What is SMA?

SMA (Spinal Muscular Atrophy) is a neurological condition and a type of motor neuron disease which a person cannot control the movement of their muscles due to a loss of nerve cells in the spinal cord and brain stem. A person with SMA is unable to move, walk, eat or breathe without assistance.

What causes SMA?

SMA is caused by a mutation in the survival motor neuron gene 1 (SMN1 gene). Motor neurons are the nerve cells that control movement. Abnormal SMN1 gene leads to missing neuron protein critical for nerve function & muscle control.

Types of SMA

What is SMA Carrier?

SMA carrier is a person that has a mutant gene of SMA disease who usually does not display or show symptoms of the disease.

若父母亲同时为同一种疾病的带因者，小孩就可能同时遗传到双方的异常基因而患病，且隐性遗传病难以透过一般常规产前检测发现，因此常到了出生后才被发现异常。

If both parents are SMA carrier, there is a 25% risk that the offspring have the recessive trait in phenotype.

Expanded Carrier Screening适合对象：

• Have a family history of SMA disease.
• Both partners are carriers of SMA.
• 血缘关系较近的夫妻

Sample Requirement:

• Amniotic fluid 15ml