Inherited ataxia

SAMD9 and SAMD9L are two interferon-regulated genes located adjacent to each other on chromosome 7q21.2. Germline gain-of-function mutations in SAMD9/SAMD9L are the genetic cause of MIRAGE syndrome, ataxia pancytopenia syndrome (ATXPC), myeloid leukemia syndrome with monosomy 7 (MLSM7), refractory cytopenia of childhood (RCC), transient monosomy 7 in children, SAMD9L-associated autoinflammatory disease (SAAD) and a proportion of inherited aplastic anemia and bone marrow failure syndromes.

Expanded CAG repeats in coding regions of different genes are the most common cause of dominantly inherited spinocerebellar ataxias (SCAs). These repeats are unstable through the germline, and larger repeats lead to earlier onset. We measured somatic expansion in blood samples collected from 30 SCA1, 50 SCA2, 74 SCA3, and 30 SCA7 individuals over a mean interval of 8.5 years, along with postmortem tissues and fetal tissues from SCA1, SCA3, and SCA7 individuals to examine somatic expansion at different stages of life...

OBJECTIVE: Essential Tremor (ET) is one of the most common neurological disorders. In most instances ET is inherited as an autosomal dominant trait with age-related penetrance (virtually complete in advanced age); however, ET genetics remains elusive. The current study aims to identify possibly pathogenic genetic variants in a group of well-characterized ET families. METHODS: 34 individuals from 14 families with dominant ET were clinically evaluated and studied by whole exome sequencing studies (after excluding trinucleotide expansion disorders)...

The reduced penetrance of TBP intermediate alleles and the recently proposed possible digenic TBP/STUB1 inheritance raised questions on the possible mechanism involved opening a debate on the existence of SCA48 as a monogenic disorder. We here report clinical and genetic results of two apparently unrelated patients carrying the same STUB1 variant(c.244G > T;p.Asp82Tyr) with normal TBP alleles and a clinical picture fully resembling SCA48, including cerebellar ataxia, dysarthria and mild cognitive impairment...

The spinocerebellar ataxias (SCA) comprise a group of inherited neurodegenerative diseases. Machado-Joseph Disease (MJD) or spinocerebellar ataxia 3 (SCA3) is the most common autosomal dominant form, caused by the expansion of CAG repeats within the ataxin-3 (ATXN3) gene. This mutation results in the expression of an abnormal protein containing long polyglutamine (polyQ) stretches that confers a toxic gain of function and leads to misfolding and aggregation of ATXN3 in neurons. As a result of the neurodegenerative process, SCA3 patients are severely disabled and die prematurely...

INTRODUCTION: Ataxia is one of the clinical findings of the movement disorder disease group. Although there are many underlying etiological reasons, genetic etiology has an increasing significance thanks to the recently developing technology. The aim of this study is to present the variants detected in WES analysis excluding non-genetic causes, in patients with ataxia. METHODS: Thirty-six patients who were referred to us with findings of ataxia and diagnosed through WES or other molecular genetic analysis methods were included in our study...

Alexander disease (AxD) is a rare inherited autosomal dominant (AD) disease with different clinical phenotypes according to the age of onset. It is caused by mutations in the glial fibrillary acid protein (GFAP) gene, which causes GFAP accumulation in astrocytes. A wide spectrum of mutations has been described. For some variants, genotype-phenotype correlations have been described, although variable expressivity has also been reported in late-onset cases among members of the same family. We present the case of a 19-year-old girl who developed gait ataxia and subtle involuntary movements, preceded by a history of enuresis and severe scoliosis...

BACKGROUND: To investigate the genetics of early-onset progressive cerebellar ataxia in Iran, we conducted a study at the Children's Medical Center (CMC), the primary referral center for pediatric disorders in the country, over a three-year period from 2019 to 2022. In this report, we provide the initial findings from the national registry. METHODS: We selected all early-onset patients with an autosomal recessive mode of inheritance to assess their phenotype, paraclinical tests, and genotypes...

Vacuolar protein sorting 13 homolog D (VPS13D) gene encodes a protein involved in trafficking of membrane proteins between the trans-Golgi network and the prevacuolar compartment. This study reports a novel homozygous mutation (c.12494T>C p.Ile4165Thr) in the VPS13D gene in a Saudi female diagnosed with autosomal recessive spinocerebellar ataxia type 4 (SCAR4). The patient's clinical presentation, including progressive weakness, ataxia, and numbness, aligns with SCAR4 characteristics. The comprehensive evaluation, comprising neurological examination, brain MRI, and genetic testing, revealed distinctive features consistent with autosomal recessive inheritance...

Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability (ID) and single gene cause of autism. Although most patients with FXS and the full mutation (FM) have complete methylation of the fragile X messenger ribonucleoprotein 1 ( FMR1 ) gene, some have mosaicism in methylation and/or CGG repeat size, and few have completely unmethylated FM alleles. Those with a complete lack of methylation are rare, with little literature about the cognitive and behavioral phenotypes of these individuals...

