World Rare Disease Day 2025: Focus on SMA and Light Up the Spark of Life

Today is the?"World Rare Disease Day". This year's theme is "More Than Rare". Although rare diseases have a low incidence rate, the number of patients globally is as high as 300 million, and 80% of them are genetic diseases. Currently, there are more than 7,000 identified rare diseases.Today, we will focus on a rare disease - spinal muscular atrophy (SMA), and explore the significant importance of SMN1 gene testing and screening.

1. Introduction to Rare Diseases

Rare diseases refer to diseases whose number of patients accounts for 0.065% - 0.1% of the total population. Most of them are congenital and chronic diseases, often endangering lives. Despite the low incidence rate of each single disease, due to the large variety (more than 6,000 types), the total number of rare disease patients is huge. In recent years, with the progress of medical technology and the increase of social attention, remarkable progress has been made in the diagnosis and treatment of rare diseases, but there are still problems such as difficult diagnosis and expensive treatment.

2. Introduction to SMA

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease, mainly caused by the deletion or mutation of the survival motor neuron 1 (SMN1) gene. The SMN1 gene is responsible for encoding the SMN protein, which is crucial for the survival of motor neurons. A defect in the SMN1 gene will lead to a deficiency of the SMN protein, which in turn causes the degeneration of spinal anterior horn motor neurons, manifested as progressive muscle weakness and muscle atrophy. SMA is the number one genetic disease killer for infants under 2 years old, with an incidence rate of approximately 1 in 10,000, and the carrier frequency is 1 in 40 to 1 in 50610. The clinical manifestations of SMA vary according to the age of onset and the speed of disease progression, and it is usually divided into five types:

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3. SMN1 Gene Detection Loci and Significance

The SMN1 gene is located on chromosome 5, and the homozygous deletion of exon 7 is the pathogenic cause for 95% of SMA patients. Gene testing showing a homozygous deletion mutation or biallelic mutation of exon 7 of SMN1, a positive result can confirm the diagnosis of SMA. SMN1 gene testing can clearly diagnose SMA patients, carriers, and normal people by analyzing the copy number of exon 7. The significance of the detection includes:

● Early diagnosis: Through neonatal screening or prenatal diagnosis, detect SMA infants as early as possible and carry out timely intervention and treatment.

● Carrier screening: Help reproductive-age couples understand their own carrier status and assess the reproductive risk.

● Disease classification and prognosis assessment: Combined with the copy number of the SMN2 gene, predict the severity of the disease and the treatment effect.

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4. Applicable Population for SMN1 Gene Detection

Although SMA is a severe single-gene genetic disease, its genetic pattern is clear, the pathogenic cause is definite, and clinical diagnosis and treatment are feasible, meeting the tertiary prevention strategy for birth defects.

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5. Conclusion

Although SMA is a rare disease, there are many carriers, and it is seriously harmful. Through SMN1 gene testing, we can achieve early diagnosis, scientific prevention, and precise treatment, bringing hope to SMA patients and their families. On World Rare Disease Day in 2025, let's pay attention to rare diseases together and light up the light of life!