Hyperlipoproteinemia type II, by far the most common form, is further classified into types IIa and IIb, depending mainly on whether elevation in the triglyceride level occurs in addition to LDL cholesterol.

Type I hyperlipoproteinemia exists in several forms:

- Lipoprotein lipase deficiency (type Ia), due to a deficiency of lipoprotein lipase (LPL) or altered apolipoprotein C2, resulting in elevated chylomicrons, the particles that transfer fatty acids from the digestive tract to the liver

- Familial apoprotein CII deficiency (type Ib), a condition caused by a lack of lipoprotein lipase activator.

- Chylomicronemia due to circulating inhibitor of lipoprotein lipase (type Ic)

Type I hyperlipoproteinemia usually presents in childhood with eruptive xanthomata and abdominal colic. Complications include retinal vein occlusion, acute pancreatitis, steatosis, and organomegaly, and lipemia retinalis.

High cholesterol levels normally do not cause any symptoms. Yellow deposits of cholesterol-rich fat may be seen in various places on the body such as around the eyelids (known as xanthelasma palpebrarum), the outer margin of the iris (known as arcus senilis corneae), and in the tendons of the hands, elbows, knees and feet, particularly the Achilles tendon (known as a tendon xanthoma).

Accelerated deposition of cholesterol in the walls of arteries leads to atherosclerosis, the underlying cause of cardiovascular disease. The most common problem in FH is the development of coronary artery disease (atherosclerosis of the coronary arteries that supply the heart) at a much younger age than would be expected in the general population. This may lead to angina pectoris (chest pain or tightness on exertion) or heart attacks. Less commonly, arteries of the brain are affected; this may lead to transient ischemic attacks (brief episodes of weakness on one side of the body or inability to talk) or occasionally stroke. Peripheral artery occlusive disease (obstruction of the arteries of the legs) occurs mainly in people with FH who smoke; this can cause pain in the calf muscles during walking that resolves with rest (intermittent claudication) and problems due to a decreased blood supply to the feet (such as gangrene).

Atherosclerosis risk is increased further with age and in those who smoke, have diabetes, high blood pressure and a family history of cardiovascular disease.

Most people with elevated triglycerides experience no symptoms. Some forms of primary hypertriglyceridemia can lead to specific symptoms: both familial chylomicronemia and primary mixed hyperlipidemia include skin symptoms (eruptive xanthoma), eye abnormalities (lipemia retinalis), hepatosplenomegaly (enlargement of the liver and spleen), and neurological symptoms. Some experience attacks of abdominal pain that may be mild episodes of pancreatitis. Eruptive xanthomas are 2–5 mm papules, often with a red ring around them, that occur in clusters on the skin of the trunk, buttocks and extremities. Familial dysbetalipoproteinemia causes larger, tuberous xanthomas; these are red or orange and occur on the elbows and knees. Palmar crease xanthomas may also occur.

The diagnosis is made on blood tests, often performed as part of screening. Once diagnosed, other blood tests are usually required to determine whether the raised triglyceride level is caused by other underlying disorders ("secondary hypertriglyceridemia") or whether no such underlying cause exists ("primary hypertriglyceridaemia"). There is a hereditary predisposition to both primary and secondary hypertriglyceridemia.

Acute pancreatitis occurs in people whose triglyceride levels are above 1000 mg/dl (11.3 mmol/l). Hypertriglyceridemia is associated with 1–4% of all cases of pancreatitis. The symptoms are similar to pancreatitis secondary to other causes, although the presence of xanthomas or risk factors for hypertriglyceridemia may offer clues.

Combined hyperlipidemia (or -aemia) (also known as multiple-type hyperlipoproteinemia) is a commonly occurring form of hypercholesterolemia (elevated cholesterol levels) characterised by increased LDL and triglyceride concentrations, often accompanied by decreased HDL. On lipoprotein electrophoresis (a test now rarely performed) it shows as a hyperlipoproteinemia type IIB. It is the most commonly inherited lipid disorder, occurring in around one in 200 persons. In fact, almost one in five individuals who develop coronary heart disease before the age of 60 have this disorder.

The elevated triglyceride levels (>5 mmol/l) are generally due to an increase in very low density lipoprotein (VLDL), a class of lipoproteins prone to cause atherosclerosis.

Hypertriglyceridemia denotes high ("hyper-") blood levels ("-emia") of triglycerides, the most abundant fatty molecule in most organisms. Elevated levels of triglycerides are associated with atherosclerosis, even in the absence of hypercholesterolemia (high cholesterol levels), and predispose to cardiovascular disease. Very high triglyceride levels also increase the risk of acute pancreatitis. Hypertriglyceridemia itself is usually symptomless, although high levels may be associated with skin lesions known as "xanthomas".