Hereditary spastic paraplegia type 5 (SPG5) is an autosomal recessively inherited movement disorder characterized by progressive spastic gait disturbance and afferent ataxia. SPG5 is caused by bi-allelic loss of function mutations in CYP7B1 resulting in accumulation of the oxysterols 25-hydroxycholesterol and 27-hydroxycholesterol in serum and cerebrospinal fluid of SPG5 patients. An effect of 27- hydroxycholesterol via the estrogen and liver X receptors was previously shown on bone homeostasis. This study analyzed bone homeostasis and osteopenia in 14 SPG5 patients as a non-motor feature leading to a potential increased risk for bone fractures...

BACKGROUND AND OBJECTIVES: Creatine transporter deficiency (CTD) is a rare X-linked genetic disorder characterized by intellectual disability (ID). We evaluated the clinical characteristics and trajectory of patients with CTD and the impact of the disease on caregivers to identify relevant endpoints for future therapeutic trials. METHODS: As part of a French National Research Program, patients with CTD were included based on (1) a pathogenic SLC6A8 variant and (2) ID and/or autism spectrum disorder...

BACKGROUND AND AIMS: Water-soluble vitamins play an essential coenzyme role in the nervous system. Acquired vitamin deficiencies are easily treatable, however, without treatment, they can lead to irreversible complications. This study aimed to provide clinical, laboratory parameters and neuroimaging data on vitamin deficiencies in an attempt to facilitate early diagnosis and prompt supplementation. METHODS: From July 1998 to July 2023, patients at Necker-Enfants-Malades Hospital presenting with acute neurological symptoms attributed to acquired vitamin deficiency were included...

Joubert syndrome (JS) is a recessively inherited congenital ataxia characterized by hypotonia, psychomotor delay, abnormal ocular movements, intellectual disability, and a peculiar cerebellar and brainstem malformation, the "molar tooth sign." Over 40 causative genes have been reported, all encoding for proteins implicated in the structure or functioning of the primary cilium, a subcellular organelle widely present in embryonic and adult tissues. In this paper, we developed an in vitro neuronal differentiation model using patient-derived induced pluripotent stem cells (iPSCs), to evaluate possible neurodevelopmental defects in JS...

The objective of the study is to evaluate the evolving phenotype and genetic spectrum of patients with succinic semialdehyde dehydrogenase deficiency (SSADHD) in long-term follow-up. Longitudinal clinical and biochemical data of 22 pediatric and 9 adult individuals with SSADHD from the patient registry of the International Working Group on Neurotransmitter related Disorders (iNTD) were studied with in silico analyses, pathogenicity scores and molecular modeling of ALDH5A1 variants. Leading initial symptoms, with onset in infancy, were developmental delay and hypotonia...

Pathogenic variants in six aminoacyl-tRNA synthetase (ARS) genes are implicated in neurological disorders, most notably inherited peripheral neuropathies. ARSs are enzymes that charge tRNA molecules with cognate amino acids. Pathogenic variants in asparaginyl-tRNA synthetase ( NARS1 ) cause a neurological phenotype combining developmental delay, ataxia and demyelinating peripheral neuropathy. NARS1 has not yet been linked to axonal Charcot-Marie-Tooth disease. Exome sequencing of patients with inherited peripheral neuropathies revealed three previously unreported heterozygous NARS1 variants in three families...

Friedreich's ataxia (FRDA), the most common recessive inherited ataxia, results from homozygous guanine-adenine-adenine (GAA) repeat expansions in intron 1 of the FXN gene, which leads to the deficiency of frataxin, a mitochondrial protein essential for iron-sulphur cluster synthesis. The study of frataxin protein regulation might yield new approaches for FRDA treatment. Here, we report tumorous imaginal disc 1 (TID1), a mitochondrial J-protein cochaperone, as a binding partner of frataxin that negatively controls frataxin protein levels...

BACKGROUND: Spinocerebellar ataxia 17 (SCA17) is a rare autosomal dominant form of inherited ataxia, caused by heterozygous trinucleotide repeat expansions encoding glutamine in the TATA box-binding protein (TBP) gene. CASE DESCRIPTION: We describe the clinical history, neuropsychological, and neuroimaging findings of a 42-year-old patient who presented for medical attention showing prevalent behavioral and cognitive problems along with progressively worsening gait disturbances...

BACKGROUND: Little is known about the impact of the cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) on cognition. OBJECTIVE: Our objective was to determine the frequency and severity of cognitive impairment in RFC1-positive patients and describe the pattern of deficits. METHODS: Participants underwent a comprehensive neuropsychological assessment. Volume of the cerebellum and its lobules was measured in those who underwent a 3 Tesla-magnetic resonance scan...

BACKGROUND: Preimplantation genetic testing for monogenic disorders (PGT-M) is now widely used as an effective strategy to prevent various monogenic or chromosomal diseases. MATERIAL AND METHODS: In this retrospective study, couples with a family history of hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes and/or carrying the pathogenic genes underwent PGT-M to prevent children from inheriting disease-causing gene mutations from their parents and developing known genetic diseases...