Phenotypic expansion in KIF1A-related dominant disorders: A description of novel variants and review of published cases.
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ABSTRACT:
SUBMITTER: Montenegro-Garreaud X
PROVIDER: S-EPMC7903881 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Defects in the motor domain of kinesin family member 1A (KIF1A), a neuron-specific ATP-dependent anterograde axonal transporter of synaptic cargo, are well-recognized to cause a spectrum of neurological conditions, commonly known as KIF1A-associated neurological disorders (KAND). Here, we report one mutation-negative female with classic Rett syndrome (RTT) harboring a de novo heterozygous novel variant [NP_001230937.1:p.(Asp248Glu)] in the highly conserved motor domain of KIF1A. In addition, three individuals with severe neurodevelopmental disorder along with clinical features overlapping with KAND are also reported carrying de novo heterozygous novel [NP_001230937.1:p.(Cys92Arg) and p.(Pro305Leu)] or previously reported [NP_001230937.1:p.(Thr99Met)] variants in KIF1A. In silico tools predicted these variants to be likely pathogenic, and 3D molecular modeling predicted defective ATP hydrolysis and/or microtubule binding. Using the neurite tip accumulation assay, we demonstrated that all novel KIF1A variants significantly reduced the ability of the motor domain of KIF1A to accumulate along the neurite lengths of differentiated SH-SY5Y cells. In vitro microtubule gliding assays showed significantly reduced velocities for the variant p.(Asp248Glu) and reduced microtubule binding for the p.(Cys92Arg) and p.(Pro305Leu) variants, suggesting a decreased ability of KIF1A to move along microtubules. Thus, this study further expanded the phenotypic characteristics of KAND individuals with pathogenic variants in the KIF1A motor domain to include clinical features commonly seen in RTT individuals.
| S-EPMC7908811 | biostudies-literature
Project description:Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS) is a recently described autosomal dominant disorder caused by mutations in the NR2F1 gene. There are presently 28 cases of BBSOAS described in the literature. Its common features include developmental delay, intellectual disability, hypotonia, optic nerve atrophy, attention deficit disorder, autism spectrum disorder, seizures, hearing defects, spasticity, and thinning of the corpus callosum. Here we report two unrelated probands with novel, de novo, missense variants in NR2F1 The first is a 14-yr-old male patient with hypotonia, intellectual disability, optic nerve hypoplasia, delayed bone age, short stature, and altered neurotransmitter levels on cerebrospinal fluid testing. The second is a 5-yr-old female with severe developmental delay, motor and speech delay, and repetitive motion behavior. Whole-exome sequencing identified a novel missense NR2F1 variant in each case, Cys86Phe in the DNA-binding domain in Case 1, and a Leu372Pro in the ligand-binding domain in Case 2. The presence of clinical findings compatible with BBSOAS along with structural analysis at atomic resolution using homology-based molecular modeling and molecular dynamic simulations, support the pathogenicity of these variants for BBSOAS. Short stature, abnormal CNS neurotransmitters, and macrocephaly have not been previously reported for this syndrome and may represent a phenotypic expansion of BBSOAS. A review of published cases along with new evidence from this report support genotype-phenotype correlations for this disorder.
| S-EPMC5701304 | biostudies-literature
Project description:Mitochondrial complex V (CV) generates cellular energy as adenosine triphosphate (ATP). Mitochondrial disease caused by the m.8993T>G pathogenic variant in the CV subunit gene MT-ATP6 was among the first described human mitochondrial DNA diseases. Due to a lack of clinically available functional assays, validating the definitive pathogenicity of additional MT-ATP6 variants remains challenging. We reviewed all reportedMT-ATP6 disease cases ( n = 218) to date, to assess for MT-ATP6 variants, heteroplasmy levels, and inheritance correlation with clinical presentation and biochemical findings. We further describe the clinical and biochemical features of a new cohort of 14 kindreds with MT-ATP6 variants of uncertain significance. Despite extensive overlap in the heteroplasmy levels of MT-ATP6 variant carriers with and without a wide range of clinical symptoms, previously reported symptomatic subjects had significantly higher heteroplasmy load (p = 2.2 x 10-16 ). Pathogenic MT-ATP6 variants resulted in diverse biochemical features. The most common findings were reduced ATP synthesis rate, preserved ATP hydrolysis capacity, and abnormally increased mitochondrial membrane potential. However, no single biochemical feature was universally observed. Extensive heterogeneity exists among both clinical and biochemical features of distinct MT-ATP6 variants. Improved mechanistic understanding and development of consistent biochemical diagnostic analyses are needed to permit accurate pathogenicity assessment of variants of uncertain significance in MT-ATP6.
