SSADH deficiency possibly associated with enzyme activity-reducing SNPs

Tomoyuki Akiyama, Hitoshi Osaka, Hiroko Shimbo, Tomiko Kuhara, Takashi Shibata, Katsuhiro Kobayashi, Kenji Kurosawa, Harumi Yoshinaga

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Background: Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare autosomal recessive disorder that affects the degradation of gamma-aminobutyric acid and leads to the accumulation of gamma-hydroxybutyric acid (GHB) in body fluids. Diagnosis of SSADH deficiency is challenging, since the neurological symptoms are non-specific. Case: The patient is a nine-year-old Japanese boy who presented with developmental delay, autism, epilepsy, and episodic gait disturbance. Brain magnetic resonance imaging showed hyperintense lesions in the bilateral thalami, globus pallidi, substantia nigra, and dentate nuclei. Urine metabolome analysis revealed elevated GHB, which led to a biochemical diagnosis of SSADH deficiency. Genetic analysis of the ALDH5A1 gene revealed a novel missense mutation c.1586G>A inherited from his father. It also demonstrated three single nucleotide polymorphisms (SNPs) (c.106G>C, c.538C>T, and c.545C>T), all of which were inherited from his mother and are known to reduce SSADH enzyme activity. There were no duplications or deletions in other exons in the patient or his parents. No variants in the upstream, intronic, or downstream regions of the ALDH5A1 gene were found in the patient. Enzymatic assay revealed a marked reduction of SSADH enzyme activity (≈2% of the lower limit of the normal range). Conclusion: Although other mechanisms cannot be fully excluded, the clinical manifestation of SSADH deficiency in this patient may be attributed to the combined effect of the mutation and the three enzyme activity-reducing SNPs. Urine metabolome analysis effectively detected his elevated GHB and is thus considered to be a good screening method for this underdiagnosed and potentially manageable metabolic disorder.

Original languageEnglish
JournalBrain and Development
DOIs
Publication statusAccepted/In press - 2016

Fingerprint

Single Nucleotide Polymorphism
Succinate-Semialdehyde Dehydrogenase
Metabolome
Enzymes
Urine
Cerebellar Nuclei
Globus Pallidus
Enzyme Assays
Body Fluids
Substantia Nigra
Missense Mutation
Autistic Disorder
Thalamus
Gait
Fathers
gamma-Aminobutyric Acid
Genes
Exons
Epilepsy
Reference Values

Keywords

  • ALDH5A1 gene
  • Gamma-aminobutyric acid
  • Gamma-hydroxybutyric acid
  • Metabolome analysis

ASJC Scopus subject areas

  • Clinical Neurology
  • Developmental Neuroscience
  • Pediatrics, Perinatology, and Child Health

Cite this

SSADH deficiency possibly associated with enzyme activity-reducing SNPs. / Akiyama, Tomoyuki; Osaka, Hitoshi; Shimbo, Hiroko; Kuhara, Tomiko; Shibata, Takashi; Kobayashi, Katsuhiro; Kurosawa, Kenji; Yoshinaga, Harumi.

In: Brain and Development, 2016.

Research output: Contribution to journalArticle

Akiyama, Tomoyuki ; Osaka, Hitoshi ; Shimbo, Hiroko ; Kuhara, Tomiko ; Shibata, Takashi ; Kobayashi, Katsuhiro ; Kurosawa, Kenji ; Yoshinaga, Harumi. / SSADH deficiency possibly associated with enzyme activity-reducing SNPs. In: Brain and Development. 2016.
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abstract = "Background: Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare autosomal recessive disorder that affects the degradation of gamma-aminobutyric acid and leads to the accumulation of gamma-hydroxybutyric acid (GHB) in body fluids. Diagnosis of SSADH deficiency is challenging, since the neurological symptoms are non-specific. Case: The patient is a nine-year-old Japanese boy who presented with developmental delay, autism, epilepsy, and episodic gait disturbance. Brain magnetic resonance imaging showed hyperintense lesions in the bilateral thalami, globus pallidi, substantia nigra, and dentate nuclei. Urine metabolome analysis revealed elevated GHB, which led to a biochemical diagnosis of SSADH deficiency. Genetic analysis of the ALDH5A1 gene revealed a novel missense mutation c.1586G>A inherited from his father. It also demonstrated three single nucleotide polymorphisms (SNPs) (c.106G>C, c.538C>T, and c.545C>T), all of which were inherited from his mother and are known to reduce SSADH enzyme activity. There were no duplications or deletions in other exons in the patient or his parents. No variants in the upstream, intronic, or downstream regions of the ALDH5A1 gene were found in the patient. Enzymatic assay revealed a marked reduction of SSADH enzyme activity (≈2{\%} of the lower limit of the normal range). Conclusion: Although other mechanisms cannot be fully excluded, the clinical manifestation of SSADH deficiency in this patient may be attributed to the combined effect of the mutation and the three enzyme activity-reducing SNPs. Urine metabolome analysis effectively detected his elevated GHB and is thus considered to be a good screening method for this underdiagnosed and potentially manageable metabolic disorder.",
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T1 - SSADH deficiency possibly associated with enzyme activity-reducing SNPs

