The malabsorption resulting from lack of bile acid has resulted in elemental formula being suggested, which are low in fat with < 3% of calories derived from long chain triglycerides (LCT). However, reduced very long chain fatty acids (VLCFA) has not been shown to reduce blood VLCFA levels , likely because humans can endogenously produce most VLCFA. Plasma VLCFA levels are decreased when dietary VLCFA is reduced in conjunction with supplementation of Lorenzo’s oil (a 4:1 mixture of glyceryl trioleate and glyceryl trierucate) in X-ALD patients . Since docosahexaenoic acid (DHA) synthesis is impaired [59], DHA supplementation was recommended, but a placebo-controlled study has since showed no clinical efficacy . Due to the defective bile acid synthesis, fat soluble supplements of vitamins, A, D, E, and K are recommended.

Currently, no cure for Zellweger syndrome is known, nor is a course of treatment made standard. Infections should be guarded against to prevent such complications as pneumonia and respiratory distress. Other treatment is symptomatic and supportive. Patients usually do not survive beyond one year of age.

Currently, there is no cure for infantile Refsum disease syndrome, nor is there a standard course of treatment. Infections should be guarded against to prevent such complications as pneumonia and respiratory distress. Other treatment is symptomatic and supportive. Patients show variable lifespans with some individuals surviving until adulthood and into old age.

In ruminant animals, the gut fermentation of consumed plant materials liberates phytol, a constituent of chlorophyll, which is then converted to phytanic acid and stored in fats. Although humans cannot derive significant amounts of phytanic acid from the consumption of chlorophyll present in plant materials, it has been proposed that the great apes (bonobos, chimpanzees, gorillas, and orangutans) can derive significant amounts of phytanic acid from the hindgut fermentation of plant materials.

Since phytanic acid is not produced in the human body, individuals with Refsum disease are commonly placed on a phytanic acid-restricted diet and avoid the consumption of fats from ruminant animals and certain fish, such as tuna, cod, and haddock. Grass feeding animals and their milk are also avoided. Recent research has shown that CYP4 isoform enzymes could help reduce the over-accumulation of phytanic acid "in vivo". Plasmapheresis is another medical intervention used to treat patients. This involves the filtering of blood to ensure there is no accumulation of phytanic acid.

Peroxisomal disorders represent a class of medical conditions caused by defects in peroxisome functions. This may be due to defects in single enzymes important for peroxisome function or in peroxins, proteins encoded by "PEX" genes that are critical for normal peroxisome assembly and biogenesis.

Infantile Refsum disease (IRD), also called infantile phytanic acid storage disease, is a rare autosomal recessive congenital peroxisomal biogenesis disorder within the Zellweger spectrum. These are disorders of the peroxisomes that are clinically similar to Zellweger syndrome and associated with mutations in the "PEX" family of genes. IRD is associated with deficient phytanic acid catabolism, as is Adult Refsum disease, but they are different disorders that should not be confused.

Peroxisome biogenesis disorders (PBDs) include the Zellweger syndrome spectrum (PBD-ZSD) and rhizomelic chondrodysplasia punctata type 1 (RCDP1). PBD-ZSD represents a continuum of disorders including infantile Refsum disease, neonatal adrenoleukodystrophy, and Zellweger syndrome. Collectively, PBDs are autosomal recessive developmental brain disorders that also result in skeletal and craniofacial dysmorphism, liver dysfunction, progressive sensorineural hearing loss, and retinopathy.

PBD-ZSD is most commonly caused by mutations in the "PEX1", "PEX6", "PEX10", "PEX12", and "PEX26" genes. This results in the over-accumulation of very long chain fatty acids and branched chain fatty acids, such as phytanic acid. In addition, PBD-ZSD patients show deficient levels of plasmalogens, ether-phospholipids necessary for normal brain and lung function.

RCDP1 is caused by mutations in the "PEX7" gene, which encodes the PTS2 receptor. RCDP1 patients can develop large tissue stores of branched chain fatty acids, such as phytanic acid, and show reduced levels of plasmalogens.

D-Bifunctional protein deficiency (officially called 17β-hydroxysteroid dehydrogenase IV deficiency) is an autosomal recessive peroxisomal fatty acid oxidation disorder. Peroxisomal disorders are usually caused by a combination of peroxisomal assembly defects or by deficiencies of specific peroxisomal enzymes. The peroxisome is an organelle in the cell similar to the lysosome that functions to detoxify the cell. Peroxisomes contain many different enzymes, such as catalase, and their main function is to neutralize free radicals and detoxify drugs, such as alcohol. For this reason peroxisomes are ubiquitous in the liver and kidney. D-BP deficiency is the most severe peroxisomal disorder, often resembling Zellweger syndrome.

