This is a very rare form of NCL and only a small number of cases have been written about. There may be undiagnosed cases.
What is the cause?
The disease is caused by mutations in a gene called Cathepsin D also called CLN10, which lies on chromosome 11. CLN10 disease is inherited as an autosomal recessive disorder, which means that both chromosomes carry mutations in the CLN10 gene, and both parents are unaffected carriers. The gene was discovered in 2006. CLN10 normally direct production of a lysosomal enzyme called cathepsin D. If no enzyme is produced, symptoms start very early in life, or even before birth. If some enzyme is working, symptoms develop alter and disease progression is slower.
How is it diagnosed?
The diagnosis is usually made by enzyme (CTSD) and genetic (CLN10) tests on blood samples. Occasionally a skin biopsy may be necessary. Granular deposits are the characteristic storage body at the electron microscope level.
How does the disease progress? Genotype/phonotype correlations
CLN10 disease, congenital
Seizures occur before birth. In the newborn period the babies have refactory seizures and apnoeas. Babies may die within the first weeks of life.
CLN10 disease, late infantile
Some children with mutations in CLN10 have a later onset of symptoms and slower disease progression, like variant late infantile NCL. Children become unsteady, develop seizures and visual impairment. Later they lose skills.
Dr Ruth Williams (NCL2012 Abstract Book, Clinical Summaries, 2012)