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Abstract
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).
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Fig. 1.
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.
Fig. 2.
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.
Table 1.
Characteristics of MLPA probes used for detection of several microdeletion syndromes
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