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.
Enalaprilat is the active metabolite of enalapril. It is the first dicarboxylate-containing ACE inhibitor and was developed partly to overcome these limitations of captopril. The thiol functional group of captopril was replaced with a carboxylic acid group, but additional modifications were required to achieve a potency similar to captopril. Enalaprilat, however, had a problem of its own. The consequence of the structural modifications was that its ionisation characteristics do not allow for sufficient GI absorption. Thus, enalaprilat was only suitable for intravenous administration. This was overcome by the monoesterification of enalaprilat with ethanol to produce enalapril. As a prodrug, enalapril is hydrolyzed in vivo to the active form enalaprilat by various esterases. Peak plasma enalaprilat concentrations occur 2 to 4 hours after oral enalapril administration. Elimination thereafter is biphasic, with an initial phase which reflects renal filtration (elimination half-life 2 to 6 hours) and a subsequent prolonged phase (elimination half-life 36 hours), the latter representing equilibration of drug from tissue distribution sites. The prolonged phase does not contribute to drug accumulation on repeated administration but is thought to be of pharmacological significance in mediating drug effects. Renal impairment [particularly creatinine clearance < 20 ml/min (< 1.2 L/h)] results in significant accumulation of enalaprilat and necessitates dosage reduction. Accumulation is probably the cause of reduced elimination in healthy elderly individuals and in patients with concomitant diabetes, hypertension and heart failure. == References ==