The diagnosis is made on blood tests, often performed as part of screening. Once diagnosed, other blood tests are usually required to determine whether the raised triglyceride level is caused by other underlying disorders ("secondary hypertriglyceridemia") or whether no such underlying cause exists ("primary hypertriglyceridaemia"). There is a hereditary predisposition to both primary and secondary hypertriglyceridemia.

Weight loss and dietary modification may improve hypertriglyceridemia. The decision to treat hypertriglyceridemia with medication depends on the levels and on the presence of other risk factors for cardiovascular disease. Very high levels that would increase the risk of pancreatitis is treated with a drug from the fibrate class. Niacin and omega-3 fatty acids as well as drugs from the statin class may be used in conjunction, with statins being the main drug treatment for moderate hypertriglyceridemia where reduction of cardiovascular risk is required.

"Laboratory changes": massive accumulation of chylomicrons in the plasma and corresponding severe hypertriglyceridemia. Typically, the plasma in a fasting blood sample appears creamy (plasma lactescence).

"Clinical symptoms:" The disease often presents in infancy with colicky pain, failure to thrive, and other symptoms and signs of the chylomicronemia syndrome. In women the use of estrogens or first pregnancy are also well known trigger factors for initial manifestation of LPLD. At all ages, the most common clinical manifestation is recurrent abdominal pain and acute pancreatitis. The pain may be epigastric, with radiation to the back, or it may be diffuse, with the appearance of an emergent acute abdomen. Other typical symptoms are eruptive xanthomas (in about 50% of patients), lipemia retinalis and hepatosplenomegaly.

"Complications:" Patients with LPLD are at high risk of acute pancreatitis, which can be life-threatening, and can lead to chronic pancreatic insufficiency and diabetes.

Both conditions are treated with fibrate drugs, which act on the peroxisome proliferator-activated receptors (PPARs), specifically PPARα, to decrease free fatty acid production. Statin drugs, especially the synthetic statins (atorvastatin and rosuvastatin), can decrease LDL levels by increasing hepatic reuptake of LDL due to increased LDL-receptor expression.

Lipoprotein lipase deficiency (also known as "familial chylomicronemia syndrome", "chylomicronemia", "chylomicronemia syndrome" and "hyperlipoproteinemia type Ia") is a rare autosomal recessive lipid disorder caused by a mutation in the gene which codes lipoprotein lipase. As a result, afflicted individuals lack the ability to produce lipoprotein lipase enzymes necessary for effective breakdown of triglycerides.

Although hypercholesterolemia itself is asymptomatic, longstanding elevation of serum cholesterol can lead to atherosclerosis (hardening of arteries). Over a period of decades, elevated serum cholesterol contributes to formation of atheromatous plaques in the arteries. This can lead to progressive narrowing of the involved arteries. Alternatively smaller plaques may rupture and cause a clot to form and obstruct blood flow. A sudden blockage of a coronary artery may result in a heart attack. A blockage of an artery supplying the brain can cause a stroke. If the development of the stenosis or occlusion is gradual, blood supply to the tissues and organs slowly diminishes until organ function becomes impaired. At this point tissue ischemia (restriction in blood supply) may manifest as specific symptoms. For example, temporary ischemia of the brain (commonly referred to as a transient ischemic attack) may manifest as temporary loss of vision, dizziness and impairment of balance, difficulty speaking, weakness or numbness or tingling, usually on one side of the body. Insufficient blood supply to the heart may cause chest pain, and ischemia of the eye may manifest as transient visual loss in one eye. Insufficient blood supply to the legs may manifest as calf pain when walking, while in the intestines it may present as abdominal pain after eating a meal.

Some types of hypercholesterolemia lead to specific physical findings. For example, familial hypercholesterolemia (Type IIa hyperlipoproteinemia) may be associated with xanthelasma palpebrarum (yellowish patches underneath the skin around the eyelids), arcus senilis (white or gray discoloration of the peripheral cornea), and xanthomata (deposition of yellowish cholesterol-rich material) of the tendons, especially of the fingers. Type III hyperlipidemia may be associated with xanthomata of the palms, knees and elbows.

Sitosterolemia may share several clinical characteristics with the well-characterized familial hypercholesterolemia (FH), such as the development of tendon xanthomas in the first 10 years of life and the development of premature atherosclerosis . However, in contrast to FH patients, sitosterolemia patients usually have normal to moderately elevated total sterol levels and very high levels of plant sterols (sitosterol, campesterol, stigmasterol, avenosterol) and 5α-saturated stanols in their plasma. Plasma sitosterol levels in sitosterolemia patients are 10–25 times higher than in normal individuals (8–60 mg/dl). Not all patients with sitosterolemia have tendon xanthomas, thus absence of this should not be used to exclude this diagnosis.

