The diagnostic process for SMA begins when an individual presents with suspected symptoms. Initially, a detailed medical history is taken, followed by a thorough physical examination. To further investigate, the physician may order tests such as electromyography (EMG) or a muscle biopsy. A blood test to measure creatine kinase levels might also be requested, particularly for weakened muscles.
If clinical findings strongly suggest SMA (based on the child's symptoms and initial diagnostic workup), genetic testing via a blood sample is typically considered essential for confirmation. This is because genetic testing is the most definitive method for diagnosing SMA, specifically types 1 through 4, which are linked to chromosome 5 abnormalities. Over 95% of SMA diagnoses are confirmed by DNA testing revealing a specific gene deletion. The remaining cases, approximately 5%, may involve other causative mutations.