Clinical and genetic analysis of Korean patients with congenital insensitivity to pain with anhidrosis

Congenital insensitivity to pain with anhidrosis (CIPA) is a rare autosomal recessive disease characterized by anhidrosis, insensitivity to noxious stimuli, and mental retardation. Mutations in the NTRK1 gene are associated with the pathogenesis of CIPA. In this study, we performed a clinical and genetic analysis on the NTRK1 gene in four Korean patients with CIPA. All patients had typical clinical manifestations of CIPA, including anhidrosis, recurrent fever, absent pain perception, and developmental delay. Sequencing analysis revealed one predominant mutation, c.851‐33T>A, in four affected alleles and three novel mutations, including c.287+2dupT, c.2155G>A (p.Glu719Lys), and c.1218delC (p.Pro407ArgfsX), in each affected allele. For one patient, who was heterozygous for c.851‐33T>A, another mutation could not be identified, suggesting that a possible hidden intronic or large genomic mutation may have been present. This study extends the spectrum of mutations in the NTRK1 gene and confirms that Korean patients with CIPA have the same genetic background as other ethnicities. Muscle Nerve, 2009     

Novel NTRK1 mutations associated with congenital insensitivity to pain with anhidrosis verified by functional studies

Congenital insensitivity to pain with anhidrosis (CIPA), also known as hereditary sensory and autonomic neuropathy type IV, features loss of pain sensation, decreased or absent sweating (anhidrosis), recurrent episodes of unexplained fever, self‐mutilating behavior, and variable mental retardation. Mutations in neurotrophic receptor tyrosine kinase 1 (NTRK1) have been reported to be associated with CIPA. We identified four novel NTRK1 mutations in six Korean patients from four unrelated families. Of the four mutations, we demonstrated using a splicing assay that IVS14+3A>T causes aberrant splicing of NTRK1 mRNA, leading to introduction of a premature termination codon. An NTRK1 autophosphorylation assay showed that c.1786G>A (p.Asp596Asn) abolished autophosphorylation of NTRK1. In addition, Western blotting showed that c.704C>G (p.Ser235*) and c.2350_2363del (p.Leu784Serfs*79) blunted NTRK1 expression to undetectable levels. The four novel NTRK1 mutations we report here will expand the repertoire of NTRK1 mutations in CIPA patients, and further our understanding of CIPA pathogenesis.     

Genetic analysis of the fused in sarcoma gene in Chinese Han patients with Parkinson's disease

Background and purposeExome sequencing in a large essential tremor (ET) family identified a novel nonsense mutation (p.Q290X) in the fused in sarcoma gene (FUS) as the cause of this family. Because of the clinical overlap between ET and Parkinson's disease (PD), the role of FUS in an independent cohort of PD patients from China mainland was evaluated.MethodsThe entire coding region of FUS in 508 Chinese Han patients with PD and the identified variants in 633 normal controls were evaluated. A variant was further screened in an additional 382 controls for the frequency in our population.ResultsA novel variant c.696C > T (p.Y232Y) in 2 sporadic patients with PD and six variants (c.52C > A, p.P18T; c.52C > T, p.P18S; c.147C > A, p.G49G; c.291C > T, p.Y97Y; c.684C > T, p.G228G; c.1176G > A, p.M392I) without significant difference in genotypic and allelic distributions in our PD cohort were identified.ConclusionThe FUS gene is not a genetic risk factor for PD in the population of Chinese Han ethnicity.     

