Glycogen Storage Disease, Type II (GAA)
Glycogen storage disease type II, also known as Pompe disease, is an autosomal recessive disorder that is caused by pathogenic variants in the gene GAA. While it is found in populations worldwide, it is most prevalent in individuals of Ashkenazi Jewish or African descent. Symptoms can manifest in infancy or later in life. There are two main forms of the disease. Infantile-onset disease is characterized by poor feeding and failure to thrive, hypotonia, and an enlarged heart. If untreated, the cardiac manifestations usually cause death in the first year of life. A variant form of the infantile-onset disease has a slower progression, with death in occurring in childhood. Enzyme replacement therapy may slow the disease progression. Late-onset disease can begin any time after infancy. These patients do not usually have cardiac problems, but have muscle weakness and difficulty breathing. Patients may reach adulthood, but life expectancy is reduced. Specific variants have been associated with the infantile-onset or late-onset forms; however, the correlation is not always absolute, and some variants do not have a known genotype-phenotype correlation.
For information about carrier frequency and residual risk, please see the residual risk table.