Von Hippel-Lindau disease. Sanfilippo syndrome. Epispadias complex. If you haven’t heard of these conditions, you’re not alone. And that is why each year, the last day of February marks National Rare Disease Day — an international effort to raise awareness among the general public and decision-makers about obscure conditions and the impact they have on the lives of their sufferers.
To begin with, the term "rare" means different things in different places. In Europe, a disease is classified as such when it affects 1 in 2,000 individuals, whereas in the United States rare in when fewer than 200,000 people are afflicted at any given time. There are approximately 6,000 known rare diseases — roughly 80 percent of which have genetic origins — while the remaining are a result of infections, allergies or have environmental roots.
Signs and symptoms of rare diseases are varied, complex and differ depending on the individual. This makes it difficult to generalize or discuss them as a whole in any way that makes sense. So in recognition of Rare Disease Day, we thought we’d shed some light on a few of the least common of the rare diseases that affect both children and adults across the U.S. and abroad.
Prader Willi Syndrome
PWS is characterized by a combination of cognitive impairment, behavioral problems and insatiable hunger in adolescents that, if left untreated, can lead to childhood life-threatening obesity. Serious problems can develop as a result of hyperphagia including sleep apnea, diabetes and cardiac insufficiency among others. Affected individuals also suffer from a growth hormone deficiency and therefore may exhibit a markedly shorter stature and proportionately greater body mass for their sex and age. PWS is caused by defective genetic imprinting, and it affects an estimated 1 in 10,000-30,000 individuals. Currently, there is no cure for Prader Willi Syndrome.
Pulmonary Arterial Hypertension
PAH is a progressive condition that affects the heart and lungs. Unlike traditional hypertension, PAH is specific to the named artery — the blood vessel that carries deoxygenated blood from the heart to the lungs. Signs and symptoms of PAH include lower extremity edema (swelling), dyspnea (shortness of breath) even at very low levels of exertion and syncope (fainting) because of the weakening of the right ventricle. Causes of PAH can be either genetic or idiopathic with an estimated 15-50 cases per million diagnosed with the condition, which can be life threatening if left untreated.
Maple Syrup Urine Disease
This disease is a disorder in which the body cannot break down certain proteins leucine, isoleucine and valine — otherwise known as the branched chain amino acids. Because the body is unable to metabolize these proteins properly, lethal levels accumulate in the blood. Common signs and symptoms include: lethargy, seizures, vomiting and urine that smells “sweet” like maple syrup. If undetected, MSUD can result in brain damage or mental disability. Currently, there is no cure for it, but the condition can be managed through a low protein diet while fluids, fats and sugars are sometimes administered though an IV to keep the blood from becoming over-saturated with amino acids. Maple syrup urine disease is a genetic disorder and the estimated prevalence is about 1 in every 150,000.
This is just a snapshot of the thousands of rare disorders that currently exist. But since it's inception back in 2008, Rare Disease Day has served as a vehicle to enhance awareness and education about the myriad of conditions that hundreds of thousands of individuals continue to suffer from.