Niemann Pick Disease have first defined by German Doctor Albert Niemann in year 1914. Then Doctor Albert Pick have describe the Type B form of this disease in year 1927. Therefore, the disease have called Niemann Pick Disease. It has reported about of 1 in 100.000 births. This disease is also a lipid depot disease due to deficiency of sphingomyelinase activity. In these disease, cholesterol may accumulate in different tissues and vital organs such as liver, spleen, heart and brain. Sometimes swellings can observed due to excessive accumulation of cholesterol.
This disease have an autosomal recessive inheritance. Unless the mother and father are not carriers or diseased, the disease will not seen in children and can not affect another individual. Because of autosomal recessive inheritance is more common in those with consanguineous marriages. The genetic defect is on NPS1 gene that have defined in 11 and 12’th loci in the short arm of 18’th chromosome. This genertic defect have reported about %95 of these patient. In the other hand, %5 genetic defect is on NPC2 gene that is localised on 14’th chromosome.
Type A form is the infantile type and it have a faster progression. Hepatosplenomegaly is detected in the first months of life. Infants who have Type A disease will usually die between the ages of 2 to 3 years. Approximately %50 of these patients have cherry red macular spot on the eye examination. The genetic defect is usually on 11’th chromosome.
These patients will have splenomegaly too, but usually can not detected during infancy. It will detect usually in puberty period.
This is the most rare type of this disease. Psychosis and dementia are evident and usually this type patients will die on the 2nd decade.
For diagnosis, careful bone marrow biopsy and examination should performed. Lipid-laden macrophages (foam cells) will seen in this examination.
Acid sphingomyelinase activity measurement in peripheral cells may diagnose this disease also. The activity of this enzyme is measured by using numeraus radioactivity, fluorescent and colorimetric substrate.
Demonstration of genetic defect by PCR is another definitive diagnostic method.
If the symptoms begins in infancy period the patient will usually die before 5 age of live. With it, if the symptoms begins after 5 years of age, the patient may live up to 20 of age. Death is usually due to lung infection and aspiration between 10 to 20 years of age. The most rare type is C type and this patients lifespan is between 20 to 30 of age.
Mutated genes can detected from chorionic villus cells or amniocytes by RT-PCR and Single-strand conformation polymorphism (SSCP) methods. Chorionic villus biopsy is a procedure that performed in the same way as amniocentesis in ultrasonography. This procedure may performed between 11 and 14 weeks of pregnancy.