The specific problems produced differ according to the particular abnormal synthesis involved. Common manifestations include ataxia; seizures; retinopathy; liver fibrosis; coagulopathies; failure to thrive; dysmorphic features ("e.g.," inverted nipples and subcutaneous fat pads; and strabismus. If an MRI is obtained, cerebellar atrophy and hypoplasia is a common finding.

Ocular abnormalities of CDG-Ia include: myopia, infantile esotropia, delayed visual maturation, low vision, optic disc pallor, and reduced rod function on electroretinography.

Three subtypes of CDG I (a,b,d) can cause congenital hyperinsulinism with hyperinsulinemic hypoglycemia in infancy.

Mutations in several genes have been associated with the traditional clinical syndromes, termed muscular dystrophy-dystroglycanopathies (MDDG). A new nomenclature based on clinical severity and genetic cause was recently proposed by OMIM. The severity classifications are A (severe), B (intermediate), and C (mild). The subtypes are numbered one to six according to the genetic cause, in the following order: (1) POMT1, (2) POMT2, (3) POMGNT1, (4) FKTN, (5) FKRP, and (6) LARGE.

Most common severe types include:

This disorder causes neurological problems, including mental retardation, brain atrophy and ventricular dilation, myoclonus, hypotonia, and epilepsy.

It is also associated with growth retardation, megaloblastic anemia, pectus excavatum, scoliosis, vomiting, diarrhea, and hepatosplenomegaly.

Symptoms of congenital Type III Galactosemia are apparent from birth, but vary in severity depending on whether the peripheral or generalized disease form is present. Symptoms may include:

- Infantile jaundice

- Infantile hypotonia

- Dysmorphic features

- Sensorineural hearing loss

- Impaired growth

- Cognitive deficiencies

- Depletion of cerebellar Purkinje cells

- Ovarian failure (POI) and hypertrophic hypergonadism

- Liver failure

- Renal failure

- Splenomegaly

- Cataracts

Studies of Type III galactosemia symptoms are mostly descriptive, and precise pathogenic mechanisms remain unknown. This is largely due to a lack of functional animal models of classic galactosemia. The recent development of a "Drosophila melanogaster" GALE mutant exhibiting galactosemic symptoms may yield a promising future animal model.

The syndrome causes cerebellar ataxia (balance and coordination problems), mental retardation, congenital cataracts in early childhood, muscle weakness, inability to chew food, thin brittle fingernails, and sparse hair.

Small stature, mild to severe mental retardation and dysarthria (slow, imprecise speech) are usually present.

Various skeletal abnormalities (e.g., curvature of the spine) and hypergonadotropic hypogonadism often occur.

Muscle weakness is progressive, but life expectancy is near normal.

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".

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.

Symptoms may differ greatly, as apparently modifiers control to some degree the amount of FX that is produced. Some affected individuals have few or no symptoms while others may experience life-threatening bleeding. Typically this bleeding disorder manifests itself as a tendency to easy bruising, nose bleeding, heavy and prolonged menstruation and bleeding during pregnancy and childbirth, and excessive bleeding after dental or surgical interventions. Newborns may bleed in the head, from the umbilicus, or excessively after circumcision. Other bleeding can be encountered in muscles or joints, brain, gut, or urine

While in congenital disease symptoms may be present at birth or show up later, in patients with acquired FX deficiency symptoms typically show up in later life.

Classic phosphofructokinase deficiency is the most common type of this disorder. This type presents with exercise-induced muscle cramps and weakness (sometimes rhabdomyolysis), myoglobinuria, as well as with haemolytic anaemia causing dark urine a few hours later.

Hyperuricemia is common, due to the kidneys' inability to process uric acid following damage resulting from processing myoglobin. Nausea and vomiting following strenuous exercise is another common indicator of classic PFK deficiency. Many patients will also display high levels of bilirubin, which can lead to a jaundiced appearance. Symptoms for this type of PFK deficiency usually appear in early childhood.

Diagnosis of MSS is based on clinical symptoms, magnetic resonance imaging (MRI) of the brain (cerebellar atrophy particularly involving the cerebellar vermis), and muscle biopsy.

It can be associated with mutations of the SIL1 gene, and a mutation can be found in about 50% of cases.

Differential diagnosis includes Congenital Cataracts Facial Dysmorphism Neuropathy (CCFDN), Marinesco–Sjögren like syndrome with chylomicronemia, carbohydrate deficient glycoprotein syndromes, Lowe syndrome, and mitochondrial disease.

Late-onset PFK deficiency, as the name suggests, is a form of the disease that presents later in life. Common symptoms associated with late-onset phosphofructokinase deficiency are myopathy, weakness and fatigue. Many of the more severe symptoms found in the classic type of this disease are absent in the late-onset form.

