The most commonly identified mutations are in the CLN3 gene, which is located on the short arm of chromosome 16 (16p12.1). The normal function of the gene is not presently known, but results in a transmembrane protein.Adult NCL may be inherited as an autosomal recessive (Kufs), or less often, as an autosomal dominant (Parrys) disorder. In autosomal dominant inheritance, all people who inherit a single copy of the disease gene develop the disease. As a result, no carriers of the gene are unaffected.Many authorities refer to the NCLs collectively as Batten disease. Diagnosis
Because vision loss is often an early sign, NCL may be first suspected during an eye exam. An eye doctor can detect a loss of cells within the eye that occurs in the three childhood forms of NCL. However, because such cell loss occurs in other eye diseases, the disorder cannot be diagnosed by this sign alone. Often, an eye specialist or other physician who suspects NCL may refer the child to a neurologist, a doctor who specializes in disease of the brain and nervous system. To diagnose NCL, the neurologist needs the patients medical history and information from various laboratory tests.Diagnostic tests used for NCLs include:

Skin or tissue sampling: The doctor can examine a small piece of tissue under a  microscope to spot typical NCL deposits. These deposits are found in many different tissues, including skin, muscle, conjunctiva, rectal and others. Blood can also be used.
Retrospectively, these papers disclose that the authors grouped together different types of the syndrome. Furthermore, Batten, at least for some time, insisted that the condition that he described was distinctly different from Tay–Sachs disease, the prototype of a neuronal lysosomal disorder now identified as GM2 gangliosidosis type A. Around the same time, Walther Spielmeyer reported detailed studies on three siblings, who have the Spielmeyer-Sjogren (juvenile) type, which led him to the very firm statement that this malady is not related to Tay–Sachs disease. Subsequently, however, the pathomorphological studies of Károly Schaffer made these authors change their minds to the extent that they reclassified their respective observations as variants of Tay–Sachs disease, which caused confusion lasting about 50 years.In 1913–14, Max Bielschowsky delineated the late infantile form of NCL. However, all forms were still thought to belong in the group of "familial amaurotic idiocies", of which Tay–Sachs was the prototype. In 1931, Torsten Sjögren, a Swedish psychiatrist and geneticist, presented 115 cases with extensive clinical and genetic documentation and came to the conclusion that the disease now called the Spielmeyer-Sjogren (juvenile) type is genetically separate from Tay–Sachs. 1950 to today
Departing from the careful morphological observations of Spielmeyer, Hurst, and Sjovall and Ericsson, Zeman and Alpert made a determined effort to document the previously suggested pigmentary nature of the neuronal deposits in certain types of storage disorders.