LEARN MORE ABOUT SMARD1, CMT2S, AND IGHMBP2 DISORDERS

#smashSMARDchallenge

Symptoms of SMARD1 typically present in infancy, but there is a significant amount of variability in the timing of onset, and numerous SMARD1 patients have been diagnosed later in childhood. While the mechanism is not yet well understood, the underlying pathology is cellularly different than the more commonly known SMA. The diseases are entirely different.

A variety of other symptoms and physical findings can develop in individuals with SMARD1:

Prenatal/Natal Features

Intrauterine growth retardation (IUGR) / SGA (Small for gestational age)
Premature birth
Reduced fetal movements
Birth weight, length and head circumference values less than the 10th percentile (small for their gestational age)
Inability to gain weight or grow at the expected rate (failure to thrive)

Underreported Abnormalities:

Liver Enzyme Elevation (AST & ALT)
Undescended Testicles (cryptorchidism)
Hematological Abnormalities (Hemolysis on manual blood smears)
Carbohydrate Metabolism Abnormalities
Typically presents with a metabolic acidosis
Electrolyte Abnormalities

Respiratory Abnormalities

Respiratory paradox due to diaphragmatic weakness/paralysis
Respiratory failure
Persistent or recurrent atelectasis (collapse of lung segments or lobes)

Orthopedic abnormalities

Distal extremity deformities, such as clubfoot (talipes equinovarus)
Permanent flexion of the finger (camptodactyly of finger)
Front half of the foot turning inward (metatarsus varus)
Limitation of the range of motion of joints (joint contractures) in hands or feet (hand/foot arthrogryposis)
- Wrist retraction
- Elbow, ankle, and knee stiffness
Curved/bent fingers or toes (claw hands or toes)
Elbow, ankle, and knee stiffness.

Gastrointestinal features

Excessive production of saliva (hyper salivation)
Difficulty swallowing (dysphagia)
Gastroesophageal reflux (persistent spitting up)
Inability of the stomach to empty food in the usual way (gastroparesis)
Inability to empty the bladder (urinary retention)
Constipation
Gastric Volvulus
TPN Dependency

Neuromuscular features

Fatty finger pads
Loss of nerve supply to the diaphragm (denervation of the diaphragm)
Abnormal elevation of the diaphragm (diaphragmatic eventration)
Muscle wasting of arms and legs
Spinal muscle deterioration (spinal muscular atrophy)
Decreased nerve conduction velocity (slowed ability for nerves to send messages to parts of body)

Other Characteristics

Thoracospinal deformities (scoliosis, thoracic dystrophy)
Seizures occurring during or after a hypoxic or anoxic (little to no oxygen) episode
High blood pressure
Tachycardia
Dislocated hip

Click to learn more about SMARD from NORD (the National Organization for Rare Disorders)

How does a child "get" SMARD?

SMARD is a disease that is inherited in a recessive pattern, meaning both parents must be carriers of the gene mutation and each parent must pass on a copy of the mutation for the child to be affected.

Therefore, every time two carriers have a baby, there is a 1 in 4 or 25% chance they will have an affected baby.

The mutations that cause SMARD are located on the IGHMBP2 gene. Each child usually has a unique combination of gene mutations, which is why there can be variability in onset and presentation as well as severity of disease.

What are the symptoms of SMARD?

Decreased fetal movements
IUGR (low birth weight)
Preterm birth
Weak cry
Feeding difficulties and poor weight gain
Sudden respiratory distress in an otherwise healthy infant
Muscle weakness (usually greater in the lower extremities and distal muscles)
Elevated heart rate
Excessive sweating
Tachypnea (rapid breathing)
Clenched fists
Foot drop or clubbed feet
Typical age of onset is between 6 weeks and 6 months of age
Cognitive function is usually unaffected

How Common is SMARD?

SMARD is extremely rare. It has been diagnosed in approximately 100 children in the world, but the exact number of cases is unknown.

It is considered an orphan disease. Information and resources are hard to find, and there are only a handful of research articles available for review.

If you've recently had a child diagnosed with SMARD, please reach out to us! At this point, families of patients may know more about the disease than your doctor. At the very least, our parent group can offer support and hope for a happy future.

What is the prognosis of SMARD?

Many children die in the first year of life, often in their sleep or from a respiratory illness.

Almost all who are living with SMARD past 1 year of age require a tracheostomy and are ventilator and wheelchair dependent.

The degree of muscle weakness varies from child to child.

There is not enough research to predict life expectancy for those patients who choose mechanical ventilation, but there are dozens of children and a few adults with SMARD who are living happy, full lives.

How does SMARD differ from SMA?

SMARD and SMA both affect the lower motor neuron cells of the spinal cord that control voluntary muscle activities like swallowing, breathing, walking and talking.

Both are often said to be like "ALS in babies". The main differences are that SMARD is caused by mutations in the IGHMBP2 gene and SMA (which can range from type 1-4) is caused by mutations in or the absence of the SMN1 gene

SMARD presents as a baby in respiratory distress that gradually becomes "floppy" and SMA usually presents as a "floppy" baby who gradually develops respiratory distress

Is there a treatment or cure for SMARD?

Unfortunately, no. Treatment at this point is limited to managing symptoms by way of mechanical ventilation and maintaining a clear airway, as well as physical therapy to try to retain muscle function.

Gene therapy is a well documented treatment for this disease in animal models. The plan is to translate this promising data into a human clinical trial in the near future.

Currently, however, funding is limited because of the small patient population. This is where the mission for smashSMARD was born.

Though the SMARD community is small, it is mighty, and committed to finding a cure.