Xanthomas may appear at any age, even in childhood. These may be present as subcutaneous xanthomas on the buttocks in children or in usual locations (e.g., Achilles tendon, extensor tendons of the hand) in children and adults. Xanthelasma and corneal arcus are less common. Decreased range of motion with possible redness, swelling, and warmth of joints due to arthritis may be present.In addition, sitosterolemia patients may develop hemolytic episodes and splenomegaly.

Untreated, the condition causes a significant increase in morbidity and mortality. Coronary heart disease and its inherent health consequences are the primary causes of illness and premature death in untreated patients.

This condition is suspected to result in liver dysfunction and cirrhosis, in the context of sitosterolemia, is reported

Signs of familial dysbetaproteinemia include xanthoma striatum palmare (orange or yellow discoloration of the palms) and tuberoeruptive xanthomas over the elbows and knees. The disease leads to premature atherosclerosis and therefore a possible early onset of coronary artery disease and peripheral vascular disease leading to a heart attack, i.e. myocardial infarction, chest pain on exercise, i.e. angina pectoris or stroke in young adults or middle aged patients.

Hypercholesterolemia, also called high cholesterol, is the presence of high levels of cholesterol in the blood. It is a form of high blood lipids and hyperlipoproteinemia (elevated levels of lipoproteins in the blood).

Elevated levels of non-HDL cholesterol and LDL in the blood may be a consequence of diet, obesity, inherited (genetic) diseases (such as LDL receptor mutations in familial hypercholesterolemia), or the presence of other diseases such as diabetes and an underactive thyroid.

Cholesterol is one of three major classes of lipids which all animal cells use to construct their membranes and is thus manufactured by all animal cells. Plant cells do not manufacture cholesterol. It is also the precursor of the steroid hormones and bile acids. Since cholesterol is insoluble in water, it is transported in the blood plasma within protein particles (lipoproteins). Lipoproteins are classified by their density: very low density lipoprotein (VLDL), low density lipoprotein (LDL), intermediate density lipoprotein (IDL) and high density lipoprotein (HDL). All the lipoproteins carry cholesterol, but elevated levels of the lipoproteins other than HDL (termed non-HDL cholesterol), particularly LDL-cholesterol, are associated with an increased risk of atherosclerosis and coronary heart disease. In contrast, higher levels of HDL cholesterol are protective.

Avoiding trans fats and replacing saturated fats in adult diets with polyunsaturated fats are recommended dietary measures to reduce total blood cholesterol and LDL in adults. In people with very high cholesterol (e.g. familial hypercholesterolemia), diet is often not sufficient to achieve the desired lowering of LDL, and lipid-lowering medications are usually required. If necessary, other treatments such as LDL apheresis or even surgery (for particularly severe subtypes of familial hypercholesterolemia) are performed. About 34 million adults in the United States have high blood cholesterol.

The clinical presentation is similar to people with congenital lipodystrophy: the only difference is that AGL patients are born with normal fat distribution and symptoms develop in childhood and adolescence years and rarely begins after 30 years of age. Females are more often affected than males, with ratio being 3:1.

The hallmark characteristics are widespread loss of subcutaneous fat, ectopic fat deposition, leptin deficiency, and severe metabolic abnormalities such as insulin resistance. Subcutaneous fat loss in AGL patients are visible in all parts of the body. AGL mostly affects face and the extremities and may look sunken or swollen in the eyes. However, the degree and location of severity may vary by person. Especially, intra-abdominal fat loss is variable. As subcutaneous fat is lost, affected areas show prominent structures of veins and muscle. Those with panniculitis-associated AGL may present erythematous nodules.

Metabolic complications include insulin resistance, high metabolic rate, and uncontrolled lipid levels such as hypertriglyceridemia, low HDL, and high LDL. Patients may develop diabetes mellitus secondary to insulin resistance.

Recent case reports reveled that lymphoma is present in some patients but its prevalence is not known at this time.

Familial dysbetalipoproteinemia or type III hyperlipoproteinemia (also known as remnant hyperlipidemia, "remnant hyperlipoproteinaemia", "broad beta disease" and "remnant removal disease") is a condition characterized by increased total cholesterol and triglyceride levels, and decreased HDL levels.

