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

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.

Renal failure is the major cause of morbidity and mortality in complete LCAT deficiency, while in partial deficiency (fish eye disease) major cause of morbidity is visual impairment due to corneal opacity. These patients have low HDL cholesterol but surprisingly premature atherosclerosis is not seen. However, there are some reported cases.

Galactose epimerase deficiency, also known as GALE deficiency, Galactosemia III and UDP-galactose-4-epimerase deficiency, is a rare, autosomal recessive form of galactosemia associated with a deficiency of the enzyme "galactose epimerase".

Canine phosphofructokinase deficiency is found mostly in English Springer Spaniels and American Cocker Spaniels, but has also been reported in Whippets and Wachtelhunds. Mixed-breed dogs descended from any of these breeds are also at risk to inherit PFK deficiency.

Glycogen storage disease type VI (GSD VI) is a type of glycogen storage disease caused by a deficiency in liver glycogen phosphorylase or other components of the associated phosphorylase cascade system. It is also known as "Hers' disease", after Henri G. Hers, who characterized it in 1959. The scope of GSD VI now also includes glycogen storage disease type VIII, IX (caused by phosphorylase b kinase deficiency) and X (deficiency protein kinase A).

The incidence of GSD VI is approximately 1 case per 65,000–85,000 births, representing approximately 30% all cases of glycogen storage disease. Approximately 75% of these GSD VI cases result from the X-linked recessive forms of phosphorylase kinase deficiency, all other forms are autosomal recessive.

The human GALK1 gene contains 8 exons and spans approximately 7.3 kb of genomic DNA. The GALK1 promoter was found to have many features in common with other housekeeping genes, including high GC content, several copies of the binding site for the Sp1 transcription factor and the absence of TATA-box and CCAAT-box motifs typically present in eukaryotic polymerase II promoters. Analysis by 5-prime-RACE PCR indicated that the GALK1 mRNA is heterogeneous at the 5-prime end, with transcription sites occurring at many locations between 21 and 61 bp upstream of the ATG start site of the coding region. In vitro translation experiments of the GALK1 cDNA indicated that the protein is cytosolic and not associated with endoplasmic reticulum membrane.

Galactokinase deficiency, also known as Galactosemia type 2 or GALK deficiency, is an autosomal recessive metabolic disorder marked by an accumulation of galactose and galactitol secondary to the decreased conversion of galactose to galactose-1-phosphate by galactokinase. The disorder is caused by mutations in the GALK1 gene, located on chromosome 17q24. Galactokinase catalyzes the first step of galactose phosphorylation in the Leloir pathway of intermediate metabolism. Galactokinase deficiency is one of the three inborn errors of metabolism that lead to hypergalactosemia. The disorder is inherited as an autosomal recessive trait. Unlike classic galactosemia, which is caused by deficiency of galactose-1-phosphate uridyltransferase, galactokinase deficiency does not present with severe manifestations in early infancy. Its major clinical symptom is the development of cataracts during the first weeks or months of life, as a result of the accumulation, in the lens, of galactitol, a product of an alternative route of galactose utilization. The development of early cataracts in homozygous affected infants is fully preventable through early diagnosis and treatment with a galactose-restricted diet. Some studies have suggested that, depending on milk consumption later in life, heterozygous carriers of galactokinase deficiency may be prone to presenile cataracts at 20–50 years of age.

In order to get Tarui’s disease, both parents must be carriers of the genetic defect so that the child is born with the full form of the recessive trait. The best indicator of risk is a family member with PFK deficiency.

Individuals presenting with Type III galactosemia must consume a lactose- and galactose-restricted diet devoid of dairy products and mucilaginous plants. Dietary restriction is the only current treatment available for GALE deficiency. As glycoprotein and glycolipid metabolism generate endogenous galactose, however, Type III galactosemia may not be resolved solely through dietary restriction.

Galactose-1-phosphate uridylyltransferase deficiency, also called galactosemia type 1, classic galactosemia or GALT deficiency, is the most common type of galactosemia, an inborn error of galactose metabolism, caused by a deficiency of the enzyme galactose-1-phosphate uridylyltransferase. It is an autosomal recessive metabolic disorder that can cause liver disease and death if untreated. Treatment of galactosemia is most successful if initiated early and includes dietary restriction of lactose intake. Because early intervention is key, galactosemia is included in newborn screening programs in many areas. On initial screening, which often involves measuring the concentration of galactose in blood, classic galactosemia may be indistinguishable from other inborn errors of galactose metabolism, including galactokinase deficiency and galactose epimerase deficiency. Further analysis of metabolites and enzyme activities are needed to identify the specific metabolic error.

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.

Lecithin cholesterol acyltransferase deficiency (LCAT deficiency) is a disorder of lipoprotein metabolism. The disease has two forms: Familial LCAT deficiency, in which there is complete LCAT deficiency, and Fish-eye disease, in which there is a partial deficiency.

Lecithin cholesterol acyltransferase catalyzes the formation of cholesterol esters in lipoproteins.

Inherited or congenital FX deficiency is passed on by autosomal recessive inheritance. A person needs to inherit a defective gene from both parents. People who have only one defective gene usually do not exhibit the disease, but can pass the gene on to half their offspring. Different genetic mutations have been described.

In persons with congenital FX deficiency the condition is lifelong. People affected should alert other family members as they may also have the condition or carry the gene. In the general population the condition affects about 1 in 1 million people. However, the prevalence may be higher as not all individuals may express the disease and be diagnosed.