Symptoms of ML I are either present at birth or develop within the first year of life. In many infants with ML I, excessive swelling throughout the body is noted at birth. These infants are often born with coarse facial features, such as a flat nasal bridge, puffy eyelids, enlargement of the gums, and excessive tongue size (macroglossia). Many infants with ML I are also born with skeletal malformations such as hip dislocation. Infants often develop sudden involuntary muscle contractions (called myoclonus) and have red spots in their eyes (cherry red spots). They are often unable to coordinate voluntary movement (called ataxia). Tremors, impaired vision, and seizures also occur in children with ML I. Tests reveal abnormal enlargement of the liver (hepatomegaly) and spleen (splenomegaly) and extreme abdominal swelling. Infants with ML I generally lack muscle tone (hypotonia) and have mental retardation that is either initially or progressively severe. Many patients suffer from failure to thrive and from recurrent respiratory infections. Most infants with ML I die before the age of 1 year.

Glycogen storage disease type III presents during infancy with hypoglycemia and failure to thrive. Clinical examination usually reveals hepatomegaly. Muscular disease, including hypotonia and cardiomyopathy, usually occurs later. The liver pathology typically regresses as the individual enter adolescence, as does splenomegaly, should the individual so develop it.

Factor X deficiency (X as Roman numeral ten) is a bleeding disorder characterized by a lack in the production of factor X (FX), an enzyme protein that causes blood to clot in the coagulation cascade. Produced in the liver FX when activated cleaves prothrombin to generate thrombin in the intrinsic pathway of coagulation. This process is vitamin K dependent and enhanced by activated factor V.

The condition may be inherited or, more commonly, acquired.

The term fatty acid oxidation disorder (FAOD) is sometimes used, especially when there is an emphasis on the oxidation of the fatty acid.

In addition to the fetal complications, they can also cause complications for the mother during pregnancy.

Examples include:

- trifunctional protein deficiency

- MCADD, LCHADD, and VLCADD

Glycogen storage disease type III is an autosomal recessive metabolic disorder and inborn error of metabolism (specifically of carbohydrates) characterized by a deficiency in glycogen debranching enzymes. It is also known as Cori's disease in honor of the 1947 Nobel laureates Carl Cori and Gerty Cori. Other names include Forbes disease in honor of clinician Gilbert Burnett Forbes (1915–2003), an American Physician who further described the features of the disorder, or limit dextrinosis, due to the limit dextrin-like structures in cytosol. Limit dextrin is the remaining polymer produced after hydrolysis of glycogen. Without glycogen debranching enzymes to further convert these branched glycogen polymers to glucose, limit dextrinosis abnormally accumulates in the cytoplasm.

Glycogen is a molecule the body uses to store carbohydrate energy. Symptoms of GSD-III are caused by a deficiency of the enzyme amylo-1,6 glucosidase, or debrancher enzyme. This causes excess amounts of an abnormal glycogen to be deposited in the liver, muscles and, in some cases, the heart.

Symptomatic presentation usually occurs between 6 and 24 months of age, but the majority of cases have been documented in children less than 1 year of age. The infantile form involves multiple organ systems and is primarily characterized by hypoketotic hypoglycemia (recurring attacks of abnormally low levels of fat breakdown products and blood sugar) that often results in loss of consciousness and seizure activity. Acute liver failure, liver enlargement, and cardiomyopathy are also associated with the infantile presentation of this disorder. Episodes are triggered by febrile illness, infection, or fasting. Some cases of sudden infant death syndrome are attributed to infantile CPT II deficiency at autopsy.

This exclusively myopathic form is the most prevalent and least severe phenotypic presentation of this disorder. Characteristic signs and symptoms include rhabdomyolysis (breakdown of muscle fibers and subsequent release of myoglobin), myoglobinuria, recurrent muscle pain, and weakness. It is important to note that muscle weakness and pain typically resolves within hours to days, and patients appear clinically normal in the intervening periods between attacks. Symptoms are most often exercise-induced, but fasting, a high-fat diet, exposure to cold temperature, or infection (especially febrile illness) can also provoke this metabolic myopathy. In a minority of cases, disease severity can be exacerbated by three life-threatening complications resulting from persistent rhabdomyolysis: acute kidney failure, respiratory insufficiency, and episodic abnormal heart rhythms. Severe forms may have continual pain from general life activity. The adult form has a variable age of onset. The first appearance of symptoms usually occurs between 6 and 20 years of age but has been documented in patients as young as 8 months as well as in adults over the age of 50. Roughly 80% cases reported to date have been male.

A broad classification for genetic disorders that result from an inability of the body to produce or utilize one enzyme that is required to oxidize fatty acids. The enzyme can be missing or improperly constructed, resulting in it not working. This leaves the body unable to produce energy within the liver and muscles from fatty acid sources.

The body's primary source of energy is glucose; however, when all the glucose in the body has been expended, a normal body digests fats. Individuals with a fatty-acid metabolism disorder are unable to metabolize this fat source for energy, halting bodily processes. Most individuals with a fatty-acid metabolism disorder are able to live a normal active life with simple adjustments to diet and medications.

If left undiagnosed many complications can arise. When in need of glucose the body of a person with a fatty-acid metabolism disorder will still send fats to the liver. The fats are broken down to fatty acids. The fatty acids are then transported to the target cells but are unable to be broken down, resulting in a build-up of fatty acids in the liver and other internal organs.

