Clinical and mutational spectrum of Colombian patients with Pelizaeus Merzbacher Disease / Heterogeneidad clínica y mutacional en pacientes colombianos con Pelizaeus Merzbacher

Abstract Case Presentation: Pelizaeus Merzbacher Disease (PMD) is an X-linked developmental defect of myelination that causes childhood chronic spastic encephalopathy. Its genetic etiology can be either a duplication (or other gene dosage alterations) or a punctual mutation at the PLP1 locus. Clinically, it presents with developmental delay, nystagmus and, spasticity, supported by neuroimaging in which the defect of myelination is evident. We present a series of seven Colombian patients diagnosed with this leucodystrophy, describing their genotypic and phenotypic characteristics and heterogeneity. Clinical Findings: All patients included were male, 6 months to 16 years of age. Mean age at onset of symptoms was 8 months. Mean age at diagnosis was 5 years 5 months, being classic PMD most frequently diagnosed, as compared to the connatal phenotype. All cases had a primary diagnosis of developmental delay on 100%, and in 28.7% of cases, early onset nystagmus was described. 85.7% of patients had spasticity, 71.4% cerebellar signs, 57.0% hypotonia, and 28.5% had an abnormal movement disorder. Only three patients were able to achieve gait, though altered. In the two patients who had a diagnosis of connatal PMD maturational ages in danger zones according to the WHO Abbreviated Scale of Psychosocial Development were documented. All cases had abnormalities in neuroimages. Molecular Analysis and Results: Molecular studies were used in the majority of the cases to confirm the diagnosis (85.7 %). For two cases molecular confirmation was not considered necessary given their affected male brothers had already been tested. PLP1 gene dosage alterations (duplications) were found in 28.5 % of the patients (two siblings), whereas three different single nucleotide variants were detected. Clinical Relevance: According to these findings, as authors we propose the diagnostic algorithm in Colombian population to begin on a high clinical suspicion, followed by paraclinical extension, moving on to the molecular confirmation by using approaches to simultaneously sequence the PLP1 gene in order to detect point mutations and in/dels and performing a copy number variation analysis for the detection of gene dosage alterations.

Resumen Descripción del caso: La enfermedad de Pelizaeus Merzbacher es una leucodistrofia ligada al X que causa encefalopatía espástica crónica en la infancia. Su etiología es genética, por duplicaciones u otros trastornos de la dosis génica o mutaciones puntuales del gen PLP1, lo que condiciona la formación anormal de las vainas de mielina principalmente en el sistema nervioso central. Clínicamente se caracteriza por un cuadro de retardo del neurodesarrollo, nistagmus y espasticidad, con neuroimágenes que evidencian la dismielinización. Presentamos una serie de siete casos colombianos con esta leucodistrofica en la que describimos fenotípica y genotípicamente la heterogeneidad de esta enfermedad en nuestra población. Hallazgos clínicos: Todos los pacientes analizados fueron de sexo masculino, con edad promedio de inicio de síntomas hacia los ocho meses de vida. La edad media al diagnóstico fue de 5 años 5 meses, siendo más frecuente el diagnóstico de PMD clásica que el tipo connatal. Se describe retardo del desarrollo motor en el 100% de los casos, acompañado de nistagmus en el 28.7%. 85.7% de los casos tenía algún grado de espasticidad, 71.4 % signos cerebelosos, 57.0% hipotonía, y hasta en 28.5% se evidenciaron movimientos anormales. Solo tres pacientes lograron marcha, aunque patológica. En los dos pacientes con la forma connatal se documentó una edad maduracional motora en el rango de Alerta, de acuerdo a la escala abreviada del desarrollo de la OMS. En todos los casos se detectó algún tipo de anormalidad en el estudio imagenológico cerebral. Estudios Moleculares y Resultados: El diagnóstico molecular se empleó en la mayoría de los casos (85.7%), encontrando alteraciones en la dosis génica en el 28.5% y tres diferentes mutaciones puntuales. Relevancia clínica: Dados los hallazgos en los resultados del estudio molecular, sugerimos que en el abordaje diagnóstico confirmatorio para la población colombiana se debería contemplar en un mismo tiempo tanto la secuenciación como el estudio de variantes del número de copias del gen afectado, contrario a lo sugerido en literatura mundial en la que se inicia con estudio para duplicación / deleción.

