These unclassified forms are extremely rare:

- Hyperalphalipoproteinemia

- Polygenic hypercholesterolemia

Hyperlipoproteinemia type V, also known as mixed hyperlipoproteinemia familial or mixed hyperlipidemia, is very similar to type I, but with high VLDL in addition to chylomicrons.

It is also associated with glucose intolerance and hyperuricemia.

In medicine, combined hyperlipidemia (or -aemia) (also known as "multiple-type hyperlipoproteinemia") is a commonly occurring form of hypercholesterolemia (elevated cholesterol levels) characterized 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 common inherited lipid disorder, occurring in about one in 200 persons. In fact, almost one in five individuals who develop coronary heart disease before the age of 60 has this disorder.

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

Types

1. Familial combined hyperlipidemia (FCH) is the familial occurrence of this disorder, probably caused by decreased LDL receptor and increased ApoB.

2. FCH is extremely common in patients who suffer from other diseases from the metabolic syndrome ("syndrome X", incorporating diabetes mellitus type II, hypertension, central obesity and CH). Excessive free fatty acid production by various tissues leads to increased VLDL synthesis by the liver. Initially, most VLDL is converted into LDL until this mechanism is saturated, after which VLDL levels elevate.

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.

Screening among family members of people with known FH is cost-effective. Other strategies such as universal screening at the age of 16 were suggested in 2001. The latter approach may however be less cost-effective in the short term. Screening at an age lower than 16 was thought likely to lead to an unacceptably high rate of false positives.

A 2007 meta-analysis found that "the proposed strategy of screening children and parents for familial hypercholesterolaemia could have considerable impact in preventing the medical consequences of this disorder in two generations simultaneously." "The use of total cholesterol alone may best discriminate between people with and without FH between the ages of 1 to 9 years."

Screening of toddlers has been suggested, and results of a trial on 10,000 one-year-olds were published in 2016. Work was needed to find whether screening was cost-effective, and acceptable to families.

In 2016 the United States Preventive Services Task Force concluded that testing the general population under the age of 40 without symptoms is of unclear benefit.

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.

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.

Developmental delay is a potential secondary effect of chronic or recurrent hypoglycemia, but is at least theoretically preventable. Normal neuronal and muscle cells do not express glucose-6-phosphatase, so GSD I causes no other neuromuscular effects.

Neutropenia is a manifestation of this disease. Granulocyte colony-stimulating factor (G-CSF, e.g. filgrastim) therapy can reduce the risk of infection.

Familial hypercholesterolemia (FH) is a genetic disorder characterized by high cholesterol levels, specifically very high levels of low-density lipoprotein (LDL, "bad cholesterol"), in the blood and early cardiovascular disease. Since individuals with FH underlying body biochemistry is slightly different, their high cholesterol levels are less responsive to the kinds of cholesterol control methods which are usually more effective in people without FH (such as dietary modification and statin tablets). Nevertheless, treatment (including higher statin doses) is usually effective.

FH is classified as a type 2 familial dyslipidemia. There are five types of familial dyslipidemia (not including subtypes), and each are classified from both the altered lipid profile and by the genetic abnormality. For example, high LDL (often due to LDL receptor defect) is type 2. Others include defects in chylomicron metabolism, triglyceride metabolism, and metabolism of other cholesterol-containing particles, such as VLDL and IDL.

About 1 in 300 to 500 people have mutations in the "LDLR" gene that encodes the LDL receptor protein, which normally removes LDL from the circulation, or apolipoprotein B (ApoB), which is the part of LDL that binds with the receptor; mutations in other genes are rare. People who have one abnormal copy (are heterozygous) of the "LDLR" gene may develop cardiovascular disease prematurely at the age of 30 to 40. Having two abnormal copies (being "homozygous") may cause severe cardiovascular disease in childhood. Heterozygous FH is a common genetic disorder, inherited in an autosomal dominant pattern, occurring in 1:500 people in most countries; homozygous FH is much rarer, occurring in 1 in a million births.

