Definition:
Finnish Variant Late Infantile CLN5 disorder is part of a group of progressive degenerative neurometabolic disorders known as neuronal ceroid lipofuscinoses (NCLs). NCLs are characterized by an abnormal accumulation of lipopigaments, subtances combined of fats and proteins within the brain’s nerve cells, eyes, skin, muscle, and within other tissues throughout the body.

Although this disorder has many clinical symptoms similar to other NCLs, it is distinct because its cause is known. The cause of many NCLs remains nebulous. Finnish Variant Late Infantile CLN5 disorder is caused by a mutation on the CLN5 gene, which leads to an accumulation of transmembrane proteins in the cells. This mutation essentially eliminates the function of the CLN5 gene and gives rise to the symptoms of this disorder. The disorder causes nerve cells, found in the brain, retina, and in the central nervous system, to die.

Finnish Variant Late Infantile CLN5 predominately affects individuals of Finnish origin. It is estimated that one in 100 individuals in Finland are gene carriers of an NCL disorder. The exact frequency of Finnish Variant Late Infantile CLN5 in Finland or in the United States is not known. It is estimated that the NCLs affect two to four of every 100,000 live births in the United States.

Symptoms:
Symptoms of Finnish Variant Late Infantile CLN5 begin between two and seven years of age. The loss of muscle coordination and progressive mental deterioration are symptoms typical of this disorder. Loss of vision and seizures are also common symptoms as this disorder progresses.

Inheritance Pattern:
Finnish Variant Late Infantile CLN5 is an autosomal recessive disorder.

Life Expectancy:
The life Expectancy for Finnish Variant Late Infantile CLN5 is between 13 and 30 years of age.

Diagnosis and Testing:
A DNA analysis can confirm a mutation on the CLN5 Gene, and therefore, a diagnosis of Finnish Variant Late Infantile CLN5. For this analysis, blood or tissue sample is tested from individuals who are suspected of having the disorder and/or from members of families wherein a carrier of the CLN5 gene has been identified. Prenatal screening is also available.

Treatment:
There is no cure for Finnish Variant Late Infantile CLN5. Treatment is limited to reducing or controlling the symptoms of this disorder with regular consultation with neurologists, ophthalmologists, and genetic counselors. Neurologists are able to help control seizures or nervous system complications. An ophthalmologist can monitor vision loss, and physical and occupational therapists can assist the affected individual to maintain muscle movement and reduce muscle discomfort.