kjlm The Korean Journal of Laboratory Medicine Korean J Lab Med 2383-5702 2383-5710 The Korean Society for Laboratory Medicine 10.3343/kjlm.2009.29.1.71 kjlm-29-71 Original Article Comparing Two Diagnostic Laboratory Tests for Several Microdeletions Causing Mental Retardation Syndromes: Multiplex Ligation-Dependent Amplification vs Fluorescent In Situ Hybridization ChoEun HaeM.D. ParkBo Ya NaM.S. ChoJung HeeM.T. KangYou SunM.T. Greencross Reference Laboratory, Yongin, Korea Corresponding author: Eun Hae Cho, M.D. Greencross Reference Laboratory, 314 Bojeong-dong, Giheung-gu, Yongin 449-913, Korea Tel: +82-31-260-9216, Fax: +82-31-260-9638 E-mail: ehcho@mail.gcrl.co.kr 022009 14022009 291 7176 18082008 28112008 01122008 Copyright © 2009 by the Korean Society for Laboratory Medicine 2009 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Background

Microdeletion syndromes not detectable by conventional cytogenetic analysis have been reported to occur in approximately 5% of patients with unexplained mental retardation (MR). Therefore, it is essential to ensure that patients with MR are screened for these microdeletion syndromes. Mental retardation syndrome multiplex ligation-dependent probe amplification (MRS-MLPA) is a new technique for measuring sequence dosages that allows for the detection of copy number changes of several microdeletion syndromes (1p36 deletion syndrome, Williams syndrome, Smith-Magenis syndrome, Miller-Dieker syndrome, DiGeorge syndrome, Prader-Willi/Angelman syndrome, Alagille syndrome, Saethre-Chotzen syndrome, and Sotos syndrome) to be processed simultaneously, thus significantly reducing the amount of laboratory work.

 Methods

We assessed the performance of MLPA (MRC-Holland, The Netherlands) for the detection of microdeletion syndromes by comparing the results with those generated using FISH assays. MLPA analysis was carried out on 12 patients with microdeletion confirmed by FISH (three DiGeorge syndrome, four Williams syndrome, four Prader-Willi syndrome, and one Miller-Dieker syndrome).

 Results

The results of MLPA analysis showed a complete concordance with FISH in 12 patients with microdeletion syndromes.

 Conclusions

On the basis of these results, we conclude that MLPA is an accurate, reliable, and cost-effective alternative to FISH in the screening for microdeletion syndromes.

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The positions of FISH probes compared to MLPA probes. (A) DiGeorge syndrome, (B) Williams syndrome, (C) Prader-Willi/Angelman syndrome, (D) Miller-Dieker syndrome.

Abbreviation: MLPA, multiplex ligand-dependent probe amplification.

MLPA results were analyzed employing Genemarker version 1.6 software. The red dot indicates a probe of peak ratio less than 0.75 compared with normal control. The green dot indicates a probe of peak ratio 0.75-1.3 compared with normal control. (A) MLPA results of a patient with DiGeorge syndrome showed the deletions in five probes for CTCL1, CDC45L, CLDN5, ARVCF, and FLJ14360 genes. (B) MLPA results of normal control. (C) MLPA results of a patient with Prader-Willi/Angelman syndrome showed the deletions in five probes of MKRN3, NDN, UBE3A, and GABRB3 genes. (D) MLPA results of a patient with Williams syndrome showed the deletions in six probes of FZD9, STX1A, ELN, LIMK1, and CYLN2 genes. (E) MLPA results of normal control. (F) MLPA results of Miller-Dieker syndrome showed the deletions in seven probes of HIC1, METT10D, PAFAH1B1, ASPA, and TRPV1 genes. (G) MLPA dosage histograms of Williams syndrome.

Abbreviation: MLPA, multiplex ligation-dependent probe amplification.

Characteristics of MLPA probes used for detection of several microdeletion syndromes

Microdeletion syndrome Chromosomal position No. of probes Target genes
1p36 deletion syndrome 1p36.33 7 TNFRSF18, TNFRSF4, SCNN1D, GNB1, SKI, FLJ10782, TP73
Williams syndrome 7q11.23 6 FZD9, STX1A, ELN, LIMK1, CYLN2
Smith-Magenis syndrome 17p11.2 5 TACI/TNFRSF13B, LRRC48, LLGL1, PRPSAP2, MFAP4
Miller-Dieker syndrome 17p13.3 7 HIC1, METT10D, PAFAH1B1, ASPA, TRPV1
DiGeorge syndrome 22q11.21 6 CTCL1, CDC45L, CLDN5, ARVCF, FLJ14360, SNAP29
Prader-Willi/Angelman syndrome 15q11.2 5 MKRN3, NDN, UBE3A, GABRB3
Alagille syndrome 20p12.2 2 JAG1
Saethre-Chotzen syndrome 7p21.2 2 TWIST, TWISTNB
Sotos syndrome 5q35.3 3 NSD1 exon4, NSD1 exon12, NSD1 exon 17