autosomal recessive spinocerebellar ataxia 6

Autosomal recessive spinocerebellar ataxias (ARCA) are a group of rare genetic disorders that affect the cerebellum and spinal cord, leading to problems with coordination and movement. In the case of ARCA, the condition is inherited in an autosomal recessive pattern, meaning that a person must inherit two copies of the abnormal gene, one from each biological parent, who are generally asymptomatic.

ARCA typically presents early in life, often before the age of 20, with symptoms such as:

• Degeneration or abnormal development of the cerebellum and spinal cord
• Progressive problems with coordination and movement
• Difficulty with balance and walking
• Muscle weakness and wasting
• Nystagmus (involuntary eye movements)
• Other neurological symptoms

It's worth noting that ARCA is a rare condition, and more research is needed to fully understand its causes and effects. However, it's clear that autosomal recessive spinocerebellar ataxias are a serious group of disorders that require prompt medical attention.

References:

• [12] describes ARCA as neurological disorders characterized by degeneration or abnormal development of cerebellum and spinal cord, autosomal recessive inheritance and, in most cases, early onset occurring before the age of 20.
• [10] mentions that there are also autosomal recessive spinocerebellar ataxias, where a person inherits an abnormal gene from both biological parents, who are generally asymptomatic.

Autosomal recessive spinocerebellar ataxia (SCA) is a rare genetic disorder that affects the cerebellum, leading to progressive loss of motor coordination and balance. The signs and symptoms of autosomal recessive SCA can vary depending on the specific subtype, but here are some common features associated with SCA6:

• Poor muscle control: Ataxia describes poor muscle control that causes clumsy movements, affecting walking and balance, hand coordination, speech, and swallowing.
• Gait unsteadiness: The first symptoms of SCA6 can be unsteady gait, stumbling, and imbalance in about 90% of cases.
• Speech difficulties: In some cases, the first symptom is unclear speech (dysarthria) in about 10% of cases.
• Eye movement problems: Nystagmus (involuntary eye movements) and double vision can occur early on.
• Vertigo and diplopia: Episodic vertigo and diplopia (double vision) are also common symptoms.
• Progressive decline: The symptoms slowly worsen over several years, leading to significant disability.

It's essential to note that the age of onset for SCA6 can range from 19 to 73 years, with a mean age of onset between 43 and 52 years. Early recognition and treatment are crucial in managing the disease progression and improving quality of life.

References:

• [3] Other early signs and symptoms of SCA6 include speech difficulties, involuntary eye movements (nystagmus), and double vision.
• [7] In most cases, the first symptoms of SCA6 are unsteady gait, stumbling, and imbalance. In about 10 percent of the cases, the first symptom is unclear speech (dysarthria) ...
• [8] Spinocerebellar ataxia type 6 is a late-onset ataxia syndrome additionally characterized by positional vertigo and downbeating nystagmus.
• [9] Spinocerebellar ataxia type 6 (SCA6) is characterized by adult-onset, slowly progressive cerebellar ataxia, dysarthria, and nystagmus.

Autosomal recessive spinocerebellar ataxia (SCA) 6, also known as SCAR, is a rare genetic disorder that affects the cerebellum and leads to progressive problems with movement. Diagnostic tests for autosomal recessive SCA 6 are crucial in confirming the diagnosis.

DNA Testing DNA testing is highly sensitive and specific and provides a definitive diagnosis for an estimated 50-60% of Caucasian patients with findings of dominant spinocerebellar ataxia, including SCAR (Bird TD, 1998 Oct 28 [Updated 2019 Apr 18]). This test examines the trinucleotide repeat regions exclusively (Tan EK, 2001).

Molecular Genetic Testing Molecular genetic testing can assist in diagnosis when combined with family history, physical examination, and neuroimaging. Approximately 50% of ataxia is caused by mutations in genes that are detectable through DNA testing (Bird TD, 1998 Oct 28 [Updated 2019 Apr 18]). This test can help identify the specific genetic mutation responsible for SCAR.