AATYK is a Novel Regulator of Oligodendrocyte Differentiation and Myelination / 神经科学通报·英文版

Oligodendrocytes (OLs) are myelinating glial cells that form myelin sheaths around axons to ensure rapid and focal conduction of action potentials. Here, we found that an axonal outgrowth regulatory molecule, AATYK (apoptosis-associated tyrosine kinase), was up-regulated with OL differentiation and remyelination. We therefore studied its role in OL differentiation. The results showed that AATYK knockdown inhibited OL differentiation and the expression of myelin genes in vitro. Moreover, AATYK-deficiency maintained the proliferation status of OLs but did not affect their survival. Thus, AATYK is essential for the differentiation of OLs.

In silico perspectives on the prediction of the PLP's epitopes involved in multiple sclerosis

Background: Multiple sclerosis [MS] is the most common autoimmune disease of the central nervous system [CNS]. The main cause of the MS is yet to be revealed, but the most probable theory is based on the molecular mimicry that concludes some infections in the activation of T cells against brain auto-antigens that initiate the disease cascade

Objectives: The Purpose of this research is the prediction of the auto-antigen potency of the myelin proteolipid protein [PLP] in multiple sclerosis

Materials and Methods: As there wasn't any tertiary structure of PLP available in the Protein Data Bank [PDB] and in order to characterize the structural properties of the protein, we modeled this protein using prediction servers. Meta prediction method, as a new perspective in silico, was performed to find PLPs epitopes. For this purpose, several T cell epitope prediction web servers were used to predict PLPs epitopes against Human Leukocyte Antigens [HLA]. The overlap regions, as were predicted by most web servers were selected as immunogenic epitopes and were subjected to the BLASTP against microorganisms

Results: Three common regions, AA[58-74], AA[161-177], and AA[238-254] were detected as immunodominant regions through meta-prediction. Investigating peptides with more than 50% similarity to that of candidate epitope AA[58-74] in bacteria showed a similar peptide in bacteria [mainly consistent with that of clostridium and mycobacterium] and spike protein of Alphacoronavirus 1, Canine coronavirus, and Feline coronavirus. These results suggest that cross reaction of the immune system to PLP may have originated from a bacteria or viral infection, and therefore molecular mimicry might have an important role in the progression of MS

Conclusions: Through reliable and accurate prediction of the consensus epitopes, it is not necessary to synthesize all PLP fragments and examine their immunogenicity experimentally [in vitro]. In this study, the best encephalitogenic antigens were predicted based on bioinformatics tools that may provide reliable results for researches in a shorter time and at a lower cost

Ethanol down regulates the expression of myelin proteolipid protein in the rat hippocampus / 대한해부학회지

It is well known that chronic ethanol treatment affects the synthesis of RNA and protein in the brain and the maintenance and function of nervous system. The changes in myelination-related genes are most prominent in human alcoholics. Previously, our cDNA microarray study showed altered Proteolipid protein (PLP), a major protein of central myelin. The present study aimed to gain more understanding of the expression of PLP after chronic ethanol treatment. Male Sprague-Dawley rats were daily treated with ethanol (15% in saline, 3 g/kg, i.p.) or saline for 14 days. Messenger RNAs from hippocampus of each group were subjected to cDNA expression array hybridization to determine the differential gene expressions. Among many ethanol responsive genes, PLP was negatively regulated by ethanol treatment, which is one of the most abundant proteins in the CNS and has an important role in the stabilization of myelin sheath. Using northern blot and immunohistochemical analysis, we showed the change in expression level of PLP mRNA and protein after ethanol treatment. PLP mRNA and protein were decreased in hippocampus of rat with chronic ethanol exposure, suggesting that ethanol may affect the stabilization of myelin sheath through the modulation of PLP expression and induce the pathophysiology of alcoholic brain.

