3/23/2010
Dr. B.D. Gowreesunkur
Director
Green Cross Medical Laboratory
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Duchenne / Becker
Muscular Dystrophy
¾Highly elevated CK in young children
¾X
X-linked
linked – Dystrophin Gene
y 2.4Mb - 79 Exons
¾Females are carriers, Boys are affected
¾Vast mutation spectrum
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DMD/ BMD
¾Mutations
y Point mutations
y Whole exon deletions/duplications
y Small insertions/deletion
y Non sense, frameshift (truncating protein)
¾Upto
p 10% Mosaicism
y No mutation detected in Mother of boys
with known mutations
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Screening – QF PCR
y DNA Quality
y Test
y 2 Multiplexes of14 Exons
y ABI 3100 Genetic Analyser
y Analysed on Software and Excel sheet
y Detect female
f
l carrier status, duplicated
d l
d
males/ females
¾Detects 99% del, 96% Dup & >1bp
ins/del
¾However, only accounts for ~ 65-70%
dystrophin mutations
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¾Full Screen
Full Screen
y Full DMD gene screening (12 multiplexes,
7 exons each)
y Heteroduplex analysis
y QF PCR all exons
y Both done on ABI 3100 Genetic Analyser
¾Gene Sequencing
¾PTT (Muscle biopsy - mosaicism)
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Fragile X Syndrome
¾ Mutation on FMR1
y CGG Repeat > 200
¾ Elongated face, large or
protruding ears,
ears flat feet,
feet
MR, speech problems
¾ Affects 1 in 3600 males
and 1 in 4000-6000
Females
¾ PCR for up to 200 repeats
and Southern Blot
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Down’s Syndrome
¾1 in 800 to 1000 births worldwide
¾Trisomy 21 (full or part)
y Meiotic Non-dysjunction
y Full Trisomy 21 – 95% of Down’s
y 88% - maternal
¾Maternal Age Risk
¾Amniocentesis, CVS
y Karyotyping,
y yp g, FISH
y QF-PCR
¾Triple Test
y bHCG AFP, E2
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PCR –GOLD STANDARD BY
WHO AND CDC
¾Rapid, Ultra Sensitive and Specific
¾CHIK, H1N1, MTB, Chlamydia etc.,
¾Detects DNA unique to pathogen
¾Accurately pick-up virus even in mild
infections
¾Used for Viral Loads (Hep B
B, C
C, HIV)
¾Human Papilloma Virus- cervical cancer
¾Septicaemia
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