NORD gratefully acknowledges Sandra Hofmann, MD, PhD, Professor, Internal Medicine, Molecular Genetics, University of Texas Southwestern Medical Center, for assistance in the preparation of this report.
Classic infantile CLN1 disease is a rare genetic disorder with an onset of symptoms between 6 and 24 months of age. CLN1 disease is characterized by delays in reaching developmental milestones (developmental delays), twitching or jerking of muscles (myoclonic jerks), seizures, and mild to moderate intellectual disability. As children age, the psychomotor abilities (abilities that require coordination of muscular and mental activity) will deteriorate. Progressive vision loss leading to blindness can also occur. The severe form of CLN1 disease is often fatal during childhood. However, some children do not become ill until later because their genetic defect does not completely abolish the function of the gene and their disease can appear very much like juvenile CLN3 disease.
Classic infantile CLN1 disease belongs to a group of progressive degenerative neurometabolic disorders known as the neuronal ceroid lipofuscinoses (NCLs). These disorders share certain similar symptoms and are distinguished in part by the age at which such symptoms appear. Classic infantile CLN1 disease was previously called infantile neuronal ceroid lipofuscinosis or Santavuori disease. The NCLs are characterized by abnormal accumulation of certain fatty, granular substances (i.e., pigmented lipids [lipopigments] ceroid and lipofuscin) within nerve cells (neurons) of the brain as well as other tissues of the body that may result in progressive deterioration (atrophy) of certain areas of the brain, neurological impairment, and other characteristic symptoms and physical findings.
The neuronal ceroid lipofuscinoses are further classified as lysosomal storage diseases. Lysosomal storage diseases are inherited metabolic diseases that are characterized by an abnormal build-up of various toxic materials in the body's cells because of enzyme deficiencies. There are more than 50 of these disorders altogether, and they may affect different parts of the body, including the skeleton, brain, skin, heart, and central nervous system. New lysosomal storage disorders continue to be identified. While clinical trials are in progress on possible treatments for some of these diseases, there is currently no approved treatment for many lysosomal storage diseases.
(Please note that some of these organizations may provide information concerning certain conditions potentially associated with this disorder [e.g., seizures, visual impairment, etc.].)
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