POLR3A variants in striatal involvement without diffuse hypomyelination

BackgroundBiallelic variants in POLR3A encoding the largest subunit of RNA polymerase III cause POLR3-related (or 4H) leukodystrophy characterized by neurologic dysfunction, abnormal dentition, endocrine abnormalities and ocular abnormality. Recently, whole-exome sequencing enabled the discovery of POLR3A variants in cases lacking diffuse hypomyelination, the principal MRI phenotype of POLR3-related leukodystrophy. Homozygous c.1771-6C > G variants in POLR3A were recently suggested to cause striatal and red nucleus involvement without white matter involvement.Case report: Here, we report three cases in two families with biallelic POLR3A variants. We identified two sets of compound heterozygous variants in POLR3A, c.1771-6C > G and c.791C > T, p.(Pro264Leu) for family 1 and c.1771-6C > G and c.2671C > T, p.(Arg891*) for family 2. Both families had the c.1771-6C > G variant, which led to aberrant mRNA splicing. Neuropsychiatric regression and severe intellectual disability were identified in three patients. Two cases showed dystonia and oligodontia. Notably, characteristic bilateral symmetric atrophy and abnormal signal of the striatum without diffuse white matter signal change were observed in brain MRI of all three individuals.ConclusionsStriatum abnormalities may be another distinctive MRI finding associated with POLR3A variants, especially in cases including c.1771-6C > G variants and our cases can expand the phenotypic spectrum of POLR3A-related disorders.     

Novel missense, insertion and deletion mutations in the neurotrophic tyrosine kinase receptor type 1 gene (NTRK1) associated with congenital insensitivity to pain with anhidrosis

Hereditary sensory and autonomic neuropathy type IV (HSAN IV) or congenital insensitivity to pain with anhidrosis (CIPA) is an autosomal-recessive disorder affecting the neurotrophin signal transduction pathway. HSAN IV is characterized by absence of reaction to noxious stimuli, recurrent episodes of fever, anhidrosis, self mutilating behaviour and frequent mental retardation. Mutations in the neurotrophic tyrosine kinase receptor type 1 (NTRK1) are associated with this disorder. We investigated NTRK1 mutations in five HSAN IV patients and one less typical patient with hypohidrosis, insensitivity to pain as well as motor- and sensory deficits in the peripheral nervous system. For the HSAN IV patients we identified a homozygous missense mutation (p.I572S), a homozygous deletion of 1985bp (g.7335164-7336545del), a homozygous insertion c.722_723insC in exon 7 and two compound heterozygous mutations (p.Q558X+p.L717R). The less typical patient as well as one HSAN IV patient revealed no NTRK1 mutation.     

Distal spinal muscular atrophy featured by predominant calf muscle involvement in VRK1 associated disease – Case series and review

We describe the shared clinical, biochemical, radiological and myopathological characteristics of four patients with distal spinal muscular atrophy (dSMA) caused by vaccinia-related kinase 1 (VRK1) variants and provide a review of the literature on phenotype-genotype correlations in VRK1-related disease. The clinical phenotype was characterized by adult-onset dSMA with predominant calf muscle involvement and mildly elevated serum creatinine kinase (CK) levels. Muscle imaging showed predominant atrophy and fatty replacement of calf muscles. We identified the novel compound heterozygous variants c.607C>T (p.Arg203Trp) and c.858G>T (p.Met286Ile) in two siblings with adult-onset dSMA. Additionally, two unrelated patients both carried the known c.583T>G (p.Leu195Val) VRK1 variant, with either c.197C>G (p.Ala66Gly) or c.701A>G (p.Asn234Ser) as a second variant. We conclude that compound heterozygous VRK1 variants cause distal spinal muscular atrophy with predominant posterior leg muscle involvement.     

Novel frameshift and splice site mutations in the neurotrophic tyrosine kinase receptor type 1 gene (NTRK1) associated with hereditary sensory neuropathy type IV

Congenital insensitivity to pain with anhidrosis or hereditary sensory and autonomic neuropathy type IV (HSAN IV) is the first human genetic disorder implicated in the neurotrophin signal transduction pathway. HSAN IV is characterized by absence of reaction to noxious stimuli, recurrent episodes of fever, anhidrosis, self-mutilating behavior and often mental retardation. Mutations in the neurotrophic tyrosine kinase, receptor, type 1 (NTRK1) are associated with this disorder. Here we report four homozygous mutations, two frameshift (p.Gln626fsX6 and p.Gly181fsX58), one missense (p.Arg761Trp) and one splice site (c.359+5G>T) mutation in four HSAN IV patients. The splice site mutation caused skipping of exons 2 and 3 in patient's mRNA resulting in an in-frame deletion of the second leucine-rich motif. NTRK1 mutations are only rarely reported in the European population. This report extends the spectrum of NTRK1 mutations observed in patients diagnosed with HSAN IV.     

