Fabry disease is a rare, progressive genetic disorder characterized by a defective gene (GLA) that causes an enzyme deficiency. This enzyme is responsible for breaking down disease substrate that, when deficient in patients with Fabry disease, builds up in the kidneys, one of the organ systems impacted by Fabry disease.
Pompe disease is a Lysosomal Storage Disorder (LSD) that results from a deficiency in an enzyme, GAA. Signs and symptoms of Pompe disease can be severe and debilitating and include progressive muscle weakness throughout the body, particularly the heart and skeletal muscles. This leads to accumulation of glycogen in cells, which is believed to result in the clinical manifestations of Pompe disease. Pompe disease ranges from a rapidly fatal infantile form with severe cardiac involvement to a more slowly progressive, late-onset form primarily affecting skeletal muscle. All forms are characterized by severe muscle weakness that worsens over time. In the early-onset form, patients are usually diagnosed shortly after birth and often experience enlargement of the heart and severe muscle weakness. In late-onset Pompe disease, symptoms may not appear until late childhood or adulthood and patients often experience progressive muscle weakness. It is estimated that Pompe disease affects approximately 5,000 to 10,000 people worldwide.
Batten disease is the common name for a broad class of rare, fatal, inherited disorders of the nervous system also known as neuronal ceroid lipofuscinoses, or NCLs. In these diseases, a defect in a specific gene triggers a cascade of problems that interferes with a cell’s ability to recycle certain molecules. The disease has several forms with similar features and symptoms but vary in severity and age of onset. Each form is caused by a mutation in a different gene. Most forms of Batten disease/NCLs usually begin during childhood. The first symptom is usually progressive vision loss in previously healthy children followed by personality changes, behavioral problems and slow learning. Seizures commonly appear within 2-4 years of vision loss. Seizures and psychosis can appear at any time during the course of disease. Progressive loss of motor functions and eventually, those affected become wheelchair-bound, are bedridden, and die prematurely.
CDKL5 Deficiency Disorder (CDD)
CDKL5 (cyclin-dependent kinase-like 5) is a gene on the X-chromosome encoding the CDKL5 protein that regulates the expression of several essential proteins for normal brain development. Genetic mutations in the CDKL5 gene result in CDKL5 protein deficiency and the disorder manifests clinically as persistent seizures starting in infancy, followed by severe impairment in neurological development. Most children affected by CDD cannot walk or care for themselves and may also suffer from scoliosis, visual impairment, sensory issues, and gastrointestinal complications.
CDKL5 mutations have been found in children diagnosed with cerebral palsy and autism, among other conditions, and the disorder was previously classified as atypical Rett Syndrome, an early seizure variant of Rett Syndrome. CDD is now considered as an independent disorder with its own distinctive characteristics.