In this report we demonstrate the role of fluorescence in situ hybridisation (FISH) and conventional cytogenetic methods in clinically and cytogenetically confirmed cases of microdeletion syndromes. A total of nine cases were referred to the Cytopathology and Cytogenetic Unit, Hospital Universiti Kebangsaan Malaysia (HUKM) from 2002 to 2004. They include three Prader-Willi syndrome, three DiGeorge syndrome, one Williams syndrome, one Miller-Dieker syndrome and one Kallmann syndrome.Blood samples from the patients were cultured and harvested following standard procedures. Twenty metaphases were analysed for each of the cases. FISH analysis was carried out for all the cases using commercial probes (Vysis, USA): SNRPN and D15S10 for Prader-Willi syndrome, LIS1 for Miller Dieker syndrome, ELN for Williams syndrome, KAL for Kallmann syndrome, TUPLE 1 and D22S75 for DiGeorge syndrome. Conventional cytogenetic analysis revealed normal karyotypes in all but one case with structural abnormality involving chromosomes 9 and 22. FISH analysis showed microdeletions in all of the nine cases studied. This study has accomplished two important findings ie. while the FISH method is mandatory in ruling out microdeletion syndromes, conventional cytogenetics acts as a screening tool in revealing other chromosomal abnormalities that may be involved with the disease.
The Role of Conventional and Molecular Cytogenetics in the Diagnosis of Microdeletion Syndromes
Author
Abstrak
Kajian ini bertujuan untuk menunjukkan peranan kaedah hibridisasi in situ pendaflor (FISH) dan sitogenetik konvensional (karyotip) pada kes sindrom mikrodelesi yang telah disahkan secara sitogenetik dan klinikal. Sejumlah sembilan kes telah dirujuk dari tahun 2002 hingga 2004 di Unit Sitogenetik, Hospital Universiti Kebangsaan Malaysia (HUKM). Kes-kes tersebut terdiri daripada tiga sindrom Prader-Willi, tiga sindrom DiGeorge, satu sindrom Williams , satu sindrom Miller-Dieker dan satu sindrom Kallmann. Sampel darah kesemua pesakit telah dikultur dan dituai mengikut prosedur standard. Sebanyak 20 serakan metafasa telah dianalisa untuk setiap kes. Analisa FISH dilakukan untuk kesemua kes menggunakan prob komersial (Vysis,USA): SNRPN dan D15S10 untuk sindrom Prader-Willi, LIS1 untuk sindrom Miller-Dieker, ELN untuk sindrom Williams, KAL untuk sindrom Kallmann, TUPLE1 dan D22S75 untuk sindrom DiGeorge. Analisa sitogenetik konvensional menunjukkan kariotip normal untuk kesemua kes kecuali satu yang menunjukkan aberasi kromosom melibatkan kromosom 9 dan 22. Analisa FISH menunjukkan mikrodelesi pada kesemua sembilan kes. Kajian ini menunjukkan dua fakta penting, iaitu hibridisasi in situ pendaflor (FISH) merupakan kaedah yang mesti dilakukan untuk pengecaman sindrom mikrodelesi, manakala kaedah sitogenetik konvensional merupakan kaedah saringan bagi keabnormalan kromosom yang mungkin berkaitan dengan penyakit tersebut.
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Related Images
 table1.jpg "TABLE 1: Results of Conventional and FISH analysis using locus specific probe of the nine cases studied")
 image1.jpg "FIGURE 1: Giemsa-banded chromosomes showing the karyotype of the patient with DiGeorge syndrome (case 9). The whole of the long arm of chromosome 22 is translocated onto the short arm of chromosome 9, resulting in monosomy of chromosome 22 (bottom arrow).")
 image2.jpg "FIGURE 2: Interphase and metaphase spreads hybridised with LSI DiGeorge TUPLE 1 region probe. Absence of the red signal on one of the chromosome 22 indicates deletion of the locus at 22q11.2.")
 image3.jpg "FIGURE 3: Giemsa-banded chromosomes showing karyotype of patient’s (Case 9) mother with translocation between the long arm of chromosome 22 and the short arm of chromosome 9 (arrows).")