Novel variants in aromatic L-amino acid decarboxylase deficiency: Case report of sisters with mild phenotype

BackgroundAromatic L-amino acid decarboxylase (AADC) deficiency, caused by a pathogenic variant in the dopa decarboxylase (DDC) gene, is a rare neurometabolic disorder in which catecholamine and serotonin are not synthesized. From a large number of reports, it has been recognized that most affected patients show severe developmental delay in a bedridden state and are unable to speak. On the other hand, patients with a mild phenotype with AADC deficiency have been reported, but they number only a few cases. Therefore, the variation of phenotypes of the disease appears to be broad, and it may be challenging to diagnose an atypical phenotype as AADC deficiency.Case reportWe report novel compound heterozygous variants in DDC (c.202G > A and c.254C > T) in two sisters, whose main complaint was mild developmental delay, by whole-exome sequencing (WES). Additionally, we describe their clinical features and provide an image that shows the variants located at different sites responsible for the catalysis of AADC in a three-dimensional structure. The patients were prescribed a Monoamine oxidase (MAO) inhibitor after diagnosis.InterpretationOur cases indicate that a comprehensive genomic approach helps to diagnose AADC deficiency with atypical features, and underscore the significance of understanding the variations of this disorder for diagnosis and appropriate treatment.     

A case of CHOPS syndrome accompanied with moyamoya disease and systemic vasculopathy

BackgroundCHOPS syndrome, caused by a mutation in the AFF4 gene, is a recently established and extremely rare genetic disorder, which has moderate phenotypic overlap with Cornelia de Lange syndrome. The main phenotypes include characteristic facial features, short stature, obesity, skeletal and pulmonary involvement, and neurodevelopmental impairment.Case reportWe report on a Korean girl with CHOPS syndrome presenting with an atypical manifestation. The patient was referred to the out-patient clinic to evaluate the underlying etiology of short stature, obesity, developmental delay, and Moyamoya disease. The patient showed characteristic facial features including a round face, thick eyebrows, and synophrys. Her developmental milestones had been delayed since infancy and a moderate degree of intellectual disability persisted. She was also diagnosed with Moyamoya disease at 6 years of age and had undergone synangiosis surgery thrice. Her renal arteries and infrarenal aorta were diffusely narrowed. A novel de novo missense variant, c.758C > T (p.Pro253Leu) in AFF4 was identified by whole exome sequencing. No additional candidate variants for her vascular manifestation were found except a susceptibility variant, c.14429G > A (p.Arg4810Lys) in RNF213, inherited from asymptomatic mother.ConclusionThis is the first case of CHOPS syndrome accompanied by systemic vasculopathy. More clinical observations and functional studies are required to clarify this association.     

Recessive null-allele variants in MAG associated with spastic ataxia,nystagmus, neuropathy,and dystonia

IntroductionThe gene encoding myelin-associated glycoprotein (MAG) has been implicated in autosomal-recessive spastic paraplegia type 75. To date, only four families with biallelic missense variants in MAG have been reported. The genotypic and phenotypic spectrum of MAG-associated disease awaits further elucidation.MethodsFour unrelated patients with complex neurologic conditions underwent whole-exome sequencing within research or diagnostic settings. Following determination of the underlying genetic defects, in-depth phenotyping and literature review were performed.ResultsIn all case subjects, we detected ultra-rare homozygous or compound heterozygous variants in MAG. The observed nonsense (c.693C > A [p.Tyr231*], c.980G > A [p.Trp327*], c.1126C > T [p.Gln376*], and 1522C > T [p.Arg508*]) and frameshift (c.517_521dupAGCTG [p.Trp174*]) alleles were predicted to result in premature termination of protein translation. Affected patients presented with variable combinations of psychomotor delay, ataxia, eye movement abnormalities, spasticity, dystonia, and neuropathic symptoms. Cerebellar signs, nystagmus, and pyramidal tract dysfunction emerged as unifying features in the majority of MAG-mutated individuals identified to date.ConclusionsOur study is the first to describe biallelic null variants in MAG, confirming that loss of myelin-associated glycoprotein causes severe infancy-onset disease with central and peripheral nervous system involvement.     