In the acquired form of FX deficiency an insufficient amount of factor X is produced by the liver due to liver disease, vitamin K deficiency, buildup of abnormal proteins in organs (amyloidosis) or certain medications (i.e. warfarin). In amyloidosis FX deficiency develops as FX and other coagulation factors are absorbed by amyloid fibrils.

There is no cure for GALT deficiency, in the most severely affected patients, treatment involves a galactose free diet for life. Early identification and implementation of a modified diet greatly improves the outcome for patients. The extent of residual GALT enzyme activity determines the degree of dietary restriction. Patients with higher levels of residual enzyme activity can typically tolerate higher levels of galactose in their diets. As patients get older, dietary restriction is often relaxed. With the increased identification of patients and their improving outcomes, the management of patients with galactosemia in adulthood is still being understood.

After diagnosis, patients are often supplemented with calcium and vitamin D3. Long-term manifestations of the disease including ovarian failure in females, ataxia. and growth delays are not fully understood. Routine monitoring of patients with GALT deficiency includes determining metabolite levels (galactose 1-phosphate in red blood cells and galactitol in urine) to measure the effectiveness of and adherence to dietary therapy, ophthalmologic examination for the detection of cataracts and assessment of speech, with the possibility of speech therapy if developmental verbal dyspraxia is evident.

Arakawa's syndrome II is inherited in an autosomal dominant manner. This means the defective gene responsible for disorder is located on an autosome, and one copy of the defective gene is sufficient to cause the disorder when inherited from a parent who has the disorder.

Arakawa's syndrome II is an autosomal dominant metabolic disorder that causes a deficiency of the enzyme tetrahydrofolate-methyltransferase; affected individuals cannot properly metabolize methylcobalamin, a type of Vitamin B.

It is also called Methionine synthase deficiency, Tetrahydrofolate-methyltransferase deficiency syndrome, and N5-methylhomocysteine transferase deficiency.

Lysosomal storage diseases (LSDs; ) are a group of about 50 rare inherited metabolic disorders that result from defects in lysosomal function. Lysosomes are sacs of enzymes within cells that digest large molecules and pass the fragments on to other parts of the cell for recycling. This process requires several critical enzymes. If one of these enzymes is defective, because of a mutation, the large molecules accumulate within the cell, eventually killing it.

Lysosomal storage disorders are caused by lysosomal dysfunction usually as a consequence of deficiency of a single enzyme required for the metabolism of lipids, glycoproteins (sugar-containing proteins), or so-called mucopolysaccharides. Individually, LSDs occur with incidences of less than 1:100,000; however, as a group, the incidence is about 1:5,000 - 1:10,000. Most of these disorders are autosomal recessively inherited such as Niemann–Pick disease, type C, but a few are X-linked recessively inherited, such as Fabry disease and Hunter syndrome (MPS II).

The lysosome is commonly referred to as the cell's recycling center because it processes unwanted material into substances that the cell can use. Lysosomes break down this unwanted matter by enzymes, highly specialized proteins essential for survival. Lysosomal disorders are usually triggered when a particular enzyme exists in too small an amount or is missing altogether. When this happens, substances accumulate in the cell. In other words, when the lysosome does not function normally, excess products destined for breakdown and recycling are stored in the cell.

Like other genetic disorders, individuals inherit lysosomal storage diseases from their parents. Although each disorder results from different gene mutations that translate into a deficiency in enzyme activity, they all share a common biochemical characteristic – all lysosomal disorders originate from an abnormal accumulation of substances inside the lysosome.

LSDs affect mostly children and they often die at a young and unpredictable age, many within a few months or years of birth. Many other children die of this disease following years of suffering from various symptoms of their particular disorder.

Ribose-5-phosphate isomerase deficiency (RPI deficiency, OMIM #608611) is a human disorder caused by mutations in the pentose phosphate pathway enzyme ribose-5-phosphate isomerase. With a single diagnosed patient over a 27-year period, RPI deficiency is currently the rarest disease in the world.

Carnosinemia, also called carnosinase deficiency or aminoacyl-histidine dipeptidase deficiency, is a rare autosomal recessive metabolic disorder caused by a deficiency of "carnosinase", a dipeptidase (a type of enzyme that splits dipeptides into their two amino acid constituents).

Carnosine is a dipeptide composed of beta-alanine and histidine, and is found in skeletal muscle and cells of the nervous system. This disorder results in an excess of carnosine in the urine, cerebrospinal fluid (CSF), blood and nervous tissue. Neurological disorders associated with a deficiency of carnosinase, and the resulting carnosinemia ("carnosine in the blood") are common.

The prevalence of Molybdenum co-factor deficiency is estimated as being between 1 in 100 000 and 1 in 200 000. To date more than 100 cases have been reported. However, this may significantly under represent cases.

Since the report of this first case in 1999, no further patients have been diagnosed. In the search for an explanation for this rarity, it has been found that the patient has a seldom-seen allelic combination. One allele is a non-functional null allele, while the other encodes for a partially active enzyme. Furthermore, the partially functional allele has expression deficits that depend on the cell type in which it is expressed. Therefore, some of the patient's cells have a considerable amount of RPI activity, whereas others do not.

The molecular cause of the pathology is not fully understood. One hypothesis is that ribose-5-phosphate may lack for RNA synthesis; another possibility is that the accumulation of D-ribitol and D-arabitol may be toxic.

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.

The GM1 gangliosidoses (or GM1 gangliosidos"i"s) are caused by a deficiency of beta-galactosidase, with resulting abnormal storage of acidic lipid materials in cells of the central and peripheral nervous systems, but particularly in the nerve cells.

GM1 Gangliosidoses are inherited, autosomal recessive sphingolipidoses, resulting from marked deficiency of Acid Beta Galactosidase.

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.