Observational Study Conducts Long Term Follow up of Niemann-Pick Disease Type B Patients

A study published in the Orphanet Journal of Rare Diseases monitored the long-term progression of 16 patients that had Niemann-Pick Disease type B. The study served to gather important observational data on the course of this disease, which was generally found to progress slowly and has a better prognosis than some other forms of Niemann-Pick disease. The researchers also identified a new genetic variant associated with the illness.

About Niemann-Pick Disease Type B

Niemann-Pick disease type B is a metabolic disorder in which the substance sphingomyelin accumulates in the cells. It is a form of lysosomal storage disease. This type of Niemann-Pick disease is linked to mutations affecting the SMPD1 gene. It is occasionally diagnosed later in life compared to other types of Niemann-Pick. The symptoms that appear affect the organs in which sphingomyelin builds up. These symptoms include liver and spleen enlargement, appetite loss, abdominal swelling, pain, reduced platelet levels, and changes to bones.  Niemann-Pick disease type B tends to have later onset and patients are spared the neurological manifestations that appear in other types of Niemann-Pick disease. However, life-threatening complications, such as interstitial lung disease, can still develop. Treatment often includes statins to control cholesterol and blood transfusions. Organ transplant and bone marrow transplant have been used but they are not necessarily a routine part of treatment. To learn more about Niemann-Pick disease type B, click here.

About The Study

The study included 12 patients that were diagnosed in childhood and four that were diagnosed as adults. The juveniles ranged from age 1 to 14. The oldest diagnosis was at age 50. It should be noted that the study included six patients from a single family; four of them were subsequently diagnosed through family screening. When diagnosed, all patients presented with an enlarged spleen; two patients would eventually have their spleens removed because of low platelet levels. The majority of patients (88 percent) also had hepatomegaly (enlarged liver). Two patients also had symptoms of jaundice.

Some patients also presented with macular cherry red spots, an indication of accumulation of sphingomyelin in the retina. This was found in five of the patients from a single family.

Follow up varied from 6 months to 36 years, with a mean follow up of 10 years. The patients that had presented with jaundice died early in life (1.5 and 3 years of age), though their deaths were not linked to liver related complications. The study further confirmed that analysis of lysosphingomyelin (SPC) and lysosphingomyelin-509 (SPC-509) are valuable for monitoring the progression of Niemann-Pick disease type B.

The genetic variant p.G314Val was connected to the illness for the first time and appears to represent a mild and late-onset form of the disease.

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