A) Duchenne muscular dystrophy
Also called DMD, is a genetic disease affecting different groups of muscles in the body.. DMD causes muscle cells to die, and results in the muscle becoming weak, small, and deformed. DMD usually starts in the lower limbs and pelvis, and moves quickly to other muscles. It is rarely found in girls, and boys are usually the only ones affected. The disorder is produced by a gene mutation on the X chromosome.
The genetic testing is done by doing PCR on the blood
B) Spinal Muscular Atrophy (SMA)
A rare neuromuscular disorder that results in the loss of motor neurons and progressive muscle wasting. It is usually diagnosed in infancy or early childhood and if left untreated it is the most common genetic cause of infant death. It may also appear later in life and then have a milder course of the disease. The common feature is progressive weakness of voluntary muscles, with arm, leg and respiratory muscles being affected first. Associated problems may include poor head control, difficulties swallowing, scoliosis, and joint contractures. Spinal muscular atrophy is due to an abnormality (mutation) in the SMN1 gene which encodes SMN, a protein necessary for survival of motor neurons. Loss of these neurons in the spinal cord prevents signalling between the brain and skeletal muscles. Another gene, SMN2, is considered a disease modifying gene, since usually the more the SMN2 copies, the milder is the disease course. The diagnosis of SMA is based on symptoms and confirmed by genetic testing.
Usually, the mutation in the SMN1 gene is inherited from both parents in an autosomal recessive manner, although in around 2% of cases it occurs during early development (de novo). The incidence of spinal muscular atrophy worldwide varies from about 1 in 4,000 births to around 1 in 16,000 births, with 1 in 7,000 and 1 in 10,000 commonly quoted for Europe and the US respectively.
Gene Testing is done by doing PCR on the blood
