Correction to: Recessive VARS2 mutation underlies a novel syndrome with epilepsy, mental retardation, short stature, growth hormone deficiency, and hypogonadism

Correction After publication of the article [1], it has been brought to our attention that there is a nomenclature issue with this article. At the time of acceptance, the VARS2 mutation was considered equivalent to the VARS2 mutation. However, this has changed so that VARS now only refers to shorter mitochondrial sequence of valyl-tRNA synthesase containing 1093 amino acids. “Therefore, in the context of this article, every usage of “VARS2” should be replaced with “VARS” when referring to the causative variant”

Identification of a novel genetic locus underlying tremor and dystonia

Abstract Background Five affected individuals with syndromic tremulous dystonia, spasticity, and white matter disease from a consanguineous extended family covering a period of over 24 years are presented. A positional cloning approach utilizing genome-wide linkage, homozygozity mapping and whole exome sequencing was used for genetic characterization. The impact of a calmodulin-binding transcription activator 2, (CAMTA2) isoform 2, hypomorphic mutation on mRNA and protein abundance was studied using fluorescent reporter expression cassettes. Human brain sub-region cDNA libraries were used to study the expression pattern of CAMTA2 transcript variants. Results Linkage analysis and homozygozity mapping localized the disease allele to a 2.1 Mb interval on chromosome 17 with a LOD score of 4.58. Whole exome sequencing identified a G>A change in the transcript variant 2 5′UTR of CAMTA2 that was only 6 bases upstream of the translation start site (c.-6G > A) (NM_001171166.1) and segregated with disease in an autosomal recessive manner. Transfection of wild type and mutant 5′UTR-linked fluorescent reporters showed no impact upon mRNA levels but a significant reduction in the protein fluorescent activity implying translation inhibition. Conclusions Mutation of CAMTA2 resulting in post-transcriptional inhibition of its own gene activity likely underlies a novel syndromic tremulous dystonia

Additional file 2: of Identification of a novel genetic locus underlying tremor and dystonia

Variants in candidate interval. (PDF 217 kb

The clinical utility of rapid exome sequencing in a consanguineous population

Abstract Background The clinical utility of exome sequencing is now well documented. Rapid exome sequencing (RES) is more resource-intensive than regular exome sequencing and is typically employed in specialized clinical settings wherein urgent molecular diagnosis is thought to influence acute management. Studies on the clinical utility of RES have been largely limited to outbred populations. Methods Here, we describe our experience with rapid exome sequencing (RES) in a highly consanguineous population. Clinical settings included intensive care units, prenatal cases approaching the legal cutoff for termination, and urgent transplant decisions. Results A positive molecular finding (a pathogenic or likely pathogenic variant that explains the phenotype) was observed in 80 of 189 cases (42%), while 15 (8%) and 94 (50%) received ambiguous (variant of uncertain significance (VUS)) and negative results, respectively. The consanguineous nature of the study population gave us an opportunity to observe highly unusual and severe phenotypic expressions of previously reported genes. Clinical utility was observed in nearly all (79/80) cases with positive molecular findings and included management decisions, prognostication, and reproductive counseling. Reproductive counseling is a particularly important utility in this population where the overwhelming majority (86%) of identified variants are autosomal recessive, which are more actionable in this regard than the de novo variants typically reported by RES elsewhere. Indeed, our cost-effectiveness analysis shows compelling cost savings in the study population. Conclusions This work expands the diversity of environments in which RES has a demonstrable clinical utility

Additional file 4: of Identification of a novel genetic locus underlying tremor and dystonia

CAMTA2 expression in brain. (PDF 1628 kb

Additional file 1: of A first-line diagnostic assay for limb-girdle muscular dystrophy and other myopathies

Clinical characteristics and biopsy results of index cases for families studied. (DOCX 223 kb

Additional file 2: of A first-line diagnostic assay for limb-girdle muscular dystrophy and other myopathies

Genes included in the neurological panel. (DOC 97 kb

Bi-allelic variants in HOPS complex subunit VPS41 cause cerebellar ataxia and abnormal membrane trafficking

Membrane trafficking is a complex, essential process in eukaryotic cells responsible for protein transport and processing. Deficiencies in vacuolar protein sorting (VPS) proteins, key regulators of trafficking, cause abnormal intracellular segregation of macromolecules and organelles and are linked to human disease. VPS proteins function as part of complexes such as the homotypic fusion and vacuole protein sorting (HOPS) tethering complex, composed of VPS11, VPS16, VPS18, VPS33A, VPS39 and VPS41. The HOPS-specific subunit VPS41 has been reported to promote viability of dopaminergic neurons in Parkinson's disease but to date has not been linked to human disease. Here, we describe five unrelated families with nine affected individuals, all carrying homozygous variants in VPS41 that we show impact protein function. All affected individuals presented with a progressive neurodevelopmental disorder consisting of cognitive impairment, cerebellar atrophy/hypoplasia, motor dysfunction with ataxia and dystonia, and nystagmus. Zebrafish disease modelling supports the involvement of VPS41 dysfunction in the disorder, indicating lysosomal dysregulation throughout the brain and providing support for cerebellar and microglial abnormalities when vps41 was mutated. This provides the first example of human disease linked to the HOPS-specific subunit VPS41 and suggests the importance of HOPS complex activity for cerebellar function