Infant mortality is high for patients diagnosed with early onset; mortality can occur within less than 2 months, while children diagnosed with late-onset syndrome seem to have higher rates of survival. Patients suffering from a complete lesion of mut0 have not only the poorest outcome of those suffering from methylaonyl-CoA mutase deficiency, but also of all individuals suffering from any form of methylmalonic acidemia.

The signs and symptoms of holocarboxylase synthetase deficiency typically appear within the first few months of life, but the age of onset varies. Affected infants often have immunodeficiency diseases, difficulty feeding, breathing problems, a skin rash, hair loss (alopecia), and a lack of energy (lethargy). Immediate treatment and lifelong management (using biotin supplements) may prevent many of these complications. If left untreated, the disorder can lead to delayed development, seizures, and coma. These medical problems may be life-threatening in some cases.

Since biotin is in many foods at low concentrations, deficiency is rare except in locations where malnourishment is very common. Pregnancy, however, alters biotin catabolism and despite a regular biotin intake, half of the pregnant women in the U.S. are marginally biotin deficient.

Mutations in the "HLCS" gene cause holocarboxylase synthetase deficiency. The "HLCS" gene makes an enzyme, holocarboxylase synthetase, that attaches biotin to other molecules. Biotin, a B vitamin, is found in foods such as liver, egg yolks, and milk. It is essential for the normal production and breakdown of proteins, fats, and carbohydrates in the body. Mutations in the "HLCS" gene reduce the activity of holocarboxylase synthetase, preventing cells from using biotin effectively and disrupting many cellular functions.

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered.

Symptoms can be reduced through avoidance of leucine, an amino acid. Leucine is a component of most protein-rich foods; therefore, a low-protein diet is recommended. Some isolated cases of this disorder have responded to supplemental biotin; this is not altogether surprising, consider that other biotin-related genetic disorders (such as biotinidase deficiency and holocarboxylase synthetase deficiency) can be treated solely with biotin. Individuals with these multiple carboxylase disorders have the same problem with leucine catabolism as those with 3-methylcrotonyl-CoA carboxylase deficiency.

It is one of the 29 conditions currently recommended for newborn screening by the American College of Medical Genetics.

Multiple carboxylase deficiency is a form of metabolic disorder involving failures of carboxylation enzymes.

The deficiency can be in biotinidase or holocarboxylase synthetase.

These conditions respond to biotin.

Forms include:

- Holocarboxylase synthetase deficiency - neonatal;

- Biotinidase deficiency - late onset;

If left untreated, the symptoms can include feeding problems, decreased body tone, generalized red rash with skin exfoliation and baldness, failure to thrive, seizure, coma, developmental delay, foul smelling urine, lactic acidosis, and high levels of ketones and ammonia in the blood.

Glutathione synthetase deficiency is a rare autosomal recessive metabolic disorder that prevents the production of glutathione. Glutathione helps prevent damage to cells by neutralizing harmful molecules generated during energy production. Glutathione also plays a role in processing medications and cancer-causing compounds (carcinogens), and building DNA, proteins, and other important cellular components.

In the United States, biotin supplements are readily available without a prescription in amounts ranging from 1,000 to 10,000 micrograms (30 micrograms is identified as Adequate Intake).

Citrullinemia type I (CTLN1), also known as arginosuccinate synthetase deficiency, is a rare disease caused by a deficiency in argininosuccinate synthetase, an enzyme involved in excreting excess nitrogen from the body. There are mild and severe forms of the disease, which is one of the urea cycle disorders.

People with methylmalonyl CoA mutase deficiency exhibit many symptoms similar to other diseases involving inborn errors of metabolism. Sometimes the symptoms appear shortly after birth, but other times the onset of symptoms is later.

Newborn babies experience with vomiting, acidosis, hyperammonemia, hepatomegaly (enlarged livers), hyperglycinemia (high glycine levels), and hypoglycemia (low blood sugar). Later, cases of thrombocytopenia and neutropenia can occur.

In some cases intellectual and developmental disabilities, such as autism, were noted with increased frequency in populations with methylmalonyl-CoA mutase deficiency.

ASS1 is the gene mutated in citrullinemia type I. Mutations in this gene have an autosomal recessive mode of inheritance.

Glutathione synthetase deficiency can be classified into three types: mild, moderate and severe.

- "Mild" glutathione synthetase deficiency usually results in the destruction of red blood cells (hemolytic anemia). Rarely, affected people also excrete large amounts of a compound called 5-oxoproline (also called pyroglutamic acid, or pyroglutamate) in their urine (5-oxoprolinuria). This compound builds up when glutathione is not processed correctly in cells.

