Multiplex Ligation-Dependent Probe Amplification for Rapid Detection of Proteolipid Protein 1 Gene Duplications and Deletions in Affected Males and Carrier Females with Pelizaeus–Merzbacher Disease

Abstract

Background: Pelizaeus-Merzbacher disease is a rare X-linked neurodegenerative disorder caused by sequence variations in the proteolipid protein 1 gene (PLP1). PLP1 gene duplications account for ϳ50%-75% of cases and point variations for ϳ15%-20% of cases; deletions and insertions occur infrequently. We used multiplex ligation-dependent probe amplification (MLPA) to detect PLP1 gene alterations, especially gene duplications and deletions. Methods: We performed MLPA on 102 samples from individuals with diverse PLP1 gene abnormalities and from controls, including 50 samples previously characterized for the PLP1 gene by quantitative PCR but which were anonymized for prior results and sex. Results: All males with PLP1 gene duplications (n ‫؍‬ 13), 1 male with a triplication, 2 males with whole gene deletions, and all controls (n ‫؍‬ 72) were unambiguously assigned to their correct genotype. Of 4 female carriers tested by MLPA and quantitative PCR, 3 were duplication carriers by both methods, and 1 was a triplication

Reduced PLP1 expression in induced pluripotent stem cells derived from a Pelizaeus–Merzbacher disease patient with a partial PLP1 duplication

“…Although there have been reports PLP1 expression in disease-specific iPS cells K Shimojima et al of partial deletions in PLP1 identified by multiplex ligation-dependent probe amplification analysis, 9 this is the first report of a partial duplication of PLP1. The duplicated segment included the promoter region and the first three exons.…”

“…Initial screening for PLP1 duplication was performed by multiplex ligation-dependent probe amplification analysis by using the PLP1 Kit (P022; MRC-Holland, Amsterdam, The Netherlands) according to the manufacturer's instruction. 9 In case of PLP1 duplication, the aberration region was confirmed by microarray-based comparative genomic hybridization (aCGH) using the Agilent Human 105A CGH Kit (Agilent Technologies, Santa Clara, CA, USA) as described previously. 8 To detect the small duplication in Patient 1, a custom array was designed using e-array, a web-based software (https://earray.chem.agilent.com/earray/), and 29 918 probes in chrX:98 000 000-104 500 000, around PLP1, were selected.…”

“…9 Patient 2 had a duplication of all 7 exons of PLP1, and subsequent aCGH analysis by using the Human Genome CGH Microarray 105 K (Agilent Technologies) revealed that the duplicated region was chrX:102 519 000-103 155 851 (636 851 bp) with an average log 2 ratio of þ 0.83, which is a typical duplication region seen in PMD patients with PLP1 duplications (Figure 2a). The duplication was confirmed by fluorescence in-situ hybridization (Figure 2b), and the direction of the duplicated segment, including PLP1, was shown to be in a tandem configuration by fiber-fluorescence in-situ hybridization analysis (Figure 2c).…”

Unusual Presentation of Pelizaeus-Merzbacher Disease: Female Patient with Deletion of the Proteolipid Protein 1 Gene

“…After a review of the literature, we located 7 other cases of affected females with a genetic diagnosis of PMD in each case finding a mutation or duplication of the PLP1 gene [2–4]. Our patient was the first affected female with a gene deletion.…”

Magnetic resonance imaging and spectroscopic analysis in 5 cases of Pelizaeus-Merzbacher disease: metabolic abnormalities as diagnostic tools

“…The mechanism leading to the higher incidence of affected women most likely involves random X-inactivation and altered oligodendrocyte differentiation and survival that depends on the severity of the PLP1 mutation9). In the patients described in this report, molecular analysis of the PLP1 gene was conducted using MLPA, which is more accurate than fluorescence in situ hybridization or quantitative polymerase chain reaction for determining PLP1 copy numbers10). Duplication of the PLP1 gene was detected in patients 1 and 3, both of whom were boys.…”