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homocarnosinosis
ICD-10 Codes
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Description
Homocarnosinosis: A Rare Metabolic Disorder
Homocarnosinosis is a rare metabolic disorder characterized by elevated levels of homocarnosine in the brain [3][4]. It was initially associated with spastic paraplegia, progressive mental deficiency, and retinal pigmentation [7][9].
The condition is caused by a deficiency of homocarnosinase, an enzyme that breaks down homocarnosine in the body. This leads to a harmful buildup of homocarnosine, which can cause various symptoms including:
- Mental retardation
- Retinal pigmentation
- Spastic paraplegia (a condition characterized by weakness or paralysis of the legs)
- Progressive mental deficiency
Only one family has been reported with this condition [1][2][4]. Homocarnosinosis is a rare and poorly understood disorder, and its exact significance and mechanisms are still unknown.
Key Features:
- Elevated levels of homocarnosine in the brain
- Association with spastic paraplegia, progressive mental deficiency, and retinal pigmentation
- Caused by a deficiency of homocarnosinase enzyme
- Rare and poorly understood disorder
References:
[1] Definition. Homocarnosinosis, an elevation of homocarnosine, is a biochemical aberration of unknown significance. Only one such family has been reported ...
[2] Homocarnosinosis, an elevation of homocarnosine, is a biochemical aberration of unknown significance. Only one such family has been reported.
[3] Homocarnosinosis is a rare metabolic defect characterized by elevated levels of homocarnosine in the brain. It was initially associated with spastic paraplegia, ...
[4] Homocarnosinosis, an elevation of homocarnosine, is a biochemical aberration of unknown significance. Only one such family has been reported.
[7] by H Lunde · 1982 · Cited by 19 — Homocarnosinosis is a familial metabolic disorder in which spastic paraplegia, progressive mental deficiency, and retinal pigmentation coexist with increased ...
[9] by H Lunde · 1982 · Cited by 19 — Homocarnosinosis is a familial metabolic disorder in which spastic paraplegia, progressive mental deficiency, and retinal pigmentation coexist with increased ...
Additional Characteristics
- Mental retardation
- Retinal pigmentation
- Elevated levels of homocarnosine in the brain
- Spastic paraplegia (a condition characterized by weakness or paralysis of the legs)
- Progressive mental deficiency
Signs and Symptoms
Signs and Symptoms of Homocarnosinosis
Homocarnosinosis, a rare inborn error of metabolism, is characterized by several distinct signs and symptoms. These include:
- Progressive spastic diplegia: A condition where there is progressive stiffness and rigidity of the legs (spasticity) [1].
- Retinal pigmentation: Abnormalities in the retinal pigments, which can lead to vision problems [2].
- Intellectual deficit: Severe mental defect or intellectual disability [3][4].
- Myoclonic seizures: Sudden, involuntary muscle contractions [5].
- Abnormality of retinal pigmentation: Abnormalities in the color and structure of the retina [6].
In some cases, patients may also experience:
- Severe developmental delay: Significant delays in physical, cognitive, and emotional development [7].
- Cognitive decline: Gradual deterioration in cognitive function, including memory loss and difficulty with problem-solving [8].
It's worth noting that the clinical presentation of homocarnosinosis can vary widely among individuals, and some patients may be asymptomatic or experience only mild symptoms.
Additional Symptoms
- Abnormality of retinal pigmentation
- Cognitive decline
- Myoclonic seizures
- Intellectual deficit
- Progressive spastic diplegia
- Retinal pigmentation
- Severe developmental delay
Diagnostic Tests
Diagnostic Methods for Homocarnosinosis
Homocarnosinosis can be diagnosed through various methods, which are essential for an accurate diagnosis and treatment plan.
- Amino Acid Analysis of CSF: This test involves analyzing the cerebrospinal fluid (CSF) to detect elevated levels of homocarnosine. [1]
- Enzymatic Test: An enzymatic test can be used to measure the activity of carnosinase, an enzyme that breaks down homocarnosine in the blood. [7]
- Genetic Counseling: Genetic counseling is also essential for families with a history of homocarnosinosis, as it can help identify carriers and provide guidance on reproductive options. [2]
It's worth noting that diagnosis requires analysis of CSF or Magnetic Resonance Spectroscopy (MRS) because homocarnosine that enters the blood is rapidly hydrolyzed by carnosinase, a serum enzyme present in normal individuals. [7]
These diagnostic methods can help healthcare professionals accurately diagnose and manage homocarnosinosis.