Identification of Proteolipid Protein 1 Gene Duplication by Multiplex Ligation-Dependent Probe Amplification: First Report of Genetically Confirmed Family of Pelizaeus-Merzbacher Disease in Korea

Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive disorder with a prototype of a dysmyelinating leukodystrophy that is caused by a mutation in the proteolipid protein 1 (PLP1) gene on the long arm of the X chromosome in band Xq22. This mutation results in abnormal expression or production of PLP. We here present a Korean boy with spastic quadriplegia, horizontal nystagmus, saccadic gaze, intentional tremor, head titubation, ataxia, and developmental delay. The brain magnetic resonance imaging (MRI) showed abnormally high signal intensities in the white matter tract, including a subcortical U fiber on the T2-weighted and fluid attenuated inversion recovery (FLAIR) image. The chromosomal analysis was normal; however, duplication of the PLP1 gene in chromosome Xq22 was detected when the multiplex ligation-dependent probe amplification (MLPA) method was used. We also investigated the pedigree for a genetic study related to PMD. This case suggests that the duplication mutation of the PLP1 gene in patients with PMD results in a mild clinical form of the disorder that mimics the spastic quadriplegia of cerebral palsy.

Proteolipid protein 1 gene mutation in nine patients with Pelizaeus-Merzbacher disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive disorder with symptoms including nystagmus, impaired motor development, ataxia, and progressive spasticity. The proteolipid protein 1 (PLP1) gene is the only pathogenic gene of PMD. Duplication of the PLP1 gene is the most frequent gene defect, accounting for 50%-70% of PMD cases, whereas point mutations in the coding sequence or the splice sites account for 10%-25% of PMD cases. This study aimed to identify PLP1 mutations in nine unrelated Chinese patients (P1-9) with PMD, and 14 subjects from the family of patient 2 were also described.</p><p><b>METHODS</b>Genomic DNA was extracted from peripheral blood samples. Gene dosage was determined using the multiplex ligation-dependent probe amplification (MLPA). All 7 exons and exon-intron boundaries of the PLP1 gene were amplified and analyzed using direct DNA sequencing.</p><p><b>RESULTS</b>Of these nine patients, there were four transitional, four classical, and one connatal PMD according to their clinical and radiological presentations. PLP1 duplications were identified in patients 1-7 with PMD. Their mothers were PLP1 duplications carriers as well. Both duplication carriers and normal genotypes of PLP1 were identified in the family members of patient 2. A c.517C > T (p. P173S) hemizygous missense mutation in exon 4 was found in patient 8 with PMD, and his mother was shown to be a heterozygote of this mutation.</p><p><b>CONCLUSIONS</b>We identified seven genomic duplications and one missense mutation (p. P173S) of the PLP1 gene in eight Chinese patients with PMD. This is the report about PLP1 mutations in PMD patients from the mainland of China.</p>

Clinical and genetic analysis of a family with Pelizaeus-Merzbacher disease / 中华儿科杂志

<p><b>OBJECTIVE</b>Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive leukoencephalopathy. Few reports of PMD patients without genetic confirmation have been published in the mainland of China. The clinical and genetic features of a family with PMD were analyzed, which may contribute to definite diagnosis, genetic counseling and prenatal diagnosis of this rare hereditary disease in China.</p><p><b>METHODS</b>Clinical data of the proband and other family members as well as 14 DNA samples were collected. Clinical features including symptoms, signs and cranial MRI were analyzed. Multiplex ligation-dependent probe amplification (MLPA) assays were performed to detect PLP1 duplication, which helps identify the type of PLP1 mutation in this family and the genotype-phenotype correlations.</p><p><b>RESULTS</b>(1) The proband and the other 3 male patients in the family presented with nystagmus, motor retardation followed by regression. The cranial MRI of proband showed evidence of poor myelination with diffused high signal in white matter region on T2-weighed image and reduced amount of white matter in volume, which is consistent with the typical features of cranial MRI in PMD. (2) PLP1duplication was identified in the proband. Combined with the clinical features of the proband and other patients in this family, the diagnosis of classic form of PMD was confirmed. Another 3 females with normal phenotype in the family were proved to be carriers of PLP1duplication.</p><p><b>CONCLUSIONS</b>(1) The Classic form of PMD in this pedigree is resulted from the PLP1 duplication, which is consistent with the previously reported genotype-phenotype correlations; (2) The results serve as an evidence for reliable genetic counseling and prenatal diagnosis for this family. (3) MLPA, which is a newly developed method, is a rapid and reliable technique to detect the whole gene duplication of PLP1.</p>

