A Specific Diplotype H1j/H2 of the MAPT Gene Could Be Responsible for Parkinson’s Disease with DementiaRead the full article
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A Specific Diplotype H1j/H2 of the MAPT Gene Could Be Responsible for Parkinson’s Disease with Dementia
Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease. Five to ten percent of patients have monogenic form of the disease, while most of sporadic PD cases are caused by the combination of genetic and environmental factors. Microtubule-associated protein tau (MAPT) has been appointed as one of the most important risk factors for several neurodegenerative diseases including PD. MAPT is characterized by an inversion in chromosome 17 resulting in two distinct haplotypes H1 and H2. Studies described a significant association of MAPT H1j subhaplotype with PD risk, while H2 haplotype was associated with Parkinsonism, particularly to its bradykinetic component. We report here an isolated case displaying an akinetic-rigid form of PD, with age of onset of 41 years and a good response to levodopa, who developed dementia gradually during the seven years of disease progression. The patient does not carry the LRRK2 G2019S mutation, copy number variations, nor pathogenic and rare variants in known genes associated with PD. MAPT subhaplotype genotyping revealed that the patient has the H1j/H2 diplotype, his mother H1j/H1j, his two healthy brothers H1j/H1v and his deceased father was by deduction H1v/H2. The H1j/H2 diplotype was shown in a total of 3 PD patients among 80, who also did not have known PD-causing mutation and in 1 out of 92 healthy individual controls. The three patients with this diplotype all have a similar clinical phenotype. Our results suggest that haplotypes H1j and H2 are strong risk factor alleles, and their combination could be responsible for early onset of PD with dementia.
Cytogenomic Abnormalities in 19 Cases of Salivary Gland Tumors of Parotid Gland Origin
Salivary gland tumors (SGTs) of parotid origin are a group of diverse neoplasms which are difficult to classify due to their rarity and similar morphologic patterns. Chromosome analysis can detect clonal abnormalities, and array comparative genomic hybridization (aCGH) analysis can define copy number alterations (CNAs) from tumor specimens. Of the 19 cases of various types of SGTs submitted for cytogenomic analyses, an abnormal clone was detected in nine cases (47%), and CNAs were detected in 14 cases (74%). Recurrent rearrangements involving the PLAG1 gene at 8q12, recurrent CNAs including deletions of 6q, 9p (CDKN2A), and 17p (TP53), loss of Y chromosome, and gain of chromosome 7 were defined from these cases. Combined karyotyping and aCGH analyses could improve diagnostic yield. Future study for more precisive correlation of SGT classification with cytogenomic abnormalities will facilitate better diagnosis and treatment.
Multimodal Imaging Characteristics of ADRP in a Family with p.Thr58Arg Substituted RHO Mutation
Background. Autosomal dominant retinitis pigmentosa (adRP) is a rare cause of progressive visual impairment in young patients and is frequently a result of RHO gene mutations. p.Thr58Arg rhodopsin mutation leads to misfolding of rhodopsin, subsequent accumulation in the endoplasmic reticulum, and leads to consecutive atrophy of photoreceptor cells through apoptosis. Materials and Methods. We describe multimodal imaging findings in a 58-year-old female with adRP due to a c.173 C > G, p.Thr58Arg rhodopsin mutation (confirmed on genotyping), including ultra-wide-field fundus autofluorescence (UWF-FAF), color scanning laser ophthalmoscopy, structural optical coherence tomography (OCT), OCT-angiography (OCT-A), electroretinography (ERG), and visual field testing (HVF). Additionally, we compare the patient’s phenotypic findings to those of her offspring, who was also affected by adRP. Results. The 58-year-old female and her son with symptoms of nyctalopia and decreased vision showed macular pigmentary changes in a bull’s-eye pattern along with bone spicules in periphery with retinal atrophy. Genotyping confirmed p.Thr58Arg rhodopsin mutation. Wide area of dystrophic retina was noted on UWF-FAF, along with corresponding atrophy of photoreceptor layer on OCT. OCTA revealed complete nonperfusion of the superficial capillary plexus in areas of retinal dystrophy. ERG revealed increased latency and decreased amplitudes; HVF revealed constriction of visual fields consistent with retinal findings. Conclusions. Multimodal imaging is extremely helpful in delineating the extent of retinal dystrophy and comparable to ERG for monitoring of progress in retinitis pigmentosa. Photoreceptor layer thickness (measured with OCT) strongly correlated with ERG and can be used as a secondary surrogate for monitoring the disease progress.
Genetic Testing Distinguishes Multiple Chondroid Chordomas with Neuraxial Bone Metastases from Multicentric Tumors
Background. Chordomas are rare malignant bone tumors preferentially forming in neuraxial bones. Chondroid chordoma is a subtype of chordoma. Chordomas reportedly present as synchronous multiple lesions upon initial diagnosis. However, it remains unknown whether these lesions are multicentric or metastatic multiple chordoma tumors. Case Presentation. Here, we present the case of a 57-year-old woman with multiple chordomas at the clivus, C6, and T12 upon initial presentation. Sequential surgeries and radiotherapy were performed for these lesions, and postoperative histological diagnosis revealed that all lesions were chondroid chordomas. Next-generation sequencing revealed that these lesions harbored a common somatic mutation in epidermal growth factor receptor (EGFR), c.3617A>C, which is not considered a pathogenic chordoma mutation, thus indicating that these lesions were not multicentric but rather multiple metastatic tumors. Subsequent multiple metastases to the lung and appendicular and axial bones were detected 15 months after the initial surgery. Recurrent lesions at the clivus progressed despite EGFR-targeted therapy, surgery, and radiotherapy. Conclusion. The present evidence indicates that multiple chordomas in this case were caused by multiple metastases rather than multicentric lesions. Multiple presentations of chordoma imply systemic dissemination of tumor cells, and novel efficient systemic therapy is required to treat this disease.
Hyperkalemic Periodic Paralysis: Case Report with a SCNA4 Gene Mutation and Literature Review
Hyperkalemic periodic paralysis is a rare musculoskeletal disorder characterized by episodic muscle weakness associated with hyperkalemia. It is a channelopathy associated with point mutations in the SCNA4 gene, with an autosomal dominant pattern of inheritance. We report the case of a 39-year-old patient with a picture with onset at six years of age, consisting of episodes of weakness caused by physical activity and intercurrent infectious processes, in whom a point mutation was found in the SCNA4 gene, not previously reported in the literature.
Acute Intermittent Porphyria in a Man with Dual Enzyme Deficiencies
Porphyrias are a heterogeneous group of metabolic disorders that result from the altered activity of specific enzymes of the heme biosynthetic pathway and are characterized by accumulation of pathway intermediates. Porphyria cutanea tarda (PCT) is the most common porphyria and is due to deficient activity of uroporphyrinogen decarboxylase (UROD). Acute intermittent porphyria (AIP) is the most common of the acute hepatic porphyrias, caused by decreased activity of hydroxymethylbilane synthase (HMBS). An Argentinean man with a family history of PCT who carried the UROD variant c.10_11insA suffered severe abdominal pain. Biochemical testing was consistent with AIP, and molecular analysis of HMBS revealed a de novo variant: c.344 + 2_ + 5delTAAG. This is one of the few cases of porphyria identified with both UROD and HMBS mutations and the first confirmed case of porphyria with dual enzyme deficiencies in Argentina.