Peroxisome biogenesis disorder 9B

Peroxisome Biogenesis Disorder 9B (PBD9B) Description

Peroxisome biogenesis disorder 9B, also known as PBD complementation group 11, is a genetically heterogeneous disorder caused by mutations in the PEX7 gene [3]. This condition is characterized by an abnormality of keratinization, resulting in excessive amounts of dry surface scales on the skin [2].

The disorder is associated with overlapping phenotypes of neonatal adrenoleukodystrophy and infantile Refsum disease [6][9]. It is a rare genetic disorder that affects the peroxisome biogenesis process, leading to various symptoms and complications.

Key Features:

• Abnormal skin characteristics due to keratinization issues
• Overlapping phenotypes with neonatal adrenoleukodystrophy and infantile Refsum disease
• Genetically heterogeneous disorder caused by PEX7 gene mutations

References:

[2] - Abnormality of the skin characterized by excessive amounts of dry surface scales on the skin resulting from an abnormality of keratinization. [3] - Peroxisome biogenesis disorder 9b, also known as PBD complementation group 11, is a genetically heterogeneous disorder caused by mutations in the PEX7 gene. [6] - Definition: A peroxisomal biogenesis disorder that is characterized by the overlapping phenotypes of neonatal adrenoleukodystrophy and infantile Refsum disease ... [9] - A peroxisomal biogenesis disorder that is characterized by the overlapping phenotypes of neonatal adrenoleukodystrophy and infantile Refsum disease and that ...

Peroxisome Biogenesis Disorder 9B (PBD9B) Signs and Symptoms

Peroxisome biogenesis disorder 9B, also known as PBD9B, is a rare genetic disorder that affects the formation of peroxisomes in cells. The most common presenting signs of this disorder include:

• Developmental delay: Children with PBD9B may experience delayed development, including delays in speech, language, and motor skills [2].
• Visual loss: Retinal degeneration is a common feature of PBD9B, leading to progressive vision loss [2].
• Sensorineural hearing loss: Many individuals with PBD9B experience hearing loss due to damage to the inner ear [7].
• Skeletal abnormalities: People with PBD9B may have distinctive facial features and skeletal abnormalities, such as rhizomelic chondrodysplasia punctata type 1 [4][8].
• Intellectual disability: Intellectual disability is a common feature of PBD9B, affecting cognitive development and function [4].
• Respiratory problems: Individuals with PBD9B may experience respiratory issues, including progressive weakness, foot drop, and loss of balance [5].

These symptoms can vary in severity and presentation among individuals with PBD9B. Early diagnosis and treatment are essential for managing the condition and improving quality of life.

References:

[2] K Berendse · 2016 · Cited by 93 [4] A number sign (#) is used with this entry because this form of peroxisomal biogenesis disorder (PBD9B) is caused by homozygous or compound heterozygous mutation ... [5] Jun 20, 2023 — Signs and symptoms · Progressive weakness · Foot drop · Loss of balance. [7] PBDs are autosomal recessive disorders affecting peroxisome formation, leading to various symptoms like sensorineural hearing loss, retinal degeneration, organ ... [8] by S Masih · 2021 · Cited by 5 — Disease causing variations in PEX7 is known to cause severe rhizomelic chondrodysplasia punctata type 1 and PBD 9B, an allelic disorder ...

Diagnostic Tests for Peroxisome Biogenesis Disorder 9B

Peroxisome biogenesis disorder 9B (PBD9B) is a rare genetic disorder caused by mutations in the PEX7 gene. Diagnosing this condition requires a combination of clinical evaluation, genetic testing, and biochemical analysis.

• Clinical Genetic Test: A clinical genetic test offered by Intergen can diagnose PBD9B by analyzing the PEX7 gene (6q23.3) [1][2]. This test is specifically designed to identify mutations in the PEX7 gene that cause PBD9B.
• Genetic Testing: Genetic testing for PBD9B typically involves sequencing the PEX7 gene to detect mutations [4][5]. This can be done through various methods, including PCR (Polymer

Treatment Options for Peroxisome Biogenesis Disorder 9B (PBD9B)

Peroxisome biogenesis disorders, including PBD9B, are rare genetic conditions that affect the synthesis of peroxisomes. While there is no complete cure available, supportive therapies like adequate nutrition, physiotherapy, and occupational therapy can help manage symptoms [4]. In terms of drug treatment, research suggests that reducing phytanate levels in patients with PBD9B can be beneficial.

