SNP Shot: Genomic Insights

CLN1 disease is a hereditary neurological disorder. Infants with CLN1 disease initially develop normally, but around 18 months, they typically become more fussy and begin to lose skills they had already learned (developmental regression). This condition causes nerve cells in the brain to gradually die, resulting in brain shrinkage (brain atrophy) and a smaller than normal head size (microcephaly). Affected children experience low muscle tone (hypotonia), intellectual disability, and motor impairment, and often struggle to speak or walk. Some develop repetitive hand motions. By the age of 2, these children often experience muscle jerks (myoclonus), repeated seizures (epilepsy), and vision impairment. Some also experience frequent respiratory infections. As the disease progresses, severe feeding problems develop, often requiring a feeding tube. Sadly, children with CLN1 disease typically do not live beyond childhood.

In some individuals, the onset of CLN1 disease symptoms is delayed until later in childhood or adulthood. Similar to younger children, older individuals experience a decline in cognitive abilities, myoclonus, epilepsy, and vision loss. Life expectancy varies depending on the age of symptom onset and the severity of the condition; some individuals may only survive into their teens or adulthood. Adults with CLN1 disease may also develop movement problems, such as ataxia (poor coordination) or parkinsonism (a group of movement abnormalities).

CLN1 disease belongs to a group of neurological disorders called neuronal ceroid lipofuscinoses (NCLs), also known as Batten disease. These disorders affect the nervous system and lead to progressive problems with vision, movement, and cognitive function. NCLs are distinguished by their underlying genetic cause. Each type is named "CLN," short for ceroid lipofuscinosis, neuronal, followed by a number indicating the specific subtype.

Inheritance:

CLN1 disease is inherited in an autosomal recessive manner. This means that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. The parents, who each carry one copy of the mutated gene, are typically unaffected carriers of the disease.