Niemann-Pick Disease Type B (or otherwise known as “acid sphingomyelinase-deficient Niemann-Pick disease” (ASM-deficient NPD) or “ASM deficiency”)* is a chronic inherited condition involving lipid metabolism. The body cannot properly metabolize a fatty lipid called sphingomyelin due to a deficient enzyme called acid sphingomyelinase which is functioning at approximately 1% to 10% of normal. As a result of the enzyme deficiency, sphingomyelin builds up in the body, causing cell death and making it harder for certain organs to work properly. People with this condition experience a buildup of lipids in the spleen, liver, and lungs. Signs and symptoms may include enlarged liver and spleen, growth retardation, and problems with lung function including frequent lung infections. Other signs include blood abnormalities such as elevated levels of cholesterol and other lipids (fats), and decreased numbers of blood cells involved in clotting. Type B is typically non-neurological; however, a small percentage of patients may have neurological involvement (these patients are sometimes referred to as Type A/B or intermediate patients). The severity of Type B varies greatly from case to case, sibling to sibling, and acid sphingomyelinase activity does not appear to correlate with severity.
People with Type B may survive into adulthood, however, lifespan will likely be affected and during one study there was a pediatric mortality rate of 19%. Pediatric causes of death during the study included pneumonia, liver failure and hemorrhage, and occurred between ages 12-18.
For Type B patients, enzyme replacement therapy by recombinant acid sphingomyelinase is not yet available, but a phase 2 clinical trial is under development. Results of clinical trial 1B are available [click here].
Niemann-Pick disease type A is genetically similar to Type B; however, it is neurological due to sphingomyelin buildup in the brain along with the spleen, liver and lungs. The prognosis for Type A is very poor. It causes mental disability, loss of motor skills, and enlargement of the liver and spleen, among other symptoms. The disease is often fatal by the age of 4. Symptoms of Niemann-Pick disease type A usually begin within the first few months of life.
* Niemann Pick Type C located on chromosome 18 (Type A and B are on chromosome 11) is a distinct different disorder than Niemann Pick Type A and B; however, it has been able to become establish under the Niemann Pick name. So often Niemann Pick Type A, B and intermediate forms have coined the collective term of “acid sphingomyelinase-deficient Niemann-Pick disease” (ASM-deficient NPD) or “ASM deficiency”.
How Common is Niemann Pick Type B?
Accurate estimates for Type B are unavailable; however, according to one estimate, Niemann-Pick disease type B affects approximately 1,000 individuals worldwide (higher-end estimates have it at 3,000). Incidence for Type B is significantly less than Type A (some estimates have it at 85% less; however, some estimates state Type A significantly less than Type B) and pan-ethnic with more prevalent occurrences among descendants of North African, Turkish, and Arabic descent. The prevalence in Ashkenazi Jews is much lower than in Type A.
Type A generally occurs among Ashkenazi Jews. Carrier frequency in Ashkenazi Jews is 1:90 suggesting disease frequency of 1:40,000. For non-Ashkenazi Jews the frequency is 1:250,000.
A 2002 study identified Type B patients in 29 countries with the most common ethnic group being Turkish, followed by Arabic and Scottish. Frequency of Type B is most likely higher than quoted literature because diagnosis is often challenging. This is due to lack of knowledge among physicians, lack of enzyme testing, variable symptoms, and misdiagnosis. It is not uncommon for patients to receive a misdiagnosis or to receive the Type B diagnosis a few years after first signs of symptoms.
How is it inherited?
Type A and B are the result of mutation of the SMPD1 gene located on chromosome 11. Both parents have to be carriers of the mutated gene to pass along to their offspring. In each pregnancy of a couple that each carry the mutated gene, there is a 25% chance that they will pass on this gene mutation to their child.
When both parents are carriers, there is,
25% chance that the child will have the disease
50% chance that the child will be a carrier
25% chance that the child will not be a carrier and will not have the disease.
When one parent is a carrier, there is,
25% chance that the child will be a carrier
25% chance that the child will not have the disease and will not be a carrier
Is there a psychological impact?
A 2006 study (Henderson, 2006) suggests that individuals suffering from Type B face numerous social and psychological hurdles.
Five major findings emerged:
(1) limited physical activity, social isolation, and peer rejection were identified as significant stressors;
(2) stressors had a specific impact during the age span of 10-16 years;
(3) parents and adult patients expressed frustration regarding the lack of available information and treatment;
(4) patients described close family relationships as a way of coping with illness as a result of social isolation; and
(5) adult patients identified early medical experiences as having a considerable psychological impact.
Additionally, there is a discrepancy in how parents vs. adolescence felt about the disease. Generally stunted/delayed growth as well as an enlarged stomach lowered self-esteem and were targets of teasing. Further the avoidance of contact sports and other activities due to enlarged spleen and other health matters made adolescents feel isolated from society.
How do you treat your daughter?
We eat as healthy as we can (organic fruits and vegetables, whole grains and lean meats). However, Niemann Pick Type B patients have increased caloric requirements because they have higher-than-normal metabolism. The metabolic rate may be 20% to 30% higher than the average population, but despite the need for more food, patients with pronounced liver and/or spleen enlargement typically have a suppressed appetite. So we typically allow our daughter to take breaks when she is full and provide plenty of healthy snacks throughout the day.
We try to eat healthy and at the same time meet her caloric requirement. We originally overhauled her entire diet but realizing the restrictions were reducing her caloric intake we loosened and modified her diet. Additionally, we have educated her on what is healthy and pushed the pendulum to the healthier foods. The only change we have maintained is no red meat, no juices (more water) and reduced milk intake (replaced with almond milk). Additionally, there appears to be a high intolerance in the community to wheat. We have slightly reduced her wheat intake and eat buckwheat as a substitute as possible.
Additionally, we provide her vitamin supplements. Typically, Niemann Pick Type B patients have numerous nutritional deficiencies including vitamin B-12, calcium/vitamin D, and iron, among other nutritional issues.
We provide our daughter with a cocktail of the following vitamins:
(2) Multi-vitamin (high in B-12)
(3) Fish oil (our multi-vitamin includes fish oil)
(4) Calcium Chocolate Wafer (high in vitamin D, Vitamin K, and Magnesium)
(5) Milk thistle (for liver health)
We believe diet is important in overall health and possibly slowing down any progressive ailments.
Further we do not reduce her activities (except gymnastics). She plays on the playground with the other kids, dances, and swims without restrictions.
NIEMANN PICK TYPE B
Studies / Publications
of 3 cases 
Niemann-Pick Disease Type B 
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