Neutral lipid storage disease with myopathy: Further phenotypic characterization of a rare PNPLA2 variant

Neutral lipid storage disease with myopathy is a rare disorder of lipid metabolism caused by variants in the Patatin-Like Phospholipase Domain Containing 2 (PNPLA2) gene. Diagnosis is often delayed due to variable presentations, which is of concern due to increased risk of cardiomyopathy. Better phenotype–genotype characterization is necessary to improve speed and accuracy of diagnosis. Here, we describe a 32-year-old woman of Hmong descent with progressive muscle pain and weakness who had a muscle biopsy with characteristic features of a lipid storage myopathy. Genetic testing revealed a homozygous splice site variant in PNPLA2, c.757 + 1G > T. This case, in combination with the one previously reported case of this PNPLA2 variant, also in a family of Hmong descent, suggests this particular variant may be unique to the Hmong population, a Southeast Asian minority group living in the United States, who immigrated to the United States as refugees after the Vietnam War.     

Association of TNF-α-3959T/C Gene Polymorphisms in the Chinese Population with Intracranial Aneurysms

Recent studies have demonstrated that cytokines play an important role in the pathogenesis of intracranial aneurysm (IA). Tumor necrosis factor-α (TNF-α) is an important proinflammatory cytokine, which was shown to influence the development of IA, but there is no research data from China. Hence, the purpose of this study was to explore the relationship between TNF-α polymorphisms and IA in China. The association of genetic variants of TNF-α gene expression was investigated in a Chinese population with IA. The TNF-α-3959T>C(rs1799964), 4127C>A(rs1800630), 4133C>T(rs1799724), 4184C>T(rs4248158), and 4752G>A(rs361525) gene polymorphisms in 192 IA cases and 112 controls were analyzed using polymerase chain reaction (PCR). Differences in genotype and allele frequencies between patients and controls were tested. There were no significant differences in 4127C>A (p = 0.072), 4133C>T (p = 0.373), 4184C>T (p = 0.749), and 4752G>A (p = 0.184) genotype frequencies between the IA group and the control group. But this case-control association study revealed that TNF-α-3959T>C (p < 0.001) was significantly associated with increased risk of IA. These results suggested that a novel TNF-α locus was found to be closely correlated with the occurrence of IA in Chinese.     

Humoral immunodeficiency in congenital insensitivity to pain with anhidrosis

Congenital insensitivity to pain with anhidrosis (CIPA) is an autosomal recessive disorder caused by mutations in the neurotrophic tyrosine receptor kinase 1 (NTRK1) gene, which encodes the receptor for nerve growth factor. We report the clinical course of a 7-year-old girl with CIPA and proven NTRK1 mutation. In addition to recurrent dislocation of the left hip joint and avascular necrosis of the left talus, the patient also presented with recurrent infections secondary to hypogammaglobulinemia, a feature not previously known to be associated with CIPA. The patient was treated with regular administration of intravenous immunoglobulins. Conservative treatment of the recurrent left hip dislocation by cast immobilization and bracing was implemented to stabilize the joint. The implication of the immune system of the reported patient broadens the clinical phenotype associated with NTRK1 mutations.     

Nerve growth factor, pain, itch and inflammation: lessons from congenital insensitivity to pain with anhidrosis

NGF is a well-known neurotrophic factor essential for the survival and maintenance of primary afferent neurons and sympathetic neurons. NGF is also an inflammatory mediator associated with pain and itch. Congenital insensitivity to pain with anhidrosis is a genetic disorder due to loss-of-function mutations in the NTRK1 gene encoding TrkA, a receptor tyrosine kinase for NGF. Since patients with congenital insensitivity to pain with anhidrosis lack NGF-dependent unmyelinated (C-) and thinly myelinated (Aδ-) fibers, and their dermal sweat glands are without innervation, they exhibit no pain, itch, signs of neurogenic inflammation or sympathetic skin responses. Based on the pathophysiology of congenital insensitivity to pain with anhidrosis, this article indicates how NGF-dependent neurons are essential for the establishment of neural networks for interoception and homeostasis, and play crucial roles in brain-immune-endocrine interactions in pain, itch and inflammation. In addition, it refers to involvements of the NGF-TrkA system in various disease states, and potential pharmacological effects when this system is targeted.     