Characteristics of the disorder include neonatal hypotonia and seizures, occurring mostly within the first month of life, as well as visual and hearing impairment. Other symptoms include severe craniofacial disfiguration, psychomotor delay, and neuronal migration defects. Most onsets of the disorder begin in the gestational weeks of development and most affected individuals die within the first two years of life.

Although research is ongoing, treatment options are currently limited; vitamins are frequently prescribed, though the evidence for their effectiveness is limited.

Pyruvate has been proposed in 2007 as a treatment option. N-acetyl cysteine reverses many models of mitochondrial dysfunction.. In the case of mood disorders, specifically bipolar disorder, it is hypothesized that N-acetyl-cysteine (NAC), acetyl-L-carnitine (ALCAR), S-adenosylmethionine (SAMe), coenzyme Q10 (CoQ10), alpha-lipoic acid (ALA), creatine monohydrate (CM), and melatonin could be potential treatment options.

Neonatal adrenoleukodystrophy is an inborn error of peroxisome biogenesis. It is part of the Zellweger spectrum. It has been linked with multiple genes (at least five) associated with peroxisome biogenesis, and has an autosomal recessive pattern of inheritance.

Spindle transfer, where the nuclear DNA is transferred to another healthy egg cell leaving the defective mitochondrial DNA behind, is a potential treatment procedure that has been successfully carried out on monkeys. Using a similar pronuclear transfer technique, researchers at Newcastle University led by Douglass Turnbull successfully transplanted healthy DNA in human eggs from women with mitochondrial disease into the eggs of women donors who were unaffected. In such cases, ethical questions have been raised regarding biological motherhood, since the child receives genes and gene regulatory molecules from two different women. Using genetic engineering in attempts to produce babies free of mitochondrial disease is controversial in some circles and raises important ethical issues. A male baby was born in Mexico in 2016 from a mother with Leigh syndrome using spindle transfer.

In September 2012 a public consultation was launched in the UK to explore the ethical issues involved. Human genetic engineering was used on a small scale to allow infertile women with genetic defects in their mitochondria to have children.

In June 2013, the United Kingdom government agreed to develop legislation that would legalize the 'three-person IVF' procedure as a treatment to fix or eliminate mitochondrial diseases that are passed on from mother to child. The procedure could be offered from 29 October 2015 once regulations had been established.

Embryonic mitochondrial transplant and protofection have been proposed as a possible treatment for inherited mitochondrial disease, and allotopic expression of mitochondrial proteins as a radical treatment for mtDNA mutation load.

Currently, human clinical trials are underway at GenSight Biologics (ClinicalTrials.gov # NCT02064569) and the University of Miami (ClinicalTrials.gov # NCT02161380) to examine the safety and efficacy of mitochondrial gene therapy in Leber's hereditary optic neuropathy.

Management of rhizomelic chondrodysplasia punctate can include physical therapy, additionally orthopedic procedures improved function sometimes in affected people. However the prognosis is poor in this condition.

Malonyl-CoA decarboxylase deficiency (MCD), or Malonic aciduria is an autosomal-recessive metabolic disorder caused by a genetic mutation that disrupts the activity of Malonyl-Coa decarboxylase. This enzyme breaks down Malonyl-CoA (a fatty acid precursor and a fatty acid oxidation blocker) into Acetyl-CoA and carbon dioxide.

The signs and symptoms of this disorder typically appear in early childhood. Almost all affected children have delayed development. Additional signs and symptoms can include weak muscle tone (hypotonia), seizures, diarrhea, vomiting, and low blood sugar (hypoglycemia). A heart condition called cardiomyopathy, which weakens and enlarges the heart muscle, is another common feature of malonyl-CoA decarboxylase deficiency.

Some common symptoms in Malonyl-CoA decarboxylase deficiency, such as cardiomyopathy and metabolic acidosis, are triggered by the high concentrations of Malonyl-CoA in the cytoplasm. High level of Malonyl-CoA will inhibits β-oxidation of fatty acids through deactivating the carrier of fatty acyl group, CPT1, and thus, blocking fatty acids from going into the mitochondrial matrix for oxidation.

A research conducted in Netherlands has suggested that carnitine supplements and a low fat diet may help to reduce the level of malonic acid in our body.