Acquired generalized lipodystrophy (also known as "Lawrence syndrome," and "Lawrence–Seip syndrome", abbreviation: AGL) is a rare skin condition that appears during childhood or adolescence, characterized by fat loss affecting large areas of the body, particularly the face, arms, and legs. There are 4 types of lipodystrophy based on its onset and areas affected: acquired or inherited (congenital or familial), and generalized or partial. Both acquired or inherited lipodystrophy present as loss of adipose tissues. The near-total loss of subcutaneous adipose tissue is termed generalized lipodystrophy while the selective loss of adipose tissues is denoted as partial lipodystrophy. Thus, as the name suggests, AGL is a near-total deficiency of adipose tissues in the body that is developed later in life. It is an extremely rare disease that only about 100 cases are reported worldwide. There are three main etiologies of AGL suspected: autoimmune, panniculitis-associated, or idiopathic. After its onset, the disease progresses over a few days, weeks, months, or even in years. Clinical presentations of AGL are similar to other lipodystrophies, including metabolic complications and hypoleptinemia. Treatments are also similar and mainly supportive for symptomatic alleviation. Although HIV- or drug-induced lipodystrophy are a type of acquired lipodystrophy, its origin is very specific and distinct hence is usually not discussed with AGL (see HIV-Associated Lipodystrophy).

Apolipoprotein B deficiency (also known as "Familial defective apolipoprotein B-100") is an autosomal dominant disorder resulting from a missense mutation which reduces the affinity of apoB-100 for the low-density lipoprotein receptor (LDL Receptor) . This causes impairments in LDL catabolism, resulting in increased levels of low-density lipoprotein in the blood. The clinical manifestations are similar to diseases produced by mutations of the LDL receptor, such as familial hypercholesterolemia. Treatment may include, niacin or statin or ezetimibe.

It is also known as "normotriglyceridemic hypobetalipoproteinemia".

Tangier disease (also known as Familial alpha-lipoprotein deficiency) or hypoalphalipoproteinemia is a rare inherited disorder characterized by a severe reduction in the amount of high density lipoprotein (HDL), often referred to as "good cholesterol", in the bloodstream.

Sitosterolemia (also known as "Phytosterolemia") is a rare autosomal recessively inherited lipid metabolic disorder. It is characterized by hyperabsorption and decreased biliary excretion of dietary sterols (including the plant phytosterol beta-sitosterol). Healthy persons absorb only about 5% of dietary plant sterols, but sitosterolemia patients absorb 15% to 60% of ingested sitosterol without excreting much into the bile. The phytosterol campesterol is more readily absorbed than sitosterol.

Sitosterolemia patients develop hypercholesterolemia, tendon and tuberous xanthomas, premature development of atherosclerosis, and abnormal hematologic and liver function test results.

Symptoms of the familial form include visual impairment caused by diffuse corneal opacities, target cell hemolytic anemia, and renal failure. Less common symptoms include atherosclerosis, hepatomegaly (enlarged liver), splenomegaly (enlarged spleen), and lymphadenopathy.

Fish-eye disease is less severe and most commonly presents with impaired vision due to corneal opacification. It rarely presents with other findings, although, atherosclerosis, hepatomegaly, splenomegaly, and lymphadenopathy can occur. Carlson and Philipson found that the disease was named so because the cornea of the eye was so opaque or cloudy with dots of cholesterol that it resembled a boiled fish.

If an individual only carry one copy of the mutated gene, they typically do not show symptoms.

Patients generally have a benign course, and typically present with hepatomegaly and growth retardation early in childhood. Mild hypoglycemia, hyperlipidemia, and hyperketosis may occur. Lactic acid and uric acid levels may be normal. However, lactic acidosis may occur during fasting.

Individuals that are homozygotes for Tangier's disease develop various cholesterol ester depositions. These are especially visible in the tonsils, as they may appear yellow/orange. The cholesterol esters may also be found in lymph nodes, bone marrow, the liver and spleen.

Due to the cholesterol ester depositions the tonsils may be enlarged. Hepatosplenomegaly (enlarged liver and spleen) is common.

Neuropathy and cardiovascular disease are the most devastating developments caused by Tangier's disease.

Palmar xanthoma is clinically characterized by yellowish plaques that involve the palms and flexural surfaces of the fingers. Plane xanthomas are characterised by yellowish to orange, flat macules or slightly elevated plaques, often with a central white area which may be localised or generalised. They often arise in the skin folds, especially the palmar creases. They occur in hyperlipoproteinaemia type III and type IIA, and in association with biliary cirrhosis. The presence of palmar xanthomata, like the presence of tendinous xanthomata, is indicative of hypercholesterolaemia.

A xanthelasma is a sharply demarcated yellowish collection of cholesterol underneath the skin, usually on or around the eyelids. Strictly, a xanthelasma is a distinct condition, only being called a xanthoma when becoming larger and nodular, assuming tumorous proportions. Still, it is often classified simply as a subtype of xanthoma.