Distal hereditary motor neuronopathy of the Jerash type is caused by a novel SIGMAR1 c.500A>T missense mutation

BACKGROUND

Distal hereditary motor neuronopathies (dHMN) are a group of genetic disorders characterised by motor neuron degeneration leading to muscle weakness that are caused by mutations in various genes. HMNJ is a distinct form of the disease that has been identified in patients from the Jerash region of Jordan. Our aim was to identify and characterise the genetic cause of HMNJ.

METHODS

We used whole exome and Sanger sequencing to identify a novel genetic variant associated with the disease and then carried out immunoblot, immunofluorescence and apoptosis assays to extract functional data and clarify the effect of this novel SIGMAR1 mutation. Physical and neurological examinations were performed on selected patients and unaffected individuals in order to re-evaluate clinical status of patients 20 years after the initial description of HMNJ as well as to evaluate new and previously undescribed patients with HMNJ.

RESULTS

A homozygous missense mutation (c.500A>T, N167I) in exon 4 of the SIGMAR1 gene was identified, cosegregating with HMNJ in the 27 patients from 7 previously described consanguineous families and 3 newly ascertained patients. The mutant SIGMAR1 exhibits reduced expression, altered subcellular distribution and elevates cell death when expressed.

CONCLUSION

In conclusion, the homozygous SIGMAR1 c.500A>T mutation causes dHMN of the Jerash type, possibly due to a significant drop of protein levels. This finding is in agreement with other SIGMAR1 mutations that have been associated with autosomal recessive dHMN with pyramidal signs; thus, our findings further support that SIGMAR1 be added to the dHMN genes diagnostic panel.

Sixth nerve palsy and sphenoidal sinusitis

Sphenoid sinusitis is an uncommon infection that accounts for approximately 3% of all cases of acute sinusitis. It is usually accompanied by pansinusitis; less commonly it occurs alone. We are presenting a case of a 30 year old young male patient who presented with three weeks history of headache, along with blurry vision and diplopia. Neurological examination showed evidence of bilateral sixth nerve palsy. Brain magnetic resonance imaging showed evidence of pansinusitis, including sphenoidal sinusitis. Cerebrospinal fluid studies showed no evidence of meningitis.

Subdural hematoma complicating middle fossa arachnoid cyst

We report a case of a middle aged patient with middle fossa arachnoid cyst that was complicated by subdural hematoma. This was demonstrated by magnetic resonance imaging that remain the most useful diagnostic tool, and providing excellent tissue specificity. Patient was treated by irrigating the hematoma through burrholes. Magnetic resonance imaging in the postoperative period showed a reduction in size of the arachnoid cyst.

Alcohol with xylocaine for treatment of eyelid dystonia

Eyelid dystonia represents a form of idiopathic torsion dystonia, and it is considered as a rare disorder. Although botulinum toxin injections into the eyelids and eyebrows are considered by many neurologists as the treatment of choice for this, its cost limit its use in our community. A study was conducted at the King Hussein Medical Center between January 1995 and January 1998 using 1-2 ml of 0.5% xylocaine added to 99.5% ethanol in one-tenth of the volume of xylocaine, made injectable into the eyelids and eyebrows muscles in patients with blepharospasm. The treatment was aimed at reducing muscle spindle afferent activity. Twenty-one patients were given this modality of treatment in at least 8-12 separate sessions, with two weeks elapsing between any two sessions. Mild to moderate improvement was observed in 47.6% of our patients. The average latency from the time of the injection to the onset of improvement was 30-60 min and the average duration of improvement was 5-7 days. The commonest encountered side-effect was bruising at the site of injection that resolved spontaneously in less than 5 days. It is obvious that the usefulness of this treatment is limited by the substantially shorter duration of benefit, thus it cannot be considered as an alternative to Botox treatment. It may be useful to investigate whether a higher alcohol concentration is more effective.