Bloom's syndrome is characterized by severe prenatal and postnatal growth retardation and a sun-sensitive erythematous skin lesion that occurs most commonly on the face. Recurrent infections (otitis media and pneumonia), chronic pulmonary disease, and diabetes mellitus are common. Many have learning disabilities. Males are infertile; females enter menopause prematurely.
Characteristics commonly seen in Bloom's syndrome are small stature (average adult male height of 151 cm, average adult female height of 144 cm), skin photosensitivity, and a high-pitched voice. A typical facial appearance has also been described consisting of a narrow face with prominent nose and prominent ears. Immunodeficiency has been seen, which results in an increased number of respiratory tract and ear infections.
Mutations in the Bloom syndrome , which is a member of the DNA helicas family. DNA helicases are enzymes that unwind the two spiral strands of a DNA molecule so that they can be copied. When a cell prepares to divide to form two cells, the chromosomes are duplicated so that each new cell will get a complete set of chromosomes; this replication process involves unwinding the DNA so that it can be copied. The BLM protein is important in maintaining the stability of the DNA during this process.
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Causes
Bloom syndrome is apparent from birth with affected newborns being unusually small. Most parents seek medical help when the infant does not grow normally. Over 50% of children are significantly underdeveloped in physical stature until age 8 years, and most fail to reach 1.5 metres (5 feet) in adulthood.
Bloom's Syndrome is inherited in an autosomal recessive pattern, which means two copies of the gene must be altered for a person to be affected by the disorder. The gene for Bloom’s syndrome is located on chromosome 15; one particular mutation in the gene has been identified as the cause of Bloom’s syndrome in the vast majority of Ashkenazi Jews.
Diagnosis
The diagnosis of Bloom’s syndrome can be confirmed or ruled out by a laboratory test known as a chromosome study, as blood and skin cells show a characteristic pattern of chromosome breakage and rearrangement. Recently, the gene for Bloom’s syndrome was isolated. The gene is located on chromosome 15, and one particular mutation in the gene has been identified as the cause of Bloom’s syndrome in the vast majority of Ashkenazi Jews. Because of these recent findings, both carrier testing and prenatal diagnosis for Bloom’s syndrome are now available.
Treatment
There is no treatment for the underlying cause of Bloom’s syndrome, and therefore medical intervention is primarily preventative. Adults with Bloom’s syndrome should be more attentive and cautious than others in their surveillance for cancer. It is recommended that people afflicted by this disease maintain close contact with a physician familiar with Bloom’s.
By : peterhutch