A case of QARS1 associated epileptic encephalopathy and review of epilepsy in aminoacyl-tRNA synthetase disorders

IntroductionMutations in QARS1, which encodes human glutaminyl-tRNA synthetase, have been associated with epilepsy, developmental regression, progressive microcephaly and cerebral atrophy. Epilepsy caused by variants in QARS1 is usually drug-resistant and intractable. Childhood onset epilepsy is also reported in various aminoacyl-tRNA synthetase disorders. We describe a case with a milder neurological phenotype than previously reported with QARS1 variants and review the seizure associations with aminoacyl-tRNA synthetase disorders.Case reportThe patient is a 4-year-old girl presenting at 6 weeks of age with orofacial dyskinesia and hand stereotypies. She developed focal seizures at 7 months of age. Serial electroencephalograms showed shifting focality. Her seizures were controlled after introduction of carbamazepine. Progress MRI showed very mild cortical volume loss without myelination abnormalities or cerebellar atrophy. She was found to have novel compound heterozygous variants in QARS1 (NM_005051.2): c.[1132C > T];[1574G > A], p.[(Arg378Cys)];[(Arg525Gln)] originally classified as “variants of uncertain significance” and later upgraded to “likely pathogenic” based on functional testing and updated variant database review. Functional testing showed reduced solubility of the corresponding QARS1 mutants in vitro, but only mild two-fold loss in catalytic efficiency with the c.1132C > T variant and no noted change in tRNA^Gln aminoacylation with the c.1574G > A variant.ConclusionWe describe two QARS1 variants associated with overall conserved tRNA aminoacylation activity but characterized by significantly reduced QARS protein solubility, resulting in a milder clinical phenotype. 86% of previous patients reported with QARS1 had epilepsy and 79% were pharmaco-resistant. We also summarise literature regarding epilepsy in aminoacyl-tRNA synthetase disorders, which is also often early onset, severe and drug-refractory.     

Phenotypes of SMA patients retaining SMN1 with intragenic mutation

BackgroundSpinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by homozygous deletion or intragenic mutation of the SMN1 gene. It is well-known that high copy number of its homologous gene, SMN2, modifies the phenotype of SMN1-deleted patients. However, in the patients with intragenic SMN1 mutation, the relationship between phenotype and SMN2 copy number remains unclear.MethodsWe have analyzed a total of 515 Japanese patients with SMA-like symptoms (delayed developmental milestones, respiratory failures, muscle weakness etc.) from 1996 to 2019. SMN1 and SMN2 copy numbers were determined by quantitative polymerase chain reaction (PCR) method and/or multiplex ligation-dependent probe amplification (MLPA) method. Intragenic SMN1 mutations were identified through DNA and RNA analysis of the fresh blood samples.ResultsA total of 241 patients were diagnosed as having SMA. The majority of SMA patients showed complete loss of SMN1 (n = 228, 95%), but some patients retained SMN1 and carried an intragenic mutation in the retaining SMN1 (n = 13, 5%). Ten different mutations were identified in these 13 patients, consisting of missense, nonsense, frameshift and splicing defect-causing mutations. The ten mutations were c.275G > C (p.Trp92Ser), c.819_820insT (p.Thr274Tyrfs*32), c.830A > G (p.Tyr277Cys), c.5C > T (p.Ala2Val), c.826 T > C (p.Tyr276His), c.79C > T (p.Gln27*), c.188C > A (p.Ser63*), c.422 T > C (p.Leu141Pro), c.835-2A > G (exon 7 skipping) and c.835-3C > A (exon 7 skipping). It should be noted here that some patients with milder phenotype carried only a single SMN2 copy (n = 3), while other patients with severe phenotype carried 3 SMN2 copies (n = 4).ConclusionIntragenic mutations in SMN1 may contribute more significantly to clinical severity than SMN2 copy numbers.     