Ocular albinism type 1 (OA1), also called Nettleship–Falls syndrome, is the most common type of ocular albinism, with a prevalence rate of 1:50,000. It is an inheritable classical Mendelian type X-linked recessive disorder wherein the retinal pigment epithelium lacks pigment while hair and skin appear normal. Since it is usually an X-linked disorder, it occurs mostly in males, while females are carriers unless they are homozygous. About 60 missense and nonsense mutations, insertions, and deletions have been identified in "Oa1". Mutations in OA1 have been linked to defective glycosylation and thus improper intracellular transportation.

The eponyms of the name "Nettleship–Falls syndrome" are the ophthalmologists Edward Nettleship and Harold Francis Falls.

The most common clinical observations of patients suffering from D-bifunctional protein deficiency include hypotonia, facial and skull dysmorphism, neonatal seizures, and neuronal demyelination. High levels of branched fatty acids, such as pristinic acid, bile acid intermediates, and other D-BP substrates are seen to exist. Reduced pristinic acid β-oxidation is a common indicator of D-BP deficiency. D-BP can be distinguished from Zellweger Syndrome by normal plasmalogen synthesis. Recent studies in D-BP knockout mice show compensatory upregulation of other peroxisomal enzymes in absence of D-BP such as palmitoyl-CoA oxidase, peroxisomal thiolase, and branched chain acyl-CoA oxidase.

Rhizomelic chondrodysplasia punctata is a rare, developmental brain disorder characterized by systemic shortening of the proximal bones (i.e. rhizomelia), seizures, recurrent respiratory tract infections, and congenital cataracts. The affected individuals have low levels of plasmalogens.

No cure is known for 22q11.2 deletion syndrome. Certain individual features are treatable using standard treatments. The key is to identify each of the associated features and manage each using the best available treatments.

For example, in children, it is important that the immune problems are identified early, as special precautions are required regarding blood transfusion and immunization with live vaccines. Thymus transplantation can be used to address absence of the thymus in the rare, so-called "complete" 22q11.2 deletion syndrome. Bacterial infections are treated with antibiotics. Cardiac surgery is often required for congenital heart abnormalities. Hypoparathyroidism causing hypocalcaemia often requires lifelong vitamin D and calcium supplements. Specialty clinics that provide multi-system care allow for individuals with 22q11.2 deletion syndrome to be evaluated for all of their health needs and allow for careful monitoring of the patients. An example of this type of system is the 22q Deletion Clinic at SickKids Hospital in Toronto, Canada, which provides children with 22q11 deletion syndrome ongoing support, medical care and information from a team of health care workers.

Carnitine deficiency has been extensively studied, although most commonly as a secondary finding to other metabolic conditions. The first case of SPCD was reported in the 1980s, in a child with fasting hypoketotic hypoglycemia that resolved after treatment with carnitine supplementation. Later cases were reported with cardiomyopathy and muscle weakness. Newborn screening expanded the potential phenotypes associated with SPCD, to include otherwise asymptomatic adults.

22q11.2 deletion syndrome was estimated to affect between one in 2000 and one in 4000 live births. This estimate is based on major birth defects and may be an underestimate, because some individuals with the deletion have few symptoms and may not have been formally diagnosed. It is one of the most common causes of mental retardation due to a genetic deletion syndrome.

The prevalence of 22q11.2DS has been expected to rise because of multiple reasons: (1) Thanks to surgical and medical advances, an increasing number of people are surviving heart defects associated with the syndrome. These individuals are in turn having children. The chances of a 22q11.2DS patient having an affected child is 50% for each pregnancy; (2) Parents who have affected children, but who were unaware of their own genetic conditions, are now being diagnosed as genetic testing become available; (3) Molecular genetics techniques such as FISH (fluorescence in situ hybridization) have limitations and have not been able to detect all 22q11.2 deletions. Newer technologies have been able to detect these atypical deletions.

Recently, the syndrome has been estimated to affect up to one in 2000 live births. Testing for 22q11.2DS in over 9500 pregnancies revealed a prevalence rate of 1/992.

The first suspicion of SPCD in a patient with a non-specific presentation is an extremely low plasma carnitine level. When combined with an increased concentration of carnitine in urine, the suspicion of SPCD can often be confirmed by either molecular testing or functional studies assessing the uptake of carnitine in cultured fibroblasts.

Identification of patients presymptomatically via newborn screening has allowed early intervention and treatment. Treatment for SPCD involves high dose carnitine supplementation, which must be continued for life. Individuals who are identified and treated at birth have very good outcomes, including the prevention of cardiomyopathy. Mothers who are identified after a positive newborn screen but are otherwise asymptomatic are typically offered carnitine supplementation as well. The long-term outcomes for asymptomatic adults with SPCD is not known, but the discovery of mothers with undiagnosed cardiomyopathy and SPCD has raised the possibility that identification and treatment may prevent adult onset manifestations.