Heterozygous FH is normally treated with statins, bile acid sequestrants, or other lipid lowering agents that lower cholesterol levels. New cases are generally offered genetic counseling. Homozygous FH often does not respond to medical therapy and may require other treatments, including LDL apheresis (removal of LDL in a method similar to dialysis) and occasionally liver transplantation.

The two forms of this lipid disorder are:

- Familial combined hyperlipidemia (FCH) is the familial occurrence of this disorder, probably caused by decreased LDL receptor and increased ApoB.

- Acquired combined hyperlipidemia is extremely common in patients who suffer from other diseases from the metabolic syndrome ("syndrome X", incorporating diabetes mellitus type II, hypertension, central obesity and CH). Excessive free fatty acid production by various tissues leads to increased VLDL synthesis by the liver. Initially, most VLDL is converted into LDL until this mechanism is saturated, after which VLDL levels elevate.

In some forms of MODY, standard treatment is appropriate, though exceptions occur:

- In MODY2, oral agents are relatively ineffective and insulin is unnecessary.

- In MODY1 and MODY3, insulin may be more effective than drugs to increase insulin sensitivity.

- Sulfonylureas are effective in the K channel forms of neonatal-onset diabetes. The mouse model of MODY diabetes suggested that the reduced clearance of sulfonylureas stands behind their therapeutic success in human MODY patients, but Urbanova et al. found that human MODY patients respond differently to the mouse model and that there was no consistent decrease in the clearance of sulfonylureas in randomly selected HNF1A-MODY and HNF4A-MODY patients.

No sexual predilection is observed because the deficiency of glycogen synthetase activity is inherited as an autosomal recessive trait.

The following characteristics suggest the possibility of a diagnosis of MODY in hyperglycemic and diabetic patients:

- Mild to moderate hyperglycemia (typically 130–250 mg/dl, or 7–14 mmol/l) discovered before 30 years of age. However, anyone under 50 can develop MODY.

- A first-degree relative with a similar degree of diabetes.

- Absence of positive antibodies or other autoimmunity (e.g., thyroiditis) in patient and family. However, Urbanova et al. found that about one quarter of Central European MODY patients are positive for islet cell autoantibodies (GADA and IA2A). Their expression is transient but highly prevalent. The autoantibodies were found in patients with delayed diabetes onset, and in times of insufficient diabetes control. The islet cell autoantibodies are absent in MODY in at least some populations (Japanese, Britons).

- Persistence of a low insulin requirement (e.g., less than 0.5 u/kg/day) past the usual "honeymoon" period.

- Absence of obesity (although overweight or obese people can get MODY) or other problems associated with type 2 diabetes or metabolic syndrome (e.g., hypertension, hyperlipidemia, polycystic ovary syndrome).

- Insulin resistance very rarely happens.

- Cystic kidney disease in patient or close relatives.

- Non-transient neonatal diabetes, or apparent type 1 diabetes with onset before six months of age.

- Liver adenoma or hepatocellular carcinoma in MODY type 3

- Renal cysts, rudimentary or bicornuate uterus, vaginal aplasia, absence of the vas deferens, epidymal cysts in MODY type 5

The diagnosis of MODY is confirmed by specific gene testing available through commercial laboratories.

Around 80 cases have been reported in the literature worldwide, hence this condition appears to be relatively rare. More than likely, sitosterolemia is significantly underdiagnosed and many patients are probably misdiagnosed with hyperlipidemia.

The overall frequency of glycogen-storage disease is approximately 1 case per 20,000–25,000 people. Glycogen-storage disease type 0 is a rare form, representing less than 1% of all cases. The identification of asymptomatic and oligosymptomatic siblings in several glycogen-storage disease type 0 families has suggested that glycogen-storage disease type 0 is underdiagnosed.

