o'toole grace 11100387 bloom syndrome
TRANSCRIPT
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BLOOM SYNDROME
Presentation by:Grace O’Toole aka:
Bloom–Torre–
Machacek syndrome
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History of Bloom
•1st identified by NY dermatologist Dr. David Bloom
•1st identified in 1954
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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
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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
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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
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Con’t Skin Rash
•Erythematous (reddening), telangiectatic, infiltrated, & scaly
•Appears in butterfly-shaped patch of skin across nose/cheek & back of hands
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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
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Bloom & Cancer•Elevated rate of mutation brings high risk of cancer
•Leukemia, lymphomas, & carcinomas
•Average age to develop cancer approximately 25 years old
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Identification•Confirmed
through lab test: chromosome study
•PCR assay test for chromosome 15
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Diagnosis Markers•Drastic
intrauterine growth deficiency with erythematous skin
•Small individual developing cancer
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Frequency•Found in larger
quantity in Ashkenazic Jews (carriers 1/100)
•1/50,000 people affected of Central and Easter European Jewish background
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Treatment for Identification
•Possible carriers: genetic counseling & genetic testing
•Known carriers: prenatal testing using cytogenetic or molecular methods
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Treatment for Cases•No treatment
•Preventative Measures: surveillance for cancer & decreased exposure to sunlight/X-rays
•Possibility: bone marrow transplant
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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
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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>.