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:

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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)

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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

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Respiratory Abnormalities

• Respiratory paradox due to diaphragmatic weakness/paralysis

• Respiratory failure

• Persistent or recurrent atelectasis (collapse of lung segments or lobes)

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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.

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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

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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)

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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

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