Lysosomal Storage diseases are inherited genetic defects which result in an enzyme deficiency. The usual effect of this is to prevent the lysosome in the cells of the body from performing its natural recycling function, and various materials are inappropriately stored in the cell. In some of the diseases the enzyme may be present but there are problems with transport of the enzyme into the lysosome, but often causing a similar set of problems.

The diseases lead to a variety of progressive physical and/or mental deterioration over time. Some of the diseases may present in a "mild" form, and others with a more severe impact on the patient. Some patients survive into adulthood, but others with more severe symptoms may die in their teens or earlier.

There are currently more than 45 conditions which come within the category of Lysosomal Storage diseases. There is speculation that many other conditions may have lysosomal storage as their base cause, but the evidence of this is yet to be established for up to 50 other rare conditions.

Lysosomal diseases also exist in atypical forms which may exhibit very different symptoms from the typical form. In the typical form the enzyme will be at very low or undetectable levels, leading to the full set of symptoms, even though these symptoms may present to a mild or severe extent.

In atypical forms there may be a reduced level of enzyme that leads to reduced presentation of symptoms, but possibly significant underlying problems in apparently healthy people. There are also some forms of these diseases that appear later in life, rather than in childhood, such as Late onset Tay-Sachs.

The incidence of LSD's is about 1 in 5,000 live births and the average life expectancy across the whole group is about 15 years.

This suggests that there will be approximately 180 New Zealanders currently alive who have one of the conditions. However the level of diagnosis currently identifies only about one half of the likely number of cases. Further information about LSD's can be found at these sites:

Lysosomal Diseases Australia: this site contains a good brief overview, including information on phenotype, enzymes, therapies and prevalence. 

GOLD, the Global Organisation for Lysosomal Diseases has a brief description of the causes of lysosomal diseases and methods of inheritance, plus a database with further summary information about each of the diseases on its Education and Information page.

The Lysosomal Learning website has high quality information for patients, families and professionals, with good quality explanations, graphics and summaries of clinical features.

Taryn's World: an information site written for affected kids and their friends to help them understand genetic diseases and disabilities.