Table 1 The symptoms of four types of SMA and the SMA-discordant sibs
System | Symptoms (HPO) | Type I SMA (OMIM:253300) | Type II SMA (OMIM:253550) | Type III SMA (OMIM:253400) | Type IV SMA (OMIM:271150) | Patient1 (Male) | Patient2 (Female) |
|---|---|---|---|---|---|---|---|
Musculature | Spinal muscular atrophy (HP:0007269) | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ |
Proximal amyotrophy (HP:0007126) | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | |||
Proximal muscle weakness (HP:0003701) | ✓⎕ | ✓⎕ | ✓⎕ | ||||
Skeletal muscle atrophy (HP:0003202) | ✓⎕ | ✓⎕ | |||||
EMG: neuropathic changes (HP:0003445) | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | |
Muscle weakness (HP:0003445) | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | |||
Muscle cramps (HP:0003394) | ✓⎕ | ||||||
Cardiovascular | Atrial septal defect (HP:0001631) | ✓⎕ | |||||
Ventricular septal defect (HP:0001629) | ✓⎕ | ||||||
Nervous System | Tongue fasciculations (HP:0001308) | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ |
Areflexia (HP:0001284) | ✓⎕ | ✓⎕ | |||||
Degeneration of anterior horn cells (HP:0001284) | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | Unknown | Unknown | |
Hand tremor (HP:0002378) | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | |||
Hyporeflexia (HP:0001265) | ✓⎕ | ||||||
Respiratory System | Respiratory failure (HP:0002878) | ✓⎕ | ✓⎕ | ||||
Respiratory insufficiency (HP:0002093) | ✓⎕ | ✓⎕ | |||||
Limbs | Proximal muscle weakness in lower limbs (HP:0008994) | ✓⎕ | ✓⎕ | ||||
Limb fasciculations (HP:0007289) | ✓⎕ | ||||||
Areflexia of lower limbs (HP:0002522) | ✓⎕ | ✓⎕ | |||||
Immunology | Recurrent respiratory infections (HP:0002205) | ✓⎕ | ✓⎕ | ✓⎕ | |||
Prenatal and Birth | Decreased fetal movement (HP:0001558) | ✓⎕ | |||||
Inheritance | Autosomal recessive inheritance (HP:0000007) | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ | ✓⎕ |
Others | Age of onset | 0–6 months | 7–18 months | > 18 months | > 21 years | 3 years old | At birth |
Highest function achieved | Never sit | Sit, never stand | Stand and walk | Walk during adulthood | Stand and walk | Never sit |