FJ, Higgins DS, Litvan I, Leverenz JB, Yearout D, Inca-Martinez M, Martinez E, Thompson TR, Cholerton BA, Hu SC, Edwards KL, Kim KS, Zabetian CP - Mol Neurodegener (2015)

Bottom Line: We identified a missense mutation (c.574G > A; p.G192R) in the RAB39B gene that closely segregated with disease and exhibited X-linked dominant inheritance with reduced penetrance in females.Experiments in PC12 and SK-N-BE(2)C cells demonstrated that p.G192R resulted in mislocalization of the mutant protein, possibly by altering the structure of the hypervariable C-terminal domain which mediates intracellular targeting.Further characterization of normal and aberrant RAB39B function might elucidate important mechanisms underlying neurodegeneration in PD and related disorders.

View Article: PubMed Central - PubMed

Affiliation: Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA. nachofm@uw.edu.

ABSTRACT

Objective: To identify the causal gene in a multi-incident U.S. kindred with Parkinson's disease (PD).

Methods: We characterized a family with a classical PD phenotype in which 7 individuals (5 males and 2 females) were affected with a mean age at onset of 46.1 years (range, 29-57 years). We performed whole exome sequencing on 4 affected and 1 unaffected family members. Sanger-sequencing was then used to verify and genotype all candidate variants in the remainder of the pedigree. Cultured cells transfected with wild-type or mutant constructs were used to characterize proteins of interest.

Results: We identified a missense mutation (c.574G > A; p.G192R) in the RAB39B gene that closely segregated with disease and exhibited X-linked dominant inheritance with reduced penetrance in females. The mutation occurred in a highly conserved amino acid residue and was not observed among 87,725 X chromosomes in the Exome Aggregation Consortium dataset. Sequencing of the RAB39B coding region in 587 familial PD cases yielded two additional mutations (c.428C > G [p.A143G] and c.624_626delGAG [p.R209del]) that were predicted to be deleterious in silico but occurred in families that were not sufficiently informative to assess segregation with disease. Experiments in PC12 and SK-N-BE(2)C cells demonstrated that p.G192R resulted in mislocalization of the mutant protein, possibly by altering the structure of the hypervariable C-terminal domain which mediates intracellular targeting.

Conclusions: Our findings implicate RAB39B, an essential regulator of vesicular-trafficking, in clinically typical PD. Further characterization of normal and aberrant RAB39B function might elucidate important mechanisms underlying neurodegeneration in PD and related disorders.

No MeSH data available.


Related in: MedlinePlus

Identification of the RAB39B p.G192R mutation by whole exome sequencing in a multigenerational kindred with Parkinson’s disease. a Pedigree diagram; individuals affected with Parkinson’s disease are represented with black symbols, unaffected individuals with open symbols. Age at onset is indicated immediately below each symbol, followed by age at last clinical evaluation. Wt = wild type; Mut = mutation (p.G192R). b Multispecies protein sequence alignment. Hs = Homo sapiens; Mm = Mus musculus; Dr = Danio rerio (zebrafish); Dm = Drosophila melanogaster; Ce = Caenorhabditis elegans. c Predicted protein structure of RAB39B using Protein Homology/analogY Recognition Engine V 2.0 (Phyre2; http://www.sbg.bio.ic.ac.uk/phyre2/html/page.cgi?id=index) [23]; 89 % of the amino acid residues were modeled at >90 % confidence. P.G192R is located in the hypervariable C-terminal domain which is depicted in red
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Fig1: Identification of the RAB39B p.G192R mutation by whole exome sequencing in a multigenerational kindred with Parkinson’s disease. a Pedigree diagram; individuals affected with Parkinson’s disease are represented with black symbols, unaffected individuals with open symbols. Age at onset is indicated immediately below each symbol, followed by age at last clinical evaluation. Wt = wild type; Mut = mutation (p.G192R). b Multispecies protein sequence alignment. Hs = Homo sapiens; Mm = Mus musculus; Dr = Danio rerio (zebrafish); Dm = Drosophila melanogaster; Ce = Caenorhabditis elegans. c Predicted protein structure of RAB39B using Protein Homology/analogY Recognition Engine V 2.0 (Phyre2; http://www.sbg.bio.ic.ac.uk/phyre2/html/page.cgi?id=index) [23]; 89 % of the amino acid residues were modeled at >90 % confidence. P.G192R is located in the hypervariable C-terminal domain which is depicted in red

