Furthermore, recent studies have also implied the proteins role in cathepsin D deficiency; the overexpression of the defective protein appears to have significant effects on cathepsin D processing, with implications suggesting that accumulation of ATP synthase subunit C would result. Only recently have studies of human patients shown deficiency of lysosomal aspartyl proteinase cathepsin D.

Adult dominant form
Between 1.3 and 10% of cases are of the adult form. The age at onset is variable (6–62 yr). Two main clinical subtypes have been described: progressive myoclonus epilepsy (type A) and dementia with motor disturbances, such as cerebellar, extrapyramidal signs and dyskinesia (type B). Unlike the other NCLs, retinal degeneration is absent. Pathologically, the ceroid-lipofuscin accumulates mainly in neurons and contains subunit C of the mitochondrial ATP synthase.Two independent families have been shown to have mutations in the DNAJC5 gene – one with a transversion and the other with a deletion mutation. The mutations occur in a cysteine-string domain, which is required for membrane targeting/binding, palmitoylation, and oligomerization of the encoded protein cysteine-string protein alpha (CSPα). The mutations dramatically decrease the affinity of CSPα for the membrane. A second report has also located this disease to this gene. Treatment
Currently, no widely accepted treatment can cure, slow down, or halt the symptoms in the great majority of patients with NCL, but seizures may be controlled or reduced with use of antiepileptic drugs. Additionally, physical, speech, and occupational therapies may help affected patients retain functioning for as long as possible. Several experimental treatments are under investigation.
Animal models of late infantile NCL showed that the AAVrh.10 delivery system "was much more effective, giving better spread of the gene product and improving survival greatly".A third gene therapy trial, using the same AAVrh.10 delivery system, began in 2011 and has been expanded to include late infantile NCL patients with moderate tosevere impairment or uncommon genotypes, and uses a novel administration method that reduces general anesthesia time by 50% to minimize potential adverse side effects. Flupirtine
A painkiller available in several European countries, flupirtine, has been suggested to possibly slow down the progress of NCL, particularly in the juvenile and late infantile forms. No trial has been officially supported in this venue, however. Currently, the drug is available to NCL families either from Germany, Duke University Medical Center in Durham, North Carolina, or the Hospital for Sick Children in Toronto. Stem cells
On October 20, 2005, the Food and Drug Administration approved a phase-I clinical trial of neural stem cells to treat infantile and late infantile Batten disease. Subsequent approval from an independent review board also approved the stem cell therapy in early March 2006. This treatment will be the first transplant of fetal stem cells performed on humans. The therapy is being developed by Stem Cells Inc and is estimated to have six patients. The treatment was to be carried out in Oregon.Juvenile NCL has recently been listed on the Federal Clinical Trials website to test the effectiveness of bone-marrow or stem-cell transplants for this condition.