Fatty-acid metabolism disorders are sometimes classified with the lipid metabolism disorders, but in other contexts they are considered a distinct category.

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.

LAD was first recognized as a distinct clinical entity in the 1970s. The classic descriptions of LAD included recurrent bacterial infections, defects in neutrophil adhesion, and a delay in umbilical cord sloughing. The adhesion defects result in poor leukocyte chemotaxis, particularly neutrophil, inability to form pus and neutrophilia.

Individuals with LAD suffer from bacterial infections beginning in the neonatal period. Infections such as omphalitis, pneumonia, gingivitis, and peritonitis are common and often life-threatening due to the infant's inability to properly destroy the invading pathogens. These individuals do not form abscesses because granulocytes cannot migrate to the sites of infection.

PDCD is generally presented in one of two forms. The metabolic form appears as lactic acidosis. The neurological form of PDCD contributes to hypotonia, poor feeding, lethargy and structural abnormalities in the brain. Patients may develop seizures and/or neuropathological spasms. These presentations of the disease usually progress to mental retardation, microcephaly, blindness and spasticity.

Females with residual pyruvate dehydrogenase activity will have no uncontrollable systemic lactic acidosis and few, if any, neurological symptoms. Conversely, females with little to no enzyme activity will have major structural brain abnormalities and atrophy. Males with mutations that abolish, or almost abolish, enzyme activity presumably die in utero because brain cells are not able to generate enough ATP to be functionally viable. It is expected that most cases will be of mild severity and have a clinical presentation involving lactic acidosis.

Prenatal onset may present with non-specific signs such as low Apgar scores and small for gestational age. Metabolic disturbances may also be considered with poor feeding and lethargy out of proportion to a mild viral illness, and especially after bacterial infection has been ruled out. PDH activity may be enhanced by exercise, phenylbutyrate and dichloroacetate.

The clinical presentation of congenital PDH deficiency is typically characterized by heterogenous neurological features that usually appear within the first year of life. In addition, patients usually show severe hyperventillation due to profound metabolic acidosis mostly related to lactic acidosis. Metabolic acidosis in these patients is usually refractory to correction with bicarbonate.

There are three main types of the disease each with its own distinctive symptoms.

Type I infantile form, infants will develop normally until about a year old. At this time, the affected infant will begin to lose previously acquired skills involving the coordination of physical and mental behaviors. Additional neurological and neuromuscular symptoms such as diminished muscle tone, weakness, involuntary rapid eye movements, vision loss, and seizures may become present. With time, the symptoms worsen and children affected with this disorder will experience a decreased ability to move certain muscles due to muscle rigidity. The ability to respond to external stimuli will also decrease. Other symptoms include neuroaxonal dystrophy from birth, discoloration of skin, Telangiectasia or widening of blood vessels.

Type II adult form, symptoms are milder and may not appear until the individual is in his or her 30s. Angiokeratomas, an increased coarsening of facial features, and mild intellectual impairment are likely symptoms.

Type III is considered an intermediate disorder. Symptoms vary and can include to be more severe with seizures and mental retardation, or less severe with delayed speech, a mild autistic like presentation, and/or behavioral problems.

MPS VII, Sly syndrome, one of the least common forms of the mucopolysaccharidoses, is estimated to occur in fewer than one in 250,000 births. The disorder is caused by deficiency of the enzyme beta-glucuronidase. In its rarest form, Sly syndrome causes children to be born with hydrops fetalis, in which extreme amounts of fluid are retained in the body. Survival is usually a few months or less. Most children with Sly syndrome are less severely affected. Neurological symptoms may include mild to moderate intellectual disability by age 3, communicating hydrocephalus, nerve entrapment, corneal clouding, and some loss of peripheral and night vision. Other symptoms include short stature, some skeletal irregularities, joint stiffness and restricted movement, and umbilical and/or inguinal hernias. Some patients may have repeated bouts of pneumonia during their first years of life. Most children with Sly syndrome live into the teenage or young adult years.

Signs and symptoms of CTLN1 in infants are caused by increasing levels of ammonia in the blood and cerebrospinal fluid and include excessive vomiting, anorexia, refusal to eat, irritability, increased intracranial pressure, and worsening lethargy, seizures, hypotonia, respiratory distress, hepatomegaly, and cerebral edema. These symptoms appear within days of birth in the more severe forms of the disease with complete deficiency of the enzyme. As ammonia accumulates further, the affected infant may enter a hyperammonemic coma, which indicates neurological damage and can cause developmental delays, cognitive disabilities, cerebral palsy, hypertonia, spasticity, ankle clonus, seizures, and liver failure.

Milder forms of the disease are caused by partial arginosuccinate synthetase deficiency and may manifest in childhood or in adulthood. Symptoms of mild CTLN1 include failure to thrive, avoidance of high-protein foods, ataxia, worsening lethargy, and vomiting. Hyperammonemic coma can still develop in these people. CTLN1 can also develop in the perinatal period.