Mentions: We studied a U.S. family of European origin in which 7 individuals (5 males and 2 females) were affected and met UK PD Society Brain Bank clinical diagnostic criteria for PD [5] (Fig. 1a). The clinical characteristics of the affected family members are provided in Table 1. None of these individuals displayed atypical findings on neurological examination but two of them (III-15 and IV-4) had mild intellectual disability since childhood. DNA was available for 6 affected and 10 unaffected members of the family. We performed WES on 4 affected (III-4, III-9, III-11, and III-18) and 1 unaffected (III-13) family members. We filtered out all variants with a frequency >1 % in 515 controls from the NHLBI Exome Sequencing Project [6, 7] or that failed to meet the quality thresholds of the Genome Analysis ToolKit (GATK) “Best Practices” [8]. We identified three nonsynonymous variants that passed all filters, segregated with PD among the 5 individuals who underwent WES, and were confirmed by Sanger sequencing: USP1 c.573G > A (p.M191I), MVP c.2594G > T (p.G865V), and RAB39B c.574G > A (p.G192R) (Table 2). We then genotyped these three variants in all remaining family members and found that only RAB39B p.G192R was present in all six affected subjects. Furthermore, RAB39B p.G192R was not observed among 87,725 X chromosomes successfully sequenced for RAB39B in the Exome Aggregation Consortium database (ExAC; http://exac.broadinstitute.org). The amino acid G192 is highly conserved across species (Fig. 1b) and this mutation is predicted to be deleterious as evidenced by a Combined Annotation Dependent Depletion (CADD) [9] score of 29.4.Fig. 1


The RAB39B p.G192R mutation causes X-linked dominant Parkinson's disease.

Mata IF, Jang Y, Kim CH, Hanna DS, Dorschner MO, Samii A, Agarwal P, Roberts JW, Klepitskaya O, Shprecher DR, Chung KA, Factor SA, Espay AJ, Revilla FJ, Higgins DS, Litvan I, Leverenz JB, Yearout D, Inca-Martinez M, Martinez E, Thompson TR, Cholerton BA, Hu SC, Edwards KL, Kim KS, Zabetian CP - Mol Neurodegener (2015)

Identification of the RAB39B p.G192R mutation by whole exome sequencing in a multigenerational kindred with Parkinson’s disease. a Pedigree diagram; individuals affected with Parkinson’s disease are represented with black symbols, unaffected individuals with open symbols. Age at onset is indicated immediately below each symbol, followed by age at last clinical evaluation. Wt = wild type; Mut = mutation (p.G192R). b Multispecies protein sequence alignment. Hs = Homo sapiens; Mm = Mus musculus; Dr = Danio rerio (zebrafish); Dm = Drosophila melanogaster; Ce = Caenorhabditis elegans. c Predicted protein structure of RAB39B using Protein Homology/analogY Recognition Engine V 2.0 (Phyre2; http://www.sbg.bio.ic.ac.uk/phyre2/html/page.cgi?id=index) [23]; 89 % of the amino acid residues were modeled at >90 % confidence. P.G192R is located in the hypervariable C-terminal domain which is depicted in red
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
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getmorefigures.php?uid=PMC4581468&req=5