AU - Akiyama, Tomoyuki

AU - Osaka, Hitoshi

AU - Shimbo, Hiroko

AU - Kuhara, Tomiko

AU - Shibata, Takashi

AU - Kobayashi, Katsuhiro

AU - Kurosawa, Kenji

AU - Yoshinaga, Harumi

PY - 2016

Y1 - 2016

N2 - Background: Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare autosomal recessive disorder that affects the degradation of gamma-aminobutyric acid and leads to the accumulation of gamma-hydroxybutyric acid (GHB) in body fluids. Diagnosis of SSADH deficiency is challenging, since the neurological symptoms are non-specific. Case: The patient is a nine-year-old Japanese boy who presented with developmental delay, autism, epilepsy, and episodic gait disturbance. Brain magnetic resonance imaging showed hyperintense lesions in the bilateral thalami, globus pallidi, substantia nigra, and dentate nuclei. Urine metabolome analysis revealed elevated GHB, which led to a biochemical diagnosis of SSADH deficiency. Genetic analysis of the ALDH5A1 gene revealed a novel missense mutation c.1586G>A inherited from his father. It also demonstrated three single nucleotide polymorphisms (SNPs) (c.106G>C, c.538C>T, and c.545C>T), all of which were inherited from his mother and are known to reduce SSADH enzyme activity. There were no duplications or deletions in other exons in the patient or his parents. No variants in the upstream, intronic, or downstream regions of the ALDH5A1 gene were found in the patient. Enzymatic assay revealed a marked reduction of SSADH enzyme activity (≈2% of the lower limit of the normal range). Conclusion: Although other mechanisms cannot be fully excluded, the clinical manifestation of SSADH deficiency in this patient may be attributed to the combined effect of the mutation and the three enzyme activity-reducing SNPs. Urine metabolome analysis effectively detected his elevated GHB and is thus considered to be a good screening method for this underdiagnosed and potentially manageable metabolic disorder.

AB - Background: Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare autosomal recessive disorder that affects the degradation of gamma-aminobutyric acid and leads to the accumulation of gamma-hydroxybutyric acid (GHB) in body fluids. Diagnosis of SSADH deficiency is challenging, since the neurological symptoms are non-specific. Case: The patient is a nine-year-old Japanese boy who presented with developmental delay, autism, epilepsy, and episodic gait disturbance. Brain magnetic resonance imaging showed hyperintense lesions in the bilateral thalami, globus pallidi, substantia nigra, and dentate nuclei. Urine metabolome analysis revealed elevated GHB, which led to a biochemical diagnosis of SSADH deficiency. Genetic analysis of the ALDH5A1 gene revealed a novel missense mutation c.1586G>A inherited from his father. It also demonstrated three single nucleotide polymorphisms (SNPs) (c.106G>C, c.538C>T, and c.545C>T), all of which were inherited from his mother and are known to reduce SSADH enzyme activity. There were no duplications or deletions in other exons in the patient or his parents. No variants in the upstream, intronic, or downstream regions of the ALDH5A1 gene were found in the patient. Enzymatic assay revealed a marked reduction of SSADH enzyme activity (≈2% of the lower limit of the normal range). Conclusion: Although other mechanisms cannot be fully excluded, the clinical manifestation of SSADH deficiency in this patient may be attributed to the combined effect of the mutation and the three enzyme activity-reducing SNPs. Urine metabolome analysis effectively detected his elevated GHB and is thus considered to be a good screening method for this underdiagnosed and potentially manageable metabolic disorder.

KW - ALDH5A1 gene

KW - Gamma-aminobutyric acid

KW - Gamma-hydroxybutyric acid

KW - Metabolome analysis

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