| S-EPMC6506718 | biostudies-literature
Project description:Variants in the KIF1A gene can cause autosomal recessive spastic paraplegia 30, autosomal recessive hereditary sensory neuropathy, or autosomal (de novo) dominant mental retardation type 9. More recently, variants in KIF1A have also been described in a few cases with autosomal dominant spastic paraplegia. Here, we describe 20 KIF1A variants in 24 patients from a clinical exome sequencing cohort of 347 individuals with a mostly 'pure' spastic paraplegia. In these patients, spastic paraplegia was slowly progressive and mostly pure, but with a highly variable disease onset (0-57 years). Segregation analyses showed a de novo occurrence in seven cases, and a dominant inheritance pattern in 11 families. The motor domain of KIF1A is a hotspot for disease causing variants in autosomal dominant spastic paraplegia, similar to mental retardation type 9 and recessive spastic paraplegia type 30. However, unlike these allelic disorders, dominant spastic paraplegia was also caused by loss-of-function variants outside this domain in six families. Finally, three missense variants were outside the motor domain and need further characterization. In conclusion, KIF1A variants are a frequent cause of autosomal dominant spastic paraplegia in our cohort (6-7%). The identification of KIF1A loss-of-function variants suggests haploinsufficiency as a possible mechanism in autosomal dominant spastic paraplegia.
| S-EPMC6906463 | biostudies-literature
Project description:A recurrent de novo missense variant in KCNC1, encoding a voltage-gated potassium channel expressed in inhibitory neurons, causes progressive myoclonus epilepsy and ataxia, and a nonsense variant is associated with intellectual disability. We identified three new de novo missense variants in KCNC1 in five unrelated individuals causing different phenotypes featuring either isolated nonprogressive myoclonus (p.Cys208Tyr), intellectual disability (p.Thr399Met), or epilepsy with myoclonic, absence and generalized tonic-clonic seizures, ataxia, and developmental delay (p.Ala421Val, three patients). Functional analyses demonstrated no measurable currents for all identified variants and dominant-negative effects for p.Thr399Met and p.Ala421Val predicting neuronal disinhibition as the underlying disease mechanism.
| S-EPMC6649617 | biostudies-literature
Project description:PEHO syndrome (OMIM no. 260565) is characterized by myoclonic jerking and infantile spasms, profound psychomotor retardation with the absence of motor milestones and speech, absence or early loss of visual fixation with atrophy of optic discs by 2 years of age and progressive brain atrophy on neuroimaging. We describe the results of a genomic study of a girl with PEHO syndrome and review the literature on cases with a disease-causing variant in the same gene. Exome sequencing of the index and unaffected parents followed by Sanger confirmation identified nine candidate genes harboring nonsynonymous rare variants identified by trio whole-exome sequencing. The de novo variant, a missense variant (c.296C>T, p.(T99M)), affecting the motor domain of KIF1A was considered the pathogenic mutation. The literature review revealed 24 cases with disease-causing variants in the motor domain of KIF1A, of which three met all the criteria for PEHO syndrome and an additional patient with incomplete clinical data met four of the five criteria. If the criteria were modified to include cases with any convulsive disorder and less profound intellectual disability, a total of six patients met all five of the criteria, three patients met four of the criteria and six met three of the criteria. Our results indicate that the molecular basis for PEHO syndrome, in at least a subset of patients, is a dominant KIF1A variant affecting the motor domain of the protein. Variable expressivity is seen with recurrent variants causing the full phenotype of PEHO syndrome in some patients and in other patients, a partial or milder PEHO phenotype.
| S-EPMC4867456 | biostudies-literature
Project description:IntroductionTakotsubo cardiomyopathy (TCM) features transient left ventricular apical dysfunction or ballooning. The underlying mechanism remains elusive; however, evidence suggests the role of different physical and psychological stressors. We systematically reviewed patients presenting with TCM and autoimmunity to explore the link between the two conditions.MethodsWe applied the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) to report this review. Using keywords related to autoimmune/immune-mediated diseases and TCM, we searched PubMed, Scopus, and WOS in March 2022. The final results were added to a data extraction sheet. Data were analyzed by SPSS version 26.0.ResultsOur search yielded 121 studies, including 155 patients. Females were considerably predominant. Most patients had a history of autoimmune disease, and almost a third had a history of cardiovascular disease. Dyspnea and chest pain were the most common chief complaints. More than 70% of patients had experienced physical stress. Myasthenia gravis, systemic lupus erythematosus, and multiple sclerosis were the most frequently reported autoimmune diseases.ConclusionThere were similarities in age and sex compared to classic TCM. TCM should be considered as a differential diagnosis for ACS, especially in patients with a positive background of autoimmunity. A precise reporting system is required for further studies.