Combined therapy of methylprednisolone and brain-derived neurotrophic factor promotes axonal regeneration and functional recovery after spinal cord injury in rats / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the effects of combination therapy with methylprednisolone (MP) and brain-derived neurotrophic factor (BDNF) on axonal remyelination and functional recovery after spinal cord injury in rats.</p><p><b>METHODS</b>Forty-five rats were randomly divided into three groups: Group A received MP and BDNF; group B received MP and cerebrospinal fluid (CSF); and group C received CSF only. Contusion injury to adult rat spinal cord was produced at the T(10) vertebra level followed by immediate intravenous MP or CSF, and was thereafter infused intrathecally with BDNF or CSF for 6 weeks. Axonal remyelination and functional recovery was observed using RT-PCR, immunohistochemistry and open field locomotion.</p><p><b>RESULTS</b>An increase of 28.4% +/- 2.3% in the expression of proteolipid protein (PLP) gene, an endogenous indicator of axonal remyelination, was demonstrated in group A 24 hours after injury. Ten weeks later, there were significant decreases in hematogenous inflammatory cellular infiltration in groups A and B compared to C (P < 0.05). Concomitantly, a significant amount of axonal remyelination was observed in group A compared to groups B and C (P < 0.05). Furthermore, combination therapy using MP and BDNF in group A resulted in stimulation of hindlimb activity as well as improvement in the rate of functional recovery in open field locomotion (P < 0.05).</p><p><b>CONCLUSIONS</b>Combined therapy of MP and BDNF can improve functional recovery through mechanisms that include attenuating inflammatory cellular infiltration and enhancing axonal remyelination at the injury site. Such a combination may be an effective approach for treatment of spinal cord injury.</p>

Characterization of proteolipid protein-peptide-specific CD(4)(+) T cell of experimental allergic encephalomyelitis in Biozzi AB/H mice / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To detect the function of proteolipid protein (PLP) peptide (residues 56 - 70)-specific CD(4)(+) T cells in experimental allergic encephalomyelitis (EAE) in Biozzi AB/H mice (H-2A(g7)).</p><p><b>METHODS</b>Biozzi AB/H mice were immunized by synthetic PLP(56 - 70) peptide (DYEYLINVIHAFQYV) which was emulsified by sonication with complete Freund's adjuvant, a EAE model proven histologically and clinically. Murine splenocytes and spinal cord infiltrated (SCI) T cells were stimulated by PLP(56 - 70), then the CD(4)(+) T cells were isolated by Dynabeads, and confirmed by staining with anti-CD(4) antibody. Finally, the IL2 bioassay and IFN-gamma/IL4 ELISA were done to detect T cell proliferation and cytokine secretion after PLP(56 - 70) stimulation.</p><p><b>RESULTS</b>The histology of murine spinal cord showed a great number of lymphocytes infiltrated the spinal cord; the clinical signs showed high scores (4.3) on the peak, as well as a good EAE model. After being isolated by Dynabeads, CD(4)(+) T cells showed high purification (> 99%) by staining with anti-CD(4) antibody. IL2 bioassay showed that those T cells were PLP(56 - 70)-specific T cells. ELISA showed that those T cells had high IFN-gamma/IL4 ratio, indicating that they are T helper 1 (Th1) cells.</p><p><b>CONCLUSIONS</b>PLP(56 - 70)-specific splenocytes and SCI CD(4)(+) T cells in EAE from Biozzi AB/H mice were detected and showed that both of them were PLP(56 - 70)-specific Th1 cells. It is beneficial to understand what kind of role these T cells play in the development of EAE.</p>

Identification of sequence similarities between Mycobacterium leprae and the myelin proteolipid protein by computational analysis.

This study was undertaken under the assumption that antigenic mimicry plays a role in the pathogenesis of neuropathy in leprosy, a unique feature among mycobacterial diseases. The SWISS-PROT protein sequence databank was scanned using a computer programme based on an identity matrix algorithm, to identify common amino acid regions between human myelin and mycobacterial proteins. The highlighted motifs were back-tested against a database of MHC-binding peptides (MHCPEP). Of the 28 common sequences between mycobacterial and human myelin proteins, only two were found to yield some matches with MHC-presenting peptides. Both motifs were from M.leprae. The myelin proteolipid protein was the human protein containing the identified similarities. We believe that this theoretical approach can provide a way to predict potentially "mimetic" motifs by search for antigenic regions in protein sequence databases without screening a large number of synthetic peptides.