Gene therapy trial for Duchenne Muscular Dystrophy

dmd

Duchenne and Becker muscular dystrophy are both caused by mutations in the same dystrophin gene.

How it this possible?

Well, the genetic code which is translated to from proteins “talks” in words made of three letters (base pairs).

dmd dna

A gene mutation that deletes only one or two base pairs, or worse still signals the end of the word (known a “premature stop codon”) will result it a very abnormal dysfunctional gene product, leading to complete deficiency of functioning dystrophin, and the more severe Duchenne Muscular Dystrophy.

dmd muscle bx

Normal muscle bx (a) vs Duchenne muscular dystrophy (b) with complete absence of dystrophin (d)

However a gene mutation (deletion) that removes base pairs in a multiples of three is called an in-frame mutation, and causes a (sometimes only minor) qualitative change in the dystrophin protein, leading to the milder Becker’s muscular dystrophy.

Ataluren (also known as PTC124) is a small molecule designed to overcome premature stop codons.

alturen

Put simply, the idea is that it might convert some Duchenne boys in to a milder form (more like Becker’s) of muscular dystrophy by allowing them to produce some more normal dystrophin.

The drug can only help boys affected with premature stop codons confirmed by DNA testing.

The drug is currently undergoing Phase III trialsClick here for more information.

Advertisements

New study compares steroid regimens in boys with Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) affects 1 in 3,600 boys and is caused by a mutation in the dystrophin gene, resulting in progressive muscle weakness.

Affected male children are normal at birth, but develop signs of muscle weakness before age 6, usually first affecting the legs and pelvis, causing difficulty getting up from the floor or a sitting position, and difficulty climbing stairs. Untreated boys are usually wheelchair dependent by age 12.

Ongoing research is leading towards pre-symptomatic diagnosis of DMD, and there has been some progress in genetic therapy for affected boys identified in these early stages of the disease.

However, so far corticosteroid therapy is the only treatment that has been shown to increase muscle strength in boys already affected with symptoms of DMD.

Steroids can cause side effects, and there is wide variability whether doctors doctors prescribe prednisone or deflazacort, as well as the dosing, duration of steroid use or even whether steroids are prescribed at all.

A new study aims to answer some of these questions.

The study is looking to enroll boys aged 4-7 with genetically confirmed DMD who have not taken steroids before.

They will be included in the study for 3-5 years and receive either:
1. Prednisone 0.75mg/Kg/d, or
2. Prednisone 0.75mg/Kg/d 10days on then 10 days off, or
3. Deflazacort 0.9mg/Kg/d

They will need hospital visits every 3 months for the first 6 months, then every 6 months thereafter.

This study is available locally at Penn Sate Hershey Medical Center – parents or physicians of interested patients should contact Beth Stephens at 717-531 0003 extension 283395 or by email for more information.

New Monmouth Neuroscience Clinic Space

125th-annv-logo-blue-and-gray

The Neuroscience Institute at Monmouth Medical Center is proud to announce the opening of its brand new out-patient clinic space on the 4th floor of the Wimpfheimer building, which will will be the home of many new  innovative programs.

View of Monmouth from Third Ave, showing Winpfheimer building (center).

View of Monmouth from Third Ave, showing Wimpfheimer building (center).

This historical building was erected in 1919 with money donated by board of trustee member Charles A. Wimpfheimer, in memory of his 19-year old son Jacques, who when stricken with pneumonia while in military service requested that he be given the same treatment as the other privates, and as a result was sent to a ward in a Hoboken hospital, where he died.

wimp-plaque

MMC clinic

DIRECTIONS:
Click here for directions to Monmouth Medical Center.

Once you arrive, enter the hospital from 3rd Avenue (1), park (2) and enter the hospital via the Radiation-Oncology Entrance (3).  Register at the desk:

MMC map

You will be directed to elevators that will bring you up to the 4th floor (BBR4), where you will pass through a nursing evaluation, then proceed to out brand new out-patient space on Wimpfheimer 4.

Multifocal Motor Neuropathy

Multifocal motor neuropathy (MMN) with conduction block is an acquired immune-mediated demyelinating neuropathy, which causes slowly progressive weakness, fasciculations, and cramping. It can resemble amyotrophic lateral sclerosis (ALS) with predominant lower motor neuron involvement, but distinction is important since MMN usually improves with immunosuppressive treatment.

MMN is more common in men than women with a mean age at onset of 40 years (range of 20–70). The most common initial symptoms are wrist drop, grip weakness, and foot drop. Weakness progresses asymmetrically, but usually remains more prominent in the arms than in the legs. Weakness is typically more pronounced than would be suggested by the degree of muscle atrophy present. Affected patients also complain of muscle cramps and fasciculations. Tendon reflexes are reduced in affected regions. Sensory complaints are unusual.

These symptoms and signs from MMN are very similar to those seen in early ALS, and many patients are initially misdiagnosed with this disorder. MMN can usually be distinguished from ALS by its more slowly progressive disease course, the absence of upper-motor-neuron signs such as spasticity and hyperreflexia and the lack of difficulty with speech and swallowing.

However a carefully planned and executed electrodiagnostic study (EMG) is critical for distinguishing these disorders. MMN is a demyelinating neuropathy, while ALS is an anterior horn cell (motor neuronopathy) which causes secondary axonal degeneration of the motor nerve. When one suspects MMN clinically, identifying partial motor conduction block is critical in confirming the diagnosis.

The presence of high titers of antibodies to GM1 ganglioside can also be useful for confirming the diagnosis of MMN, but are only present in 20-60% of patients, and are rarely present in ALS patients, underscoring the importance of clinical suspicion and the EMG for making the diagnosis.

MMN is an immune mediated disorder and strength can recover after  repeated treatments with intravenous immunoglobulin (IVIG), whereas ALS does not respond to this or any other treatment, hence the importance of distinguishing these 2 disorders:

Disease                                                           MMN                                           ALS
Distribution of weakness                        Asymmetric,Arms                Ultimately generalized
Upper motor neuron findings                 Absent                                   Usually present
EMG                                                        Conduction block                   Motor axonal loss
Anti GM1 Ab                                               20-60%                                  10%
Response to IVIG                                       Yes                                           No

The clinical pictures below are from a patient with longstanding generalized weakness that I encountered several years ago.  The first picture shows his severe upper  limb atrophy (and weakness):

MMN pre

His EMG showed conduction block, suggesting MMN:

MMN CB

And the second picture showed the clinical improvement that had already occurred after 6 monthly treatments with IVIG:

MMN post

Obviously it is important to at least consider this treatable disorder in all patients with suspected ALS or motor neuron disease, and it is very important to see a neurology specialist with additional training and certification in neuromuscular medicine and/or electrodiagnostic medicine. Click here or call 732 923-5576 to find out more about the Central Jersey MDA and Neuromuscular Center at the Monmouth Neuroscience Institute.