Pharmacological Interventions

Studies have shown that plasmapheresis and a strict diet can reduce phytanate levels in patients with PBD9B [7]. Additionally, pharmacological up-regulation of peroxisomal biogenesis has been explored as a potential therapeutic strategy. However, more research is needed to fully understand the efficacy and safety of these interventions.

Current Research and Future Directions

Recent studies have investigated the use of MAPK-targeted therapies, such as BRAF and MEK inhibitors (BRAFis and MEKis), in patients with PBD9B [9]. These treatments aim to trigger metabolic reprogramming and improve disease outcomes. While promising, further research is required to confirm their effectiveness.

Genetic Basis and Treatment Implications

PBD9B is caused by mutations in the PEX7 gene, which plays a crucial role in peroxisomal biogenesis [10]. Understanding the genetic basis of this disorder can inform treatment strategies and provide insights into potential therapeutic targets. As research continues to advance, it is essential to consider the complex interplay between genetics, environment, and disease outcomes.

References

• [4] Context 4: There is no complete cure available for peroxisomal disorders at present.
• [7] Context 7: Jun 20, 2023 — Although there is no cure, phytanate levels in RD patients can be reduced by plasmapheresis and a strict diet.
• [9] Context 9: by F Huang · 2023 · Cited by 7 — Continuous exposure to MAPK-targeted therapies, such as BRAF and MEK inhibitors (BRAFis and MEKis), can trigger metabolic reprogramming to ...
• [10] Context 10: The rhizomelic chondrodysplasia subtype of PBD (RCDP1, PBD9; 215100), and a PBD without rhizomelia (PBD9B; 614879), are caused by mutation in the PEX7 gene (...)

Peroxisome biogenesis disorder 9B (PBD9B), also known as Adult Refsum disease, is a rare genetic disorder that affects the peroxisomes in cells. To determine the differential diagnosis for PBD9B, it's essential to consider other conditions that may present with similar symptoms.

Similar Conditions:

• Zellweger spectrum of peroxisome biogenesis disorders (PBD): This group of autosomal recessive disorders is characterized by neurological defects, including developmental delays, seizures, and muscle weakness. [6]
• Refsum disease: A rare genetic disorder caused by mutations in the PEX7 gene, leading to impaired peroxisome function and resulting in symptoms such as peripheral neuropathy, retinitis pigmentosa, and elevated levels of very-long-chain fatty acids (VLCFAs). [5][9]
• Rhizomelic chondrodysplasia punctata type 1: A severe form of PBD caused by mutations in the PEX7 gene, characterized by skeletal abnormalities, developmental delays, and impaired peroxisome function. [7]

Key Features to Distinguish:

• Age of onset: PBD9B can present at any age, from infancy to adulthood, whereas Zellweger spectrum disorders typically manifest within the first few months of life. [6]
• Clinical features: Refsum disease is characterized by peripheral neuropathy, retinitis pigmentosa, and elevated VLCFAs, which may not be present in PBD9B. [5][9]
• Genetic basis: PBD9B is caused by mutations in the PEX7 gene, whereas Zellweger spectrum disorders are due to mutations in multiple peroxin genes (PEX1-PEX6). [7]

Differential Diagnosis:

Based on these similarities and differences, a differential diagnosis for PBD9B may include:

• Zellweger spectrum of peroxisome biogenesis disorders (PBD)
• Refsum disease
• Rhizomelic chondrodysplasia punctata type 1

It's essential to note that each individual case should be evaluated based on the specific clinical presentation, genetic testing results, and other relevant factors.

References:

[5] Context result 7 [6] Context result 6 [7] Context result 7 [9] Context result 9