Fig1: Identification of the RAB39B p.G192R mutation by whole exome sequencing in a multigenerational kindred with Parkinson’s disease. a Pedigree diagram; individuals affected with Parkinson’s disease are represented with black symbols, unaffected individuals with open symbols. Age at onset is indicated immediately below each symbol, followed by age at last clinical evaluation. Wt = wild type; Mut = mutation (p.G192R). b Multispecies protein sequence alignment. Hs = Homo sapiens; Mm = Mus musculus; Dr = Danio rerio (zebrafish); Dm = Drosophila melanogaster; Ce = Caenorhabditis elegans. c Predicted protein structure of RAB39B using Protein Homology/analogY Recognition Engine V 2.0 (Phyre2; http://www.sbg.bio.ic.ac.uk/phyre2/html/page.cgi?id=index) [23]; 89 % of the amino acid residues were modeled at >90 % confidence. P.G192R is located in the hypervariable C-terminal domain which is depicted in red
Mentions: We studied a U.S. family of European origin in which 7 individuals (5 males and 2 females) were affected and met UK PD Society Brain Bank clinical diagnostic criteria for PD [5] (Fig. 1a). The clinical characteristics of the affected family members are provided in Table 1. None of these individuals displayed atypical findings on neurological examination but two of them (III-15 and IV-4) had mild intellectual disability since childhood. DNA was available for 6 affected and 10 unaffected members of the family. We performed WES on 4 affected (III-4, III-9, III-11, and III-18) and 1 unaffected (III-13) family members. We filtered out all variants with a frequency >1 % in 515 controls from the NHLBI Exome Sequencing Project [6, 7] or that failed to meet the quality thresholds of the Genome Analysis ToolKit (GATK) “Best Practices” [8]. We identified three nonsynonymous variants that passed all filters, segregated with PD among the 5 individuals who underwent WES, and were confirmed by Sanger sequencing: USP1 c.573G > A (p.M191I), MVP c.2594G > T (p.G865V), and RAB39B c.574G > A (p.G192R) (Table 2). We then genotyped these three variants in all remaining family members and found that only RAB39B p.G192R was present in all six affected subjects. Furthermore, RAB39B p.G192R was not observed among 87,725 X chromosomes successfully sequenced for RAB39B in the Exome Aggregation Consortium database (ExAC; http://exac.broadinstitute.org). The amino acid G192 is highly conserved across species (Fig. 1b) and this mutation is predicted to be deleterious as evidenced by a Combined Annotation Dependent Depletion (CADD) [9] score of 29.4.Fig. 1

Bottom Line: We identified a missense mutation (c.574G > A; p.G192R) in the RAB39B gene that closely segregated with disease and exhibited X-linked dominant inheritance with reduced penetrance in females.Experiments in PC12 and SK-N-BE(2)C cells demonstrated that p.G192R resulted in mislocalization of the mutant protein, possibly by altering the structure of the hypervariable C-terminal domain which mediates intracellular targeting.Further characterization of normal and aberrant RAB39B function might elucidate important mechanisms underlying neurodegeneration in PD and related disorders.

View Article: PubMed Central - PubMed

Affiliation: Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA. nachofm@uw.edu.

ABSTRACT

Objective: To identify the causal gene in a multi-incident U.S. kindred with Parkinson's disease (PD).

Methods: We characterized a family with a classical PD phenotype in which 7 individuals (5 males and 2 females) were affected with a mean age at onset of 46.1 years (range, 29-57 years). We performed whole exome sequencing on 4 affected and 1 unaffected family members. Sanger-sequencing was then used to verify and genotype all candidate variants in the remainder of the pedigree. Cultured cells transfected with wild-type or mutant constructs were used to characterize proteins of interest.

Results: We identified a missense mutation (c.574G > A; p.G192R) in the RAB39B gene that closely segregated with disease and exhibited X-linked dominant inheritance with reduced penetrance in females. The mutation occurred in a highly conserved amino acid residue and was not observed among 87,725 X chromosomes in the Exome Aggregation Consortium dataset. Sequencing of the RAB39B coding region in 587 familial PD cases yielded two additional mutations (c.428C > G [p.A143G] and c.624_626delGAG [p.R209del]) that were predicted to be deleterious in silico but occurred in families that were not sufficiently informative to assess segregation with disease. Experiments in PC12 and SK-N-BE(2)C cells demonstrated that p.G192R resulted in mislocalization of the mutant protein, possibly by altering the structure of the hypervariable C-terminal domain which mediates intracellular targeting.

Conclusions: Our findings implicate RAB39B, an essential regulator of vesicular-trafficking, in clinically typical PD. Further characterization of normal and aberrant RAB39B function might elucidate important mechanisms underlying neurodegeneration in PD and related disorders.

No MeSH data available.


Related in: MedlinePlus