- Individuals with "moderate" glutathione synthetase deficiency may experience symptoms beginning shortly after birth including hemolytic anemia, 5-oxoprolinuria, and elevated acidity in the blood and tissues (metabolic acidosis).

- In addition to the features present in moderate glutathione synthetase deficiency, individuals affected by the "severe" form of this disorder may experience neurological symptoms. These problems may include seizures; a generalized slowing down of physical reactions, movements, and speech (psychomotor retardation); intellectual disability; and a loss of coordination (ataxia). Some people with severe glutathione synthetase deficiency also develop recurrent bacterial infections.[citation missing]

N-Acetylglutamate synthase (or synthetase) deficiency is an autosomal recessive urea cycle disorder.

Although there is currently no cure, treatment includes injections of structurally similar compound, N-Carbamoyl-L-glutamate, an analogue of N-Acetyl Glutamate. This analogue likewise activates CPS1. This treatment mitigates the intensity of the disorder.

If symptoms are detected early enough and the patient is injected with this compound, levels of severe mental retardation can be slightly lessened, but brain damage is irreversible.

Early symptoms include lethargy, vomiting, and deep coma.

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

Carbamoyl phosphate synthetase I deficiency (CPS I deficiency) is an autosomal recessive metabolic disorder that causes ammonia to accumulate in the blood due to a lack of the enzyme carbamoyl phosphate synthetase I. Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The nervous system is especially sensitive to the effects of excess ammonia.

CPS I deficiency is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder.

The major morbidity is a risk of fasting hypoglycemia, which can vary in severity and frequency. Major long-term concerns include growth delay, osteopenia, and neurologic damage resulting in developmental delay, intellectual deficits, and personality changes.

While inherited deficiencies in uroporphyrinogen decarboxylase often lead to the development of PCT, there are a number of risk factors that can both cause and exacerbate the symptoms of this disease. One of the most common risk factors observed is infection with the Hepatitis C virus. One review of a collection of PCT studies noted Hepatitis C infection in 50% of documented cases of PCT. Additional risk factors include alcohol abuse, excess iron (from iron supplements as well as cooking on cast iron skillets), and exposure to chlorinated cyclic hydrocarbons and Agent Orange.

It can be a paraneoplastic phenomenon.

Porphyria cutanea tarda has a prevalence estimated at approximately 1 in 10,000. An estimated 80% of porphyria cutanea tarda cases are sporadic. The exact frequency is not clear because many people with the condition never experience symptoms and those that do are often misdiagnosed with anything ranging from idiopathic photodermatitis and seasonal allergies to hives.

Citrullinemia is an autosomal recessive urea cycle disorder that causes ammonia and other toxic substances to accumulate in the blood. Since the substances also accumulate in the urine, the disorder can also be called citrullinuria.

Two forms of citrullinemia have been described, both having different signs and symptoms, and are caused by mutations in different genes. Citrullinemia belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of chemical reactions taking place in the liver. These reactions process excess nitrogen, generated when protein is used for energy by the body, to make urea, which is excreted by the kidneys.

Children with DOCK8 deficiency do not tend to live long; sepsis is a common cause of death at a young age. CNS and vascular complications are other common causes of death.

The prevalence of vitamin K deficiency varies by geographic region. For infants in the United States, vitamin K deficiency without bleeding may occur in as many as 50% of infants younger than 5 days old, with the classic hemorrhagic disease occurring in 0.25-1.7% of infants. Therefore, the Committee on Nutrition of the American Academy of Pediatrics recommends that 0.5 to 1.0 mg Vitamin K be administered to all newborns shortly after birth.

Postmenopausal and elderly women in Thailand have high risk of Vitamin K deficiency, compared with the normal value of young, reproductive females.

Current dosage recommendations for Vitamin K may be too low. The deposition of calcium in soft tissues, including arterial walls, is quite common, especially in those suffering from atherosclerosis, suggesting that Vitamin K deficiency is more common than previously thought.

Because colonic bacteria synthesize a significant portion of the Vitamin K required for human needs, individuals with disruptions to or insufficient amounts of these bacteria can be at risk for Vitamin K deficiency. Newborns, as mentioned above, fit into this category, as their colons are frequently not adequately colonized in the first five to seven days of life. (Consumption of the mother's milk can undo this temporary problem.) Another at-risk population comprises those individuals on any sort of long-term antibiotic therapy, as this can diminish the population of normal gut flora.

Menaquinone (vitamin K), but not phylloquinone (vitamin K), intake is associated with reduced risk of CHD mortality, all-cause mortality and severe aortic calcification.