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Project description:Heterozygous mutations in KMT2B are associated with an early-onset, progressive and often complex dystonia (DYT28). Key characteristics of typical disease include focal motor features at disease presentation, evolving through a caudocranial pattern into generalized dystonia, with prominent oromandibular, laryngeal and cervical involvement. Although KMT2B-related disease is emerging as one of the most common causes of early-onset genetic dystonia, much remains to be understood about the full spectrum of the disease. We describe a cohort of 53 patients with KMT2B mutations, with detailed delineation of their clinical phenotype and molecular genetic features. We report new disease presentations, including atypical patterns of dystonia evolution and a subgroup of patients with a non-dystonic neurodevelopmental phenotype. In addition to the previously reported systemic features, our study has identified co-morbidities, including the risk of status dystonicus, intrauterine growth retardation, and endocrinopathies. Analysis of this study cohort (n = 53) in tandem with published cases (n = 80) revealed that patients with chromosomal deletions and protein truncating variants had a significantly higher burden of systemic disease (with earlier onset of dystonia) than those with missense variants. Eighteen individuals had detailed longitudinal data available after insertion of deep brain stimulation for medically refractory dystonia. Median age at deep brain stimulation was 11.5 years (range: 4.5-37.0 years). Follow-up after deep brain stimulation ranged from 0.25 to 22 years. Significant improvement of motor function and disability (as assessed by the Burke Fahn Marsden's Dystonia Rating Scales, BFMDRS-M and BFMDRS-D) was evident at 6 months, 1 year and last follow-up (motor, P = 0.001, P = 0.004, and P = 0.012; disability, P = 0.009, P = 0.002 and P = 0.012). At 1 year post-deep brain stimulation, >50% of subjects showed BFMDRS-M and BFMDRS-D improvements of >30%. In the long-term deep brain stimulation cohort (deep brain stimulation inserted for >5 years, n = 8), improvement of >30% was maintained in 5/8 and 3/8 subjects for the BFMDRS-M and BFMDRS-D, respectively. The greatest BFMDRS-M improvements were observed for trunk (53.2%) and cervical (50.5%) dystonia, with less clinical impact on laryngeal dystonia. Improvements in gait dystonia decreased from 20.9% at 1 year to 16.2% at last assessment; no patient maintained a fully independent gait. Reduction of BFMDRS-D was maintained for swallowing (52.9%). Five patients developed mild parkinsonism following deep brain stimulation. KMT2B-related disease comprises an expanding continuum from infancy to adulthood, with early evidence of genotype-phenotype correlations. Except for laryngeal dysphonia, deep brain stimulation provides a significant improvement in quality of life and function with sustained clinical benefit depending on symptoms distribution.
| S-EPMC7719027 | biostudies-literature
Project description:Biallelic TENM3 variants were recently reported to cause non-syndromic microphthalmia with coloboma-9 (MCOPCB9) and microphthalmia and/or coloboma with developmental delay (MCOPS15). To date, only eight syndromic and non-syndromic microphthalmia cases with recessive TENM3 variants have been reported. Herein, we report two unrelated new cases with biallelic variants in TENM3, widening the molecular and clinical spectrum. Regarding patient 1, WES revealed compound heterozygous variants in the TENM3 gene: c.3847_3855del; p.Leu1283_Ser1285del and c.3698_3699insA; p.Thr1233Thrfs*20 in the index patient, who was presenting with bilateral microphthalmia, congenital cataract, microcephaly, and global developmental delay. Regarding patient 2, compound missense heterozygous variants in the TENM3 gene were identified: c.941C > T; p.Ala314Val and c.6464T > C; p.Leu2155Pro in the 3-year-old boy, who presented with congenital esotropia, speech delay, and motor developmental delay. The clinical features of these two cases revealed high concordance with the previously reported cases, including microphthalmia and developmental delay. The presence of microcephaly in our patient potentially expands the neurologic phenotype associated with loss of function variants in TENM3, as microcephaly has not previously been described. Furthermore, we present evidence that missense variants in TENM3 are associated with similar, but milder, ocular features.
| S-EPMC9998998 | biostudies-literature
Project description:Early infantile epileptic encephalopathy-44 (EIEE44, MIM: 617132) is a previously described condition resulting from biallelic variants in UBA5, a gene involved in a ubiquitin-like post-translational modification system called UFMylation. Here we report five children from four families with biallelic pathogenic variants in UBA5 All five children presented with global developmental delay, epilepsy, axial hypotonia, appendicular hypertonia, and a movement disorder, including dystonia in four. Affected individuals in all four families have compound heterozygous pathogenic variants in UBA5 All have the recurrent mild c.1111G > A (p.Ala371Thr) variant in trans with a second UBA5 variant. One patient has the previously described c.562C > T (p. Arg188*) variant, two other unrelated patients have a novel missense variant, c.907T > C (p.Cys303Arg), and the two siblings have a novel missense variant, c.761T > C (p.Leu254Pro). Functional analyses demonstrate that both the p.Cys303Arg variant and the p.Leu254Pro variants result in a significant decrease in protein function. We also review the phenotypes and genotypes of all 15 previously reported families with biallelic UBA5 variants, of which two families have presented with distinct phenotypes, and we describe evidence for some limited genotype-phenotype correlation. The overlap of motor and developmental phenotypes noted in our cohort and literature review adds to the increasing understanding of genetic syndromes with movement disorders-epilepsy.
| S-EPMC8208045 | biostudies-literature