SPG5 and multiple sclerosis: clinical and genetic overlap?

Area of Science:

• Neurogenetics
• Metabolic disorders
• Autoimmune diseases

Background:

• Autosomal recessive spastic paraplegia type 5 (AR SPG5) is caused by mutations in the CYP7B1 gene, affecting oxysterol metabolism.
• Oxysterols are crucial for motor neuron survival and immune function.
• SPG5 shares clinical and MRI features with multiple sclerosis (MS), necessitating differential diagnosis.

Purpose of the Study:

• To determine the frequency of CYP7B1 gene mutations in patients diagnosed with multiple sclerosis (MS).
• To investigate the potential role of CYP7B1 variants in the pathogenesis of MS.

Main Methods:

• A cohort of 117 MS patients with spastic paraplegia or suspected autosomal recessive inheritance was selected.
• Comprehensive mutational screening of the CYP7B1 gene was performed on the selected patient group.

Main Results:

• No homozygous mutations in the CYP7B1 gene were detected among the 117 MS patients.
• Two novel CYP7B1 variants and one known pathogenic mutation were identified in the heterozygous state.
• These heterozygous variants were found to cosegregate with pyramidal signs and autoimmune conditions in some patients.

Conclusions:

• CYP7B1 mutations are not a common cause of MS, as no homozygous mutations were found.
• Heterozygous CYP7B1 variants may act as susceptibility factors for MS or related neurological/autoimmune conditions.
• Altered cytochrome P450-7B1 enzymatic activity could disrupt oxysterol balance, potentially contributing to neurodegeneration and immune dysregulation in MS.