The disorder can be associated with a number of psychological symptoms, anxiety, depression, social phobia, body image disorders, and patients may be subjected to discrimination, bullying and name calling especially when young. A multi-disciplinary team and parental support should include these issues.

In general, treatment for acquired partial lipodystrophy is limited to cosmetic, dietary, or medical options. Currently, no effective treatment exists to halt its progression.

Diet therapy has been shown to be of some value in the control of metabolic problems. The use of small, frequent feedings and partial substitution of medium-chain triglycerides for polyunsaturated fats appears to be beneficial.

Plastic surgery with implants of monolithic silicon rubber for correction of the deficient soft tissue of the face has been shown to be effective. False teeth may be useful in some cases for cosmetic reasons. Long-term treatment usually involves therapy for kidney and endocrine dysfunction.

Data on medications for APL are very limited. Thiazolidinediones have been used in the management of various types of lipodystrophies. They bind to peroxisome proliferator-activator receptor gamma (PPAR-gamma), which stimulates the transcription of genes responsible for growth and differentiation of adipocytes. A single report has suggested a beneficial effect from treatment with rosiglitazone on fat distribution in acquired partial lipodystrophy; however, preferential fat gain was in the lower body.

Direct drug therapy is administered according to the associated condition. Membranoproliferative glomerulonephritis and the presence of renal dysfunction largely determine the prognosis of acquired partial lipodystrophy. Standard guidelines for the management of renal disease should be followed. The course of membranoproliferative glomerulonephritis in acquired partial lipodystrophy has not been significantly altered by treatment with corticosteroids or cytotoxic medications. Recurrent bacterial infections, if severe, might be managed with prophylactic antibiotics.

The treatment of individuals with TCS may involve the intervention of professionals from multiple disciplines. The primary concerns are breathing and feeding, as a consequence of the hypoplasia of the mandibula and the obstruction of the hypopharynx by the tongue. Sometimes, they may require a tracheostomy to maintain an adequate airway, and a gastrostomy to assure an adequate caloric intake while protecting the airway. Corrective surgery of the face is performed at defined ages, depending on the developmental state.

An overview of the present guidelines:

- If a cleft palate is present, the repair normally takes place at 9–12 months old. Before surgery, a polysomnography with a palatal plate in place is needed. This may predict the postoperative situation and gives insight on the chance of the presence of sleep apnea (OSAS) after the operation.

- Hearing loss is treated by bone conduction amplification, speech therapy, and educational intervention to avoid language/speech problems. The bone-anchored hearing aid is an alternative for individuals with ear anomalies

- Zygomatic and orbital reconstruction is performed when the cranio-orbitozygomatic bone is completely developed, usually at the age of 5–7 years. In children, an autologous bone graft is mostly used. In combination with this transplantation, lipofilling can be used in the periorbital area to get an optimal result of the reconstruction. Reconstruction of the lower eyelid coloboma includes the use of a myocutaneous flap, which is elevated and in this manner closes the eyelid defect.

- External ear reconstruction is usually done when the individual is at least eight years old. Sometimes, the external auditory canal or middle ear can also be treated.

- The optimal age for the maxillomandibular reconstruction is controversial; as of 2004, this classification has been used:

1. Type I (mild) and Type IIa (moderate) 13–16 years

2. Type IIb (moderate to severe malformation) at skeletal maturity

3. Type III (severe) 6–10 years

- When the teeth are cutting, the teeth should be under supervision of an orthodontist to make sure no abnormalities occur. If abnormalities like dislocation or an overgrowth of teeth are seen, appropriate action can be undertaken as soon as possible.

- Orthognatic treatments usually take place after the age of 16 years; at this point, all teeth are in place and the jaw and dentures are mature. Whenever OSAS is detected, the level of obstruction is determined through endoscopy of the upper airways. Mandibular advancement can be an effective way to improve both breathing and æsthetics, while a chinplasty only restores the profile.

- If a nose reconstruction is necessary, it is usually performed after the orthognatic surgery and after the age of 18 years.

- The contour of the facial soft tissues generally requires correction at a later age, because of the facial skeletal maturity. The use of microsurgical methods, like the free flap transfer, has improved the correction of facial soft tissue contours. Another technique to improve the facial soft tissue contours is lipofilling. For instance, lipofilling is used to reconstruct the eyelids.