Congenital dyserythropoietic anemia type IV is an autosomal dominant inherited red blood cell disorder characterized by ineffective erythropoiesis and hemolysis resulting in anemia. Circulating erythroblasts and erythroblasts in the bone marrow show various morphologic abnormalities. Affected individuals with CDAN4 also have increased levels of fetal hemoglobin.

CDA type I is characterized by moderate to severe anemia. It is usually diagnosed in childhood or adolescence, although in some cases, the condition can be detected before birth.

Treatment of individuals with CDA usually consist of frequent blood transfusions, but this can vary depending on the type that the individual has. Patients report going every 2–3 weeks for blood transfusions. In addition, they must undertake chelation therapy to survive; either deferoxamine, deferasirox, or deferiprone to eliminate the excess iron that accumulates. Removal of the spleen and gallbladder are common. Hemoglobin levels can run anywhere between 8.0 g/dl and 11.0 g/dl in untransfused patients, the amount of blood received by the patient is not as important as their baseline pre-transfusion hemoglobin level. This is true for ferritin levels and iron levels in the organs as well, it is important for patients to go regularly for transfusions in order to maximize good health, normal ferritin levels run anywhere between 24 and 336 ng/ml, hematologists generally do not begin chelation therapy until ferritin levels reach at least 1000 ng/ml. It is more important to check iron levels in the organs through MRI scans, however, than to simply get regular blood tests to check ferritin levels, which only show a trend, and do not reflect actual organ iron content.

The diagnosis of congenital dyserythropoietic anemia can be done via sequence analysis of the entire coding region, types I, II, III and IV ( is a relatively new form of CDA that had been found, just 4 cases have been reported) according to the genetic testing registry.

CDA type I is transmitted by both parents autosomal recessively and usually results from mutations in the CDAN1 gene. Little is known about the function of this gene, and it is unclear how mutations cause the characteristic features of CDA type I. Some people with this condition do not have identified mutations in the CDAN1 gene, leading researchers to believe that mutations in at least one other gene can also cause this form of the disorder.

Congenital dyserythropoietic anemia type IV (CDA IV) has been described with typical morphologic features of CDA II but a negative acidified-serum test.

CDA type III is transmitted autosomal dominantly. The genetic cause of CDA type III is known to be a problem with the KIF23 gene, located on the long arm of chromosome 15 at a position designated 15q22.

Congenital dyserythropoietic anemia type III (CDA III) is a rare autosomal dominant disorder characterized by macrocytic anemia, bone marrow erythroid hyperplasia and giant multinucleate erythroblasts. New evidence suggests that this may be passed on recessively as well.

Some people have a history of exposure to chemotherapy (especially alkylating agents such as melphalan, cyclophosphamide, busulfan, and chlorambucil) or radiation (therapeutic or accidental), or both (e.g., at the time of stem cell transplantation for another disease). Workers in some industries with heavy exposure to hydrocarbons such as the petroleum industry have a slightly higher risk of contracting the disease than the general population. Xylene and benzene exposure has been associated with myelodysplasia. Vietnam veterans exposed to Agent Orange are at risk of developing MDS. A link may exist between the development of MDS "in atomic-bomb survivors 40 to 60 years after radiation exposure" (in this case, referring to people who were in close proximity to the dropping of the atomic bomb in Hiroshima and Nagasaki during World War II).

Children with Down syndrome are susceptible to MDS, and a family history may indicate a hereditary form of sideroblastic anemia or Fanconi anemia.

Congenital dyserythropoietic anemia type II (CDA II), or hereditary erythroblastic multinuclearity with positive acidified serum lysis test (HEMPAS) is a rare genetic anemia in humans characterized by hereditary erythroblastic multinuclearity with positive acidified serum lysis test.

Although not yet formally incorporated in the generally accepted classification systems, molecular profiling of myelodysplastic syndrome genomes has increased the understanding of prognostic molecular factors for this disease. For example, in low-risk MDS, "IDH1" and "IDH2" mutations are associated with significantly worsened survival.

The anemia associated with CDA type II can range from mild to severe, and most affected individuals have jaundice, hepatosplenomegaly, and the formation of hard deposits in the gallbladder called bilirubin gallstones. This form of the disorder is usually diagnosed in adolescence or early adulthood. An abnormal buildup of iron typically occurs after age 20, leading to complications including heart disease, diabetes, and cirrhosis.

RA has been found among alcohol-dependent patients who suffer from Korsakoff's syndrome. Korsakoff's syndrome patients suffer from retrograde amnesia due to a thiamine deficiency (lack of vitamin B1). Also, chronic alcohol use disorders are associated with a decrease in volume of the left and right hippocampus.

These patients' regular diet consists mostly of hard alcohol intake, which lacks the necessary nutrients for healthy development and maintenance. Therefore, after a prolonged time consuming primarily alcohol, these people undergo memory difficulties and ultimately suffer from RA. However, some of the drawback of using Korsakoff patients to study RA is the progressive nature of the illness and the unknown time of onset.

Traumatic brain injury (TBI), also known as post-traumatic amnesia, occurs from an external force that causes structural damage to the brain, such as a sharp blow to the head, a diffuse axonal injury, or childhood brain damage (e.g., shaken baby syndrome). In cases of sudden rapid acceleration, the brain continues moving around in the skull, harming brain tissue as it hits internal protrusions.

TBI varies according to impact of external forces, location of structural damage, and severity of damage ranging from mild to severe. Retrograde amnesia can be one of the many consequences of brain injury but it is important to note that it is not always the outcome of TBI. An example of a subgroup of people who are often exposed to TBI are individuals who are involved in high-contact sports. Research on football players takes a closer look at some of the implications to their high-contact activities. Enduring consistent head injuries can have an effect on the neural consolidation of memory.

Specific cases, such as that of patient ML, support the evidence that severe blows to the head can cause the onset of RA. In this specific case there was an onset of isolated RA following a severe head injury. The brain damage did not affect the person's ability to form new memories. Therefore, the idea that specific sections of retrograde memory are independent of anterograde is supported. Normally, there is a very gradual recovery, however, a dense period of amnesia immediately preceding the trauma usually persists.