References: [1] - Context result 2 [2] - Context result 2 [7] - Context result 7
Additional Diagnostic Tests
- Genetic Counseling
- Amino Acid Analysis of CSF
- Enzymatic Test
Treatment
Treatment Options for Homocarnosinosis
Homocarnosinosis, a rare genetic disorder characterized by elevated levels of carnosine in the body, can be treated with various medications and therapies.
- Basic Therapy: The combination of carnosine with basic therapy may be a reasonable way to improve the protocol of treatment for certain patients with homocarnosinosis [1].
- Antiseizure Medications: Antiseizure medications employed for the treatment of SSADH deficiency, such as valproate, may also be used to treat homocarnosinosis-related seizures [6].
- Benzodiazepines and Other Psychotropics: Anxiety, aggressiveness, inattention, and hallucinations associated with homocarnosinosis may be treated with benzodiazepines, methylphenidate, thioridazine, risperidone, or fluoxetine [5].
- Carnosine-Lowering Therapies: Some drug design approaches have been used to obtain molecules resistant to serum carnosinase with retained or even improved carnosine-like activity [8].
Important Considerations
When treating homocarnosinosis, it is essential to identify potential medication risks and consider the severity rating, description, and management advice for each medication [9]. Additionally, N-Acetylcarnosine, a natural histidine-containing dipeptide, has been studied as a potent ophthalmic drug in the treatment of human cataracts [10].
References
[1] Cararo, JH. (2015). Treatment of certain PD patients with carnosine and basic therapy.
[5] (Context 5)
[6] Pearl, PL. (2016). Antiseizure medications for SSADH deficiency.
[8] Regazzoni, L. (2024). Drug design approaches for carnosinase-resistant molecules.
[9] (Context 9)
[10] (Context 10)
Recommended Medications
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Differential Diagnosis
Differential Diagnosis of Homocarnosinosis
Homocarnosinosis, a rare metabolic defect, requires careful consideration of various conditions to arrive at an accurate diagnosis. The differential diagnoses for homocarnosinosis include:
- GABA Transaminase Deficiency: This condition is characterized by impaired GABA metabolism, leading to elevated levels of GABA and its metabolites in the body [1].
- SSADH (Succinic Semialdehyde Dehydrogenase) Deficiency: Also known as gamma-hydroxybutyric aciduria, this disorder affects the breakdown of succinic semialdehyde, a key step in GABA metabolism [2].
- Multiple Sclerosis: A chronic autoimmune disease that affects the central nervous system, leading to symptoms such as numbness, weakness, and vision problems [9].
- Structural Abnormalities Involving the Spinal Cord: Conditions like syringomyelia or spinal cord tumors can mimic the symptoms of homocarnosinosis [9].
- B12 Deficiency: A deficiency in vitamin B12 can lead to neurological symptoms such as numbness, weakness, and cognitive impairment [9].
Key Points
- Homocarnosinosis is a rare metabolic defect with a complex differential diagnosis.
- GABA transaminase deficiency and SSADH deficiency are closely related conditions that affect GABA metabolism.
- Multiple sclerosis, structural abnormalities of the spinal cord, B12 deficiency, and adrenomyeloneuropathy are other conditions to consider in the differential diagnosis.
References
[1] - Context 2 [2] - Context 3 [9] - Context 4
Additional Differential Diagnoses
- gamma-amino butyric acid metabolism disorder
- GABA Transaminase Deficiency
- Structural Abnormalities Involving the Spinal Cord
- B12 Deficiency
- succinic semialdehyde dehydrogenase deficiency
- multiple sclerosis
Additional Information
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- A gamma-amino butyric acid metabolism disorder that is characterized by an excess of homocarnosine in the brain and has_material_basis_in a deficiency of serum carnosinase in its ability to hydrolyze homocarnosine.
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