SMA Screen
Testing for homozygous and heterozygous deletions of exon 7 of the SMN1 gene associated with the development of spinal muscular atrophy (5q SMA) in human biological material by real-time PCR. Category «Genetics»
SMA Screen
Spinal muscular atrophy (SMA) is an inherited disorder characterized by progressive degeneration of motor neurons in the anterior horns of the spinal cord. This process leads to symmetrical skeletal muscle atrophy and progressive muscle weakness.
The main cause of SMA is mutations in the SMN1 gene (5q13.2), which encodes the survival motor neuron (SMN) protein. This protein is essential for the functioning and survival of motor neurons. Its deficiency, caused by damage to the SMN1 gene, triggers their progressive degeneration and death.
Characteristics of the disease:
- Autosomal recessive inheritance. The disease develops only when two defective copies of the SMN1 gene are inherited, one from each parent.
- Carrier status. Individuals with one functional and one mutated copy of the gene are healthy carriers. The SMN protein produced from a single normal copy is sufficient for normal motor neuron function.
- Prevalence. The carrier frequency in the Russian Federation is 1 in 36 individuals.
Forms of diseases
The disease is classified into several types based on the age of onset and the severity of clinical manifestations:
- SMA type 0 (prenatal form). The most severe form of the disease. Symptoms (reduced fetal movement, severe hypotonia) are observed in utero or immediately after birth. Respiratory failure develops.
- SMA type I (Werdnig–Hoffmann disease). It manifests from birth to 6 months of age. Motor impairments include the inability to hold up the head, roll over, or sit unsupported.
- SMA type II (intermediate form). Disease onset occurs at 6–18 months of age. Patients are able to sit unsupported and hold up their head independently. Severe scoliosis develops.
- SMA type III (Kugelberg–Welander disease). Disease onset ranges from 18 months of age to adolescence. Patients retain the ability to walk independently, but progressive muscle weakness is observed.
- SMA type IV (adult form). Disease onset occurs after 20–30 years of age. It is characterized by slow progression of symptoms and, as a rule, does not lead to reduced life expectancy.
Early diagnosis of SMA is important for several reasons:
- Prevention of the birth of an affected child. Identification of carrier status in parents makes it possible to assess the risks and use prenatal (during pregnancy) or preimplantation (during in vitro fertilization) genetic diagnosis.
- To achieve the best possible clinical response, pathogenetic therapy is recommended as soon as possible after diagnosis.
Indications
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Confirmation of the diagnosis in patients with a clinical presentation characteristic of spinal muscular atrophy. -
Carrier screening for SMN1 deletion in couples planning a pregnancy. -
Prenatal diagnosis in families with an established risk of having a child with SMA.
SMA Screen
The SMA Screen Genotyping REAL-TIME PCR Kit is an in vitro Nucleic Acid Test (NAT) – human genotyping-based product.
The SMA Screen Genotyping REAL-TIME PCR Kit is designed to detect homozygous and heterozygous deletions of exon 7 of the SMN1 gene associated with development of spinal muscular atrophy (SMA 5q) in human biological material (whole blood) by real-time PCR.
Sample: Whole blood
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