Fig. 7.38 FISH.(A)Interphasenucleusfromamalepatientwithsuspectedtrisomy18.Threedifferentfluorescentprobeshavebeenusedina“FISHcocktail”;thegreenprobehybridizestotheXchromosomecentromere(one copy),theredprobetotheYchromosomecentromere(one copy),andtheaquaprobetothechromosome18centromere(three copies).(B)Ametaphasespreadinwhichtwofluorescentprobeshavebeenused,onehybridizingtochromosomeregion22q13(green) andtheotherhybridizingtochromosomeregion22q11.2(red).Therearetwo22q13signals.Oneofthetwochromosomesdoesnotstainwiththeprobefor22q11.2,indicatingamicrodeletioninthisregion.Thisabnormalitygivesrisetothe22q11.2deletionsyndrome(DiGeorgesyndrome).
(Courtesy of Dr. Nancy R.Schneider and Jeff Doolittle,Cytogenetics Laboratory,University of Texas Southwestern Medical Center,Dallas,Texas.) http://ebooksmedicine.net 2.00 1.00 0.00 number –1.00 –2.00 1.0 AA 0.8 p13.31 p12.3 p12.1
Fig. 7.39 AnalysisofcopynumbervariationviaSNPcytogenomicarray.GenomicDNAislabeledandhybridizedtoanarraycontainingpotentiallymillionsofprobespots.Copynumberisdeterminedbyoverallintensityandgenotypeisdeterminedbyallelicratio.Theexampleshownistheparmofchromosome12inapediatricleukemia.Here,thenormalareas(green) showneutral(diploid)DNAcontentandthezygosityplotshowstheexpectedratioofAA,AB,andBBSNPgenotypes.Theanomalousarea(red) showsdecreasedoverallintensity,andthezygosityplotshowslossofheterozygosity(theABgenotype);together,thesefindingsindicatethepresenceofadeletionononecopyofchromosome12p.(Modified from Paulsson K, et al: Genetic landscape of high hyper-diploid childhood acute lymphoblastic leukemia, PNAS107[50]:21719–21724, 2010.) largest containing greater than 4 million SNP probes. As a of one of the terminator nucleotides. After size separaresult, this technology is the mainstay of genomewide tion by capillary electrophoresis, the exact sequence can association studies (GWASs, described later). be “read” and compared with the normal sequence to detect the presence of mutations. Many applications of