Researchers from the NIH's National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) conducted a study and found that early-onset paternal obesity is connected with an increased risk of liver disease in their kin. Researchers found that obese fathers had an elevated level of serum alanine aminotransferase (ALT), a liver enzyme, compared to fathers who were not obese. They did a secondary analysis that excluded obese offspring. Children who were a normal weight but had obese fathers still had elevated ALT levels, which indicated that a child's ALT levels are not dependent upon the child's own BMI.

Obese women have an increased risk of pregnancy-related complications, including hypertension, gestational diabetes, and blood clots. Also, the mother is at risk of going into preterm labor. Maternal obesity is also known to be associated with increased rates of complications in late pregnancy such as cesarean delivery, and shoulder dystocia. A meta-analysis estimated that Cesarean delivery rates increased with odds ratios of 1.5 among overweight, 2 among obese, and 3 among severely obese women, compared with normal weight pregnant women. In addition, morbidly obese women who have not had children before are at increased risk of all–cause preterm deliveries. It is well recognized that obese women are at increased risk of preeclampsia and that women who have never been pregnant are at higher risk of preeclampsia than women who have had children in the past.

About 25% of previously reported AGL is associated with panniculitis. Panniculitis is an inflammatory nodules of the subcutaneous fat, and in this type of AGL, adipose destruction originates locally at the infection or inflammation site and develops into generalized lipodystrophy.

Although idiopathic AGL accounts for about 50% of all AGL, it can vary in its origin and its is unclear how it develops.

No known preventive measurement has been reported.

This condition is caused by a mutation in apolipoprotein E (ApoE), that serves as a ligand for the liver receptors for chylomicrons, IDL and VLDL or Very Low Density lipoprotein receptors. The normal ApoE turns into the defective ApoE2 form due to a genetic mutation. This defect prevents the normal metabolism of chylomicrons, IDL and VLDL, otherwise known as remnants, and therefore leads to accumulation of cholesterol within scavenger cells (macrophages) to enhance development and acceleration of atherosclerosis.

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.

The disorder is treated by strictly reducing the intake of foods rich in plant sterols (e.g., vegetable oils, olives and avocados). However, dietary therapy is often never fully sufficient to control this disease since plant sterols are constituents of all plant-based foods. Statins have been used, and while these lower cholesterol levels and may ameliorate atherosclerotic disease, plant sterol levels are insufficiently lowered by their use alone.

If dietary treatment alone is insufficient, bile acid-binding resins (e.g., cholestyramine, colestipol) could be considered. In October 2002, a new cholesterol absorption inhibitor, ezetimibe, received US Food and Drug Administration (FDA) approval for use in sitosterolemia. This drug is now the standard of care, as it blocks sterol entry and can be used in combination with bile-acid resins.

Finally, ileal bypass has been performed in select cases to decrease the levels of plant sterols in the body, though this therapy was undertaken prior to the advent of ezetimibe.

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.

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.

Pediatric nonalcoholic fatty liver disease (NAFLD) was first reported in 1983. It is currently the primary form of liver disease among children. NAFLD has been associated with the metabolic syndrome, which is a cluster of risk factors that contribute to the development of cardiovascular disease and type 2 diabetes mellitus. Studies have demonstrated that abdominal obesity and insulin-resistance in particular are thought to be key contributors to the development of NAFLD. Because obesity is becoming an increasingly common problem worldwide, the prevalence of NAFLD has been increasing concurrently. Moreover, boys are more likely to be diagnosed with NAFLD than girls with a ratio of 2:1. Studies have suggested that progression toward a more advance stage of disease among children is dependent on age and presence of obesity. This finding is consistent with previous studies in adults demonstrating the same association between age and obesity, and liver fibrosis. Early diagnosis of NAFLD in children may help prevent the development of liver disease during adulthood.

This is challenging as most children with NAFLD are asymptomatic with few showing abdominal pain. Currently, liver biopsy is considered the gold standard for diagnosing NAFLD. However, this method is invasive, costly and bears greater risk for children, and noninvasive screening and diagnosing methods would have significant public health implications for children with NAFLD.

The only treatment shown to be truly effective in childhood NAFLD is weight loss.