5q- syndrome

Alternate names

5q deletion syndrome; Refractory macrocytic anemia due to 5q deletion; MAR; 5q syndrome; 5q minus syndrome

Definition

5q minus (5q-) syndrome is a type of bone marrow disorder called myelodysplastic syndrome (MDS). MDS comprises a group of conditions in which immature blood cells fail to develop normally, resulting in too many immature cells and too few normal mature blood cells.

Summary

• In 5q- syndrome, development of red blood cells is particularly affected, leading to a shortage of these cells (anemia).
• In addition, the red blood cells that are present are unusually large (macrocytic).
• Individuals with 5q- syndrome also have abnormal development of bone marrow cells called megakaryocytes, which produce platelets, the cells involved in blood clotting.
• A common finding in people with 5q- syndrome is abnormal cells described as hypolobated megakaryocytes.
• In addition, some individuals with 5q- syndrome have an excess of platelets, while others have normal numbers of platelets.
• MDS is considered a slow-growing (chronic) blood cancer.
• It can progress to a fast-growing blood cancer called acute myeloid leukemia (AML).
• Progression to AML occurs less commonly in people with 5q- syndrome than in those with other forms of MDS.

Epidemiology

MDS affects nearly 1 in 20,000 people in the United States. It is thought that 5q- syndrome accounts for 15 percent of MDS cases. Unlike other forms of MDS, which occur more frequently in men than women, 5q- syndrome is more than twice as common in women.

Cause

• 5q- syndrome is caused by deletion of a region of DNA from the long (q) arm of chromosome 5.
• Most people with 5q- syndrome are missing a sequence of about 1.5 million DNA building blocks (base pairs), also written as 1.5 megabases (Mb). However, the size of the deleted region varies.
• This deletion occurs in immature blood cells during a person's lifetime and affects one of the two copies of chromosome 5 in each cell.
• The commonly deleted region of DNA contains 40 genes, many of which play a critical role in normal blood cell development.
• Research suggests that loss of multiple genes in this region contributes to the features of 5q- syndrome.
• Loss of the RPS14 gene leads to the problems with red blood cell development characteristic of 5q- syndrome, and loss of MIR145 or MIR146A contributes to the megakaryocyte and platelet abnormalities and may promote the overgrowth of immature cells.
• Scientists are still determining how the loss of other genes in the deleted region might be involved in the features of 5q- syndrome.

Inheritance

This condition is generally not inherited but arises from a mutation in the body's cells that occurs after conception. This alteration is called a somatic mutation. Affected people typically have no history of the disorder in their family.

Symptoms

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

30%-79% of people have these symptoms

• Bone marrow hypercellularity
• Erythroid hypoplasia
• Increased lactate dehydrogenase level
• Macrocytic anemia
• Megakaryocyte nucleus hypolobulation
• Thrombocytosis(Increased number of platelets in blood)

5%-29% of people have these symptoms

• Abnormal bleeding(Bleeding tendency)
• Abnormality of bone marrow stromal cells
• Abnormality of neutrophil morphology
• Acute myeloid leukemia
• Anisocytosis(Unequal size of red blood cells)
• Bone marrow hypocellularity(Bone marrow failure)
• Chronic infection
• Leukopenia(Decreased blood leukocyte number)
• Multiple lineage myelodysplasia

Diagnosis

Clinical tests

• Cytogenetics Tests
• Fluorescence in situ hybridization (FISH)
• Molecular Genetics Tests
• Deletion/duplication analysis

above test are used for diagnosis

Treatment

• Lenalidomide has activity in 5q- syndrome and is FDA approved for red blood cell (RBC) transfusion-dependent anemia due to low or intermediate-1 (int-1) risk myelodysplastic syndrome (MDS) associated with chromosome 5q deletion with or without additional cytogenetic abnormalities.
• There are several possible mechanisms that link the haploinsufficiency molecular lesions with lenalidomide sensitivity.

Prognosis

Most affected people have a stable clinical course but are often transfusion dependent.

NIH genetic and rare disease info

• NIH info on 5q- syndrome

5q- syndrome is a rare disease.

5q- syndrome Resources
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