A Novel Homozygous Variant in the Fork-Head-Associated Domain of Polynucleotide Kinase Phosphatase in a Patient Affected by Late-Onset Ataxia With Oculomotor Apraxia Type 4

Rosa Campopiano, Rosangela Ferese, Fabio Buttari, Cinzia Femiano, Diego Centonze, Francesco Fornai, Francesca Biagioni, Maria Antonietta Chiaravalloti, Mauro Magnani, Emiliano Giardina, Anna Ruzzo, Stefano Gambardella

Research output: Contribution to journalArticle

Abstract

Ataxia with oculomotor apraxia (AOA) is a clinical syndrome featuring a group of genetic diseases including at least four separate autosomal-recessive cerebellar ataxias. All these disorders are due to altered genes involved in DNA repair. AOA type 4 (AOA4) is caused by mutations in DNA repair factor polynucleotide kinase phosphatase (PNKP), which encodes for a DNA processing enzyme also involved in other syndromes featured by microcephaly or neurodegeneration. To date, only a few AOA4 patients have been reported worldwide. All these patients are homozygous or compound heterozygous carriers for mutations in the kinase domain of PNKP. In this report, we describe a 56 years old patient affected by AOA4 characterized by ataxia, polyneuropathy, oculomotor apraxia, and cognitive impairment with the absence of dystonia. The disease is characterized by a very late onset (50 years) when compared with other AOA4 patients described so far (median age of onset at 4 years). In this proband, Clinical Exome Analysis through Next Generation Sequencing (NGS) consisting of 4,800 genes, identified the PNKP homozygous mutation p.Gln50Glu. This variant, classified as a likely pathogenic variant according to American College of Medical Genetics (ACMG) guidelines, does not involve the kinase domain but falls in the fork-head-associated (FHA) domain. So far, mutations in such a domain were reported to associate only with a pure seizure syndrome without the classic AOA4 features. Therefore, this is the first report of patients carrying a mutation of the FHA domain within the PNKP gene which expresses the clinical phenotype known as the AOA4 syndrome and the lack of any seizure activity. Further studies are required to investigate specifically the significance of various mutations within the FHA domain, and it would be worth to correlate these variants with the age of onset of the AOA4 syndrome.

Original languageEnglish
Article number1331
JournalFrontiers in Neurology
Volume10
DOIs
Publication statusPublished - Jan 15 2020

Fingerprint

Polynucleotide 5'-Hydroxyl-Kinase
Phosphoric Monoester Hydrolases
Head
Mutation
Age of Onset
DNA Repair
Seizures
Phosphotransferases
Genes
Exome
Apraxias
Microcephaly
Cerebellar Ataxia
Inborn Genetic Diseases
Dystonia
Polyneuropathies
Ataxia
Autosomal recessive 1 Spinocerebellar ataxia
Guidelines
Phenotype

Keywords

  • ataxia with oculomotor apraxia
  • clinical exome
  • late onset
  • neurogenetics
  • PNKP gene

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

Cite this

@article{12c379d3da7140e0b321d96d5971f9bd,
title = "A Novel Homozygous Variant in the Fork-Head-Associated Domain of Polynucleotide Kinase Phosphatase in a Patient Affected by Late-Onset Ataxia With Oculomotor Apraxia Type 4",
abstract = "Ataxia with oculomotor apraxia (AOA) is a clinical syndrome featuring a group of genetic diseases including at least four separate autosomal-recessive cerebellar ataxias. All these disorders are due to altered genes involved in DNA repair. AOA type 4 (AOA4) is caused by mutations in DNA repair factor polynucleotide kinase phosphatase (PNKP), which encodes for a DNA processing enzyme also involved in other syndromes featured by microcephaly or neurodegeneration. To date, only a few AOA4 patients have been reported worldwide. All these patients are homozygous or compound heterozygous carriers for mutations in the kinase domain of PNKP. In this report, we describe a 56 years old patient affected by AOA4 characterized by ataxia, polyneuropathy, oculomotor apraxia, and cognitive impairment with the absence of dystonia. The disease is characterized by a very late onset (50 years) when compared with other AOA4 patients described so far (median age of onset at 4 years). In this proband, Clinical Exome Analysis through Next Generation Sequencing (NGS) consisting of 4,800 genes, identified the PNKP homozygous mutation p.Gln50Glu. This variant, classified as a likely pathogenic variant according to American College of Medical Genetics (ACMG) guidelines, does not involve the kinase domain but falls in the fork-head-associated (FHA) domain. So far, mutations in such a domain were reported to associate only with a pure seizure syndrome without the classic AOA4 features. Therefore, this is the first report of patients carrying a mutation of the FHA domain within the PNKP gene which expresses the clinical phenotype known as the AOA4 syndrome and the lack of any seizure activity. Further studies are required to investigate specifically the significance of various mutations within the FHA domain, and it would be worth to correlate these variants with the age of onset of the AOA4 syndrome.",
keywords = "ataxia with oculomotor apraxia, clinical exome, late onset, neurogenetics, PNKP gene",
author = "Rosa Campopiano and Rosangela Ferese and Fabio Buttari and Cinzia Femiano and Diego Centonze and Francesco Fornai and Francesca Biagioni and Chiaravalloti, {Maria Antonietta} and Mauro Magnani and Emiliano Giardina and Anna Ruzzo and Stefano Gambardella",
year = "2020",
month = "1",
day = "15",
doi = "10.3389/fneur.2019.01331",
language = "English",
volume = "10",
journal = "Frontiers in Neurology",
issn = "1664-2295",
publisher = "Frontiers Research Foundation",