Other Diagnostic Tests For cerebellar ataxia, magnetic resonance imaging of the brain is the initial diagnostic test of choice (Am J Hum Genet, 2011; 89(2):320–7). Other early signs and symptoms of SCAR include speech difficulties, involuntary eye movements (nystagmus), and double vision (Jul 29, 2022).

References

• Bird TD. Hereditary Ataxia Overview. 1998 Oct 28 [Updated 2019 Apr 18].
• Tan EK. Autosomal dominant spinocerebellar ataxia: a review of the literature. 2001.
• Am J Hum Genet, 2011; 89(2):320–7.

Note: The frequencies of SCAs vary significantly in different populations (Tan EK, 2001).

Based on the available information, it appears that there are no FDA-approved medications specifically for the treatment of autosomal dominant spinocerebellar ataxia 6 (SCA6). However, some potential therapies and treatments may be considered.

• Occupational and physical therapy may be beneficial in managing symptoms and improving quality of life [1].
• Gabapentin has been shown to improve cerebellar signs in cases of cerebellar cortical atrophy, which may be relevant for SCA6 patients [3].
• A clinical trial for the drug riluzole was found to be effective for the symptomatic treatment of several etiologies of autosomal dominant SCA, although its effectiveness for SCA6 specifically is unclear [4].

It's essential to note that genetic counseling should be proposed to individuals having the disease-causing mutation, as SCA6 is inherited autosomal dominantly [5]. Additionally, there are no known effective treatments or cures for spinocerebellar ataxia (SCA) in general, which includes SCA6 [9].

References: [1] SD Ghanekar · 2022 [3] K Nakamura · 2009 [4] DD Bushart · 2016 [5] Context result 5 [9] Context result 9

Autosomal recessive spinocerebellar ataxias are a group of rare genetic disorders that affect the cerebellum and lead to progressive loss of coordination, balance, and speech. The differential diagnosis for autosomal recessive spinocerebellar ataxia 6 (SCA6) involves considering various other conditions that may present with similar symptoms.

Conditions to Consider:

• Spinocerebellar Ataxia Type 3 (SCA3): Also known as Machado-Joseph disease, this is an autosomal dominant disorder characterized by adult-onset ataxia, dysarthria, and early oculomotor disturbances [6].
• Spinocerebellar Ataxia Type 5 (SCA5): This is another autosomal dominant disorder that presents with adult-onset cerebellar gait ataxia, dysmetria, dysarthria, and nystagmus [5].
• Spinocerebellar Ataxia Type 7 (SCA7): This is an autosomal dominant disorder characterized by adult-onset ataxia, dysarthria, and early oculomotor disturbances, similar to SCA3 [11].
• Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS): This is a rare genetic disorder that affects the cerebellum and leads to progressive loss of coordination, balance, and speech. It is characterized by spasticity, ataxia, and dysarthria [12].
• Spinocerebellar Ataxia Autosomal Recessive 8 (SCAR8): This is another rare genetic disorder that affects the cerebellum and leads to progressive loss of coordination, balance, and speech. It is characterized by spasticity, ataxia, and dysarthria [12].

Key Features to Consider:

• Age of Onset: The age of onset for SCA6 ranges from 19 to 73 years, with a mean age of onset between 43 and 52 years [14].
• Initial Symptoms: Initial symptoms are gait unsteadiness, stumbling, and imbalance (in ~90%) and dysarthria (in ~10%) [14].
• Progression: The disease progresses to involve all persons with gait ataxia, upper-limb incoordination, and speech difficulties [14].

Differential Diagnosis:

To diagnose autosomal recessive spinocerebellar ataxia 6 (SCA6), it is essential to consider the above conditions and features. A comprehensive medical history, physical examination, and genetic testing can help differentiate SCA6 from other spinocerebellar ataxias and rare genetic disorders.

References:

[5] Spinocerebellar Ataxia Type 5 (SCA5)

[6] Spinocerebellar Ataxia Type 3 (SCA3)

[11] Spinocerebellar Ataxia Type 7 (SCA7)

[12] Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) and Spinocerebellar Ataxia Autosomal Recessive 8 (SCAR8)

[14] Spinocerebellar Ataxia Type 6 (SCA6)