<unk>  is diagnosed using genetic testing that detects homozygous deletion of the SMN1 gene in over 95% of cases, and a compound SMN1 mutation in the remaining patients. Genetic testing is usually carried out using a blood sample, and MLPA is one of more frequently used genetic testing techniques, as it also allows establishing the number of SMN2 gene copies, which has clinical importance. Symptomatically,<unk>  can be diagnosed with a degree of certainty only in children with the acute form who manifest a progressive illness with paradoxical breathing, bilateral low muscle tone and absent tendon reflexes. Early diagnosis Early diagnosis of<unk> , at the asymptomatic stage of the disease, allows for Preimplantation testing Preimplantation genetic diagnosis can be used to screen for<unk> -affected embryos during in-vitro fertilisation. Prenatal testing Prenatal testing for<unk>  is possible through chorionic villus sampling, cell-free fetal DNA analysis and other methods. Newborn screening Routine newborn screening for<unk>  is becoming increasingly commonplace in developed countries, given the availability of causative treatments that are most effective at the asymptomatic stage of the disease. In 2018, newborn screening for<unk>  was added to the US list of recommended newborn screening tests and as of April 2020 it has been adopted in 39 US states. As of May 2021,<unk>  newborn screening has been implemented in Taiwan and is in the course of implementation in Australia, Belgium, Canada, France, Germany, Netherlands, Poland, Serbia and Slovenia. Additionally, pilot projects are being conducted in Australia, China, Italy, and Japan. Carrier testing Those at risk of being carriers of SMN1 deletion, and thus at risk of having offspring affected by<unk> , can undergo carrier analysis using a blood or saliva sample. The American College of Obstetricians and Gynecologists recommends all people thinking of becoming pregnant be tested to see if they are a carrier. The carrier frequency of<unk>  is comparable to other disorders like thalassemia and in a north Indian cohort has been found to be 1 in 38. However, genetic testing will not be able to identify all individuals at risk since about 2% of cases are caused by de novo mutations and 5% of the normal population have two copies of SMN1 on the same chromosome, which makes it possible to be a carrier by having one chromosome with two copies and a second chromosome with zero copies. This situation will lead to a false negative result, as the carrier status will not be correctly detected by a traditional genetic test.
Spinal muscular atrophy
Prader–Willi syndrome
Spinal and bulbar muscular atrophy
Duchenne muscular dystrophy
Madras motor neuron disease
Congenital muscular dystrophy
Muscular dystrophy
Distal spinal muscular atrophy type 1