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BLOOM SYNDROME
Presentation by:Grace O’Toole aka:
Bloom–Torre–
Machacek syndrome
History of Bloom
•1st identified by NY dermatologist Dr. David Bloom
•1st identified in 1954
Cause of Bloom• Autosomal recessive gene
characterized by high levels of sister chromatids
• Syndrome problem on chromosome 15
• Cells have genomic instability with excessive homologous recombination
• Increase in chromosome breakage/rearrangement
Cause: BLM gene•Gene encoding protein
RecQL3 helicase
•Mutation of BLM gene inactivate BLM protein’s DNA helicase activity or nullify protein expression
•Lack of BLM leads to increase mutations
Symptoms“Clinical Features”• Short stature
• Rash developing from sun exposure
• High pitched voice
• Facial features: long/narrow face, micrognathism (undersized jaw), prominent nose/ears
• Skin pigmentation change: hypo/hyper-pigment & cafe-au-lait spots (pigmented birthmarks)
• Telangiectasis (dilation of capillaries to appear red) in eyes
Con’t Skin Rash
•Erythematous (reddening), telangiectatic, infiltrated, & scaly
•Appears in butterfly-shaped patch of skin across nose/cheek & back of hands
Con’t Symptoms• Moderate immune deficiency {specifically
immunoglobulin classes} leads to recurrent pneumonia & ear infection
• Hypogonadism (failure to produce sperm) so infertile males
• Premature menopause for women
Complications-Chronic lung problems-Diabetes-Learning disabilities-Small # of mental retardation cases-Susceptibility to cancer
Bloom & Cancer•Elevated rate of mutation brings high risk of cancer
•Leukemia, lymphomas, & carcinomas
•Average age to develop cancer approximately 25 years old
Identification•Confirmed
through lab test: chromosome study
•PCR assay test for chromosome 15
Diagnosis Markers•Drastic
intrauterine growth deficiency with erythematous skin
•Small individual developing cancer
Frequency•Found in larger
quantity in Ashkenazic Jews (carriers 1/100)
•1/50,000 people affected of Central and Easter European Jewish background
Treatment for Identification
•Possible carriers: genetic counseling & genetic testing
•Known carriers: prenatal testing using cytogenetic or molecular methods
Treatment for Cases•No treatment
•Preventative Measures: surveillance for cancer & decreased exposure to sunlight/X-rays
•Possibility: bone marrow transplant
Bioethical Consequences
•Ethical problems to consider:
•Gene testing to be carriers calls into question for risk of child to be affected
•Sibling contempt with smaller sized Bloom Syndrome child compared to child not afflicted
Bibliography•Baxter, Sarah. "BLM Gene
Encodes a RecQ Helicase." Davidson.edu. Davidson College Molecular Biology, n.d. Web. 25 Feb. 2013. <http://www.google.com/imgres?imgurl=http://www.bio.davidson.edu/Courses/Molbio/MolStudents/spring2003/Baxter/BLM.gif>.
•O'Neil, Marla J. "Bloom Syndrome; BLM." Omim. Omim, Oct.-Nov. 2009. Web. 25 Feb. 2013. <http://omim.org/entry/210900>.