What is the cause?
Late-infantile variant Batten disease is caused by a genetic mistake in one of the Batten disease genes. We now know of at least eight different genes that can cause Batten disease. Those responsible for late infantile variant are usually CLN1, CLN5, CLN6, CLN7, CLN8 and CLN10. These genes code for proteins which are either soluble lysosomal proteins or proteins embedded within membranes. These diseases are inherited as autosomal recessive disorders, which means that both chromosomes carry mutations in the disease gene, and both parents are unaffected carriers. The nerve cells cannot function as they should and symptoms develop.
How is it diagnosed?
The diagnosis is usually made by histological and genetic tests on blood samples. A skin biopsy may be necessary and the abnormal storage material takes on a mixed appearance with granular osmiophilic deposits (GRODS), curvilinear bodies (CVB), rectilinear profiles (RLP), and/or fingerprint profiles (FPP). The appearance of the storage material can guide the genetic diagnostic tests in some cases.
Does it have any alternative name?
Several forms of late infantile variants have been recognised since the 1980s and different names have been used: variant late infantile NCL, early juvenile NCL, Finnish variant, Turkish variant, Indian variant, Mediterranean variant NCLs and so on.
How common is it?
1-2 children are diagnosed with late-infantile variant Batten disease each year in the UK. We estimate there are less than 10 affected children in the UK. Children have been diagnosed in many countries and from a variety of ethnic backgrounds.
How does the disease progress?
Children are healthy and develop normally for the first few years of life. Children with late infantile variant NCL can be very different from each other, making the disease course difficult to predict in individual cases. The first symptoms may be apparent within the first few years of life but may not develop until after school entry. Challenging behaviour is common especially in retrospect. Slowing of developmental progress, epilepsy and later lost of thinking and learning skills should prompt diagnostic investigations, especially where vision may also be deteriorating. Vision is gradually lost at some stage but this is variable. Some children will be completely dependent on their families and carers for all their daily needs by the age of six years whereas others will lose their walking and talking much later.
Death usually occurs in childhood or during the teenage years.