What is Type C?

October is Niemann Pick Disease Awareness Month.

Dan had Niemann Pick Type C.  So I know more about NPC than the other types.

WARNING - THIS POST CONTAINS LOTS OF MEDICAL TERMINOLOGY

This is the most simple explanation:



Niemann-Pick disease type C (NPC) is a lipid storage disease that can present in infants, children, or adults. Neonates can present with ascites and severe liver disease from infiltration of the liver and/or respiratory failure from infiltration of the lungs. Other infants, without liver or pulmonary disease, have hypotonia and developmental delay. The classic presentation occurs in mid-to-late childhood with the insidious onset of ataxia, vertical supranuclear gaze palsy (VSGP), and dementia. Dystonia and seizures are common. Dysarthria and dysphagia eventually become disabling, making oral feeding impossible; death usually occurs in the late second or third decade from aspiration pneumonia. Adults are more likely to present with dementia or psychiatric symptoms.

NPC occurs in all ethnic groups. It is inherited as an autosomal recessive condition. This means that affected individuals have two altered copies of either NPC1 or NPC2, having inherited one copy  from each parent. Each unaffected parent (called a carrier) of an affected individual has one altered copy of the disease-causing gene and one normally-functioning copy of that gene. For a couple who are both carriers, there is a 1 in 4 chance with each pregnancy that a child will be affected by NPC, a 2 in 4 chance that the child will be a carrier of NPC, like the parents, and a 1 in 4 chance that the child will be neither a carrier nor affected.

NPC is an exceptionally variable condition. The symptoms of the disease are shared by a number of related lysosomal disorders. Further, the rate of disease progression varies from patient to  patient, even within families where more than one child is affected. This variability makes it extremely difficult to recognize and diagnose NPC, and often leads to delay in confirmation of the diagnosis.

NPC is often classified into three groups, recognizing that, in reality, there is considerable overlap and that every patient is unique:

1) Early-onset NPC (early and late infantile)
This form of the disease can begin before delivery, at delivery, or throughout the first two years of life.  Symptoms can include:
a. Abnormal build-up of fluid in the abdomen, called ascites
b. Enlarged liver and spleen
c. Severe liver disease with jaundice that can last for weeks or months
d. Respiratory failure
e. Very early death in some cases
f. Decreased muscle tone (hypotonia)
g. Developmental delay

2) Classic childhood onset NPC
This form of the disease is often first recognized at about the time a child is entering school. Signs may be subtle at first, but gradually become more noticeable, and can include:
a. Clumsiness, unsteadiness of gait, problems walking
b. Enlarged liver and/or spleen – but this may be absent or appear to resolve
c. Difficulty with voluntary upward and downward eye movements
d. Learning difficulties and worsening intellectual impairment (with eventual dementia)
e. Slurred speech and swallowing difficulties
f. Sudden loss of muscle tone, leading to falls (cataplexy)
g. Seizures
h. Sleep disturbance

3) Adult or late-onset NPC
Occurring from later adolescence into and through adulthood, this variant may include:
a. Neurologic disease as seen in childhood onset NPC
b. Major psychiatric illness (schizophrenia, depression, psychosis) with subtle, often unrecognized neurologic signs
c. Dementia


Current treatment strategies for NPC focus on management of symptoms to improve the quality of life for affected individuals and their families.These include, but are not limited to:
a. Control of seizures, cataplexy and other neurologic symptoms
b. Evaluation and treatment of sleep difficulties
c. Chest physical therapy and prevention of pneumonia
d. Physical therapy to maintain mobility
e. Swallowing and nutrition assessment; G-tube placement
f. Routine developmental and skills testing