A new alpha-synuclein missense variant (Thr72Met) in two Turkish families with Parkinson's disease

IntroductionMissense variants and multiplications of the alpha-synuclein gene (SNCA) are established as rare causes of autosomal dominant forms of Parkinson's Disease (PD).MethodsTwo families of Turkish origins with PD were studied; the SNCA coding region was analyzed by Sanger sequencing, and by whole exome sequencing (WES) in the index patient of the first and the second family, respectively. Co-segregation studies and haplotype analysis across the SNCA locus were carried out. Functional studies included in vitro thioflavin-T aggregation assay and in silico structural modelling of the alpha-synuclein (α-syn) protein.ResultsWe identified a novel heterozygous SNCA variant, c.215C > T (p.Thr72Met), segregating with PD in a total of four members in the two families. A shared haplotype across the SNCA locus was found among variant carriers, suggestive of a common ancestor. We next showed that the Thr72Met α-syn displays enhanced aggregation in-vitro, compared to the wild-type species. In silico analysis of a tetrameric α-syn structural model revealed that Threonine 72 lies in the tetrameric interface, and substitution with the much larger methionine residue could potentially destabilize the tetramer.ConclusionWe present clinical, genetic, and functional data supporting a causative role of the SNCA c.215C > T (p.Thr72Met) variant in familial PD. Testing for this variant in patients with PD, especially of Turkish origin, might detect additional carriers. Further functional analyses might offer new insights into the shared biochemical properties of the PD-causing SNCA missense variants, and how they lead to neurodegeneration.     

A novel pathogenic compound heterozygous variant in C12orf57 gene in a child with Temtamy syndrome presenting with overlapping phenotypic features of Kabuki-like syndrome

BackgroundAutism spectrum disorder is a major neurodevelopmental disorder. Temtamy syndrome is a rare syndromic intellectual developmental disorder that presents with global developmental delay, autism, seizures, and agenesis/dysgenesis of the corpus callosum.MethodsWe report a case of a male child who presented with global developmental delay, and autism. Additional clinical features in the child were prominent eyes, long palpebral fissures with eversion of lateral third of the lower eyelid, hypoplastic nipples, and persistent fetal fingertip pads. The clinical features were in favor of Kabuki-like syndrome. MRI brain revealed corpus callosal dysgenesis, mild cerebellar para-vermian, and vermian atrophy.ResultsTrio exome sequencing has revealed a novel pathogenic compound heterozygous variant c.145A >T (p.Lys49Ter) and c.224_242del (p.Val85GlufsTer88) in exon 2 of the C12orf57 gene.ConclusionThis is the first case of Temtamy syndrome reported from India with additional novel phenotypic features not reported previously and broadens the phenotypic spectrum of the disorder. In addition, it expands the spectrum of pathogenic variants in the C12orf57 gene.     

A rare variant in TOR1A exon 5 associated with isolated dystonia in southwestern Chinese

Background: TOR1A has been proposed as an important genetic factor in early‐onset isolated dystonia. Variants located in the 3′ untranslated region of TOR1A are of particular importance because they may influence gene expression, although related studies are limited. The objectives of the present study focused on variants in the TOR1A 3′ untranslated region. Methods: The last exon of TOR1A was sequenced in 229 cases with isolated dystonia and in 210 controls. In addition, 471 controls were tested to determine the frequency of the variants in the 3′ untranslated region. Results: Except for c.904_906delGAG, 3 rare sequence variants (NM_000113.2:c.*454T>A, NM_000113.2:c.860C>A [rs766483672], and NM_000113.2:c.*302T>A [rs563498119]) were found only in the patients. The c.*302T>A variant was located in the conserved region of the human microRNA (hsa‐miR‐494) binding site. A luciferase reporter assay showed that c.*302T>A significantly altered gene expression. Conclusions: Population frequencies, computational analyses, and function experiments in this study implied that c.*302T>A is associated with dystonia. © 2017 International Parkinson and Movement Disorder Society