}

TY - JOUR

T1 - A Novel Homozygous Variant in the Fork-Head-Associated Domain of Polynucleotide Kinase Phosphatase in a Patient Affected by Late-Onset Ataxia With Oculomotor Apraxia Type 4

AU - Campopiano, Rosa

AU - Ferese, Rosangela

AU - Buttari, Fabio

AU - Femiano, Cinzia

AU - Centonze, Diego

AU - Fornai, Francesco

AU - Biagioni, Francesca

AU - Chiaravalloti, Maria Antonietta

AU - Magnani, Mauro

AU - Giardina, Emiliano

AU - Ruzzo, Anna

AU - Gambardella, Stefano

PY - 2020/1/15

Y1 - 2020/1/15

N2 - Ataxia with oculomotor apraxia (AOA) is a clinical syndrome featuring a group of genetic diseases including at least four separate autosomal-recessive cerebellar ataxias. All these disorders are due to altered genes involved in DNA repair. AOA type 4 (AOA4) is caused by mutations in DNA repair factor polynucleotide kinase phosphatase (PNKP), which encodes for a DNA processing enzyme also involved in other syndromes featured by microcephaly or neurodegeneration. To date, only a few AOA4 patients have been reported worldwide. All these patients are homozygous or compound heterozygous carriers for mutations in the kinase domain of PNKP. In this report, we describe a 56 years old patient affected by AOA4 characterized by ataxia, polyneuropathy, oculomotor apraxia, and cognitive impairment with the absence of dystonia. The disease is characterized by a very late onset (50 years) when compared with other AOA4 patients described so far (median age of onset at 4 years). In this proband, Clinical Exome Analysis through Next Generation Sequencing (NGS) consisting of 4,800 genes, identified the PNKP homozygous mutation p.Gln50Glu. This variant, classified as a likely pathogenic variant according to American College of Medical Genetics (ACMG) guidelines, does not involve the kinase domain but falls in the fork-head-associated (FHA) domain. So far, mutations in such a domain were reported to associate only with a pure seizure syndrome without the classic AOA4 features. Therefore, this is the first report of patients carrying a mutation of the FHA domain within the PNKP gene which expresses the clinical phenotype known as the AOA4 syndrome and the lack of any seizure activity. Further studies are required to investigate specifically the significance of various mutations within the FHA domain, and it would be worth to correlate these variants with the age of onset of the AOA4 syndrome.

AB - Ataxia with oculomotor apraxia (AOA) is a clinical syndrome featuring a group of genetic diseases including at least four separate autosomal-recessive cerebellar ataxias. All these disorders are due to altered genes involved in DNA repair. AOA type 4 (AOA4) is caused by mutations in DNA repair factor polynucleotide kinase phosphatase (PNKP), which encodes for a DNA processing enzyme also involved in other syndromes featured by microcephaly or neurodegeneration. To date, only a few AOA4 patients have been reported worldwide. All these patients are homozygous or compound heterozygous carriers for mutations in the kinase domain of PNKP. In this report, we describe a 56 years old patient affected by AOA4 characterized by ataxia, polyneuropathy, oculomotor apraxia, and cognitive impairment with the absence of dystonia. The disease is characterized by a very late onset (50 years) when compared with other AOA4 patients described so far (median age of onset at 4 years). In this proband, Clinical Exome Analysis through Next Generation Sequencing (NGS) consisting of 4,800 genes, identified the PNKP homozygous mutation p.Gln50Glu. This variant, classified as a likely pathogenic variant according to American College of Medical Genetics (ACMG) guidelines, does not involve the kinase domain but falls in the fork-head-associated (FHA) domain. So far, mutations in such a domain were reported to associate only with a pure seizure syndrome without the classic AOA4 features. Therefore, this is the first report of patients carrying a mutation of the FHA domain within the PNKP gene which expresses the clinical phenotype known as the AOA4 syndrome and the lack of any seizure activity. Further studies are required to investigate specifically the significance of various mutations within the FHA domain, and it would be worth to correlate these variants with the age of onset of the AOA4 syndrome.

KW - ataxia with oculomotor apraxia

KW - clinical exome

KW - late onset

KW - neurogenetics

KW - PNKP gene

UR - http://www.scopus.com/inward/record.url?scp=85078786794&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85078786794&partnerID=8YFLogxK

U2 - 10.3389/fneur.2019.01331

DO - 10.3389/fneur.2019.01331

M3 - Article

AN - SCOPUS:85078786794

VL - 10

JO - Frontiers in Neurology

JF - Frontiers in Neurology

SN - 1664-2295

M1 - 1331

ER -