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- Ain, Noor Ul, et al.
(författare)
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Novel form of rhizomelic skeletal dysplasia associated with a homozygous variant in GNPNAT1
- 2021
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Ingår i: Journal of Medical Genetics. - : BMJ Publishing Group Ltd. - 0022-2593 .- 1468-6244. ; 58:5, s. 351-356
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Studies exploring molecular mechanisms underlying congenital skeletal disorders have revealed novel regulators of skeletal homeostasis and shown protein glycosylation to play an important role.OBJECTIVE: To identify the genetic cause of rhizomelic skeletal dysplasia in a consanguineous Pakistani family.METHODS: Clinical investigations were carried out for four affected individuals in the recruited family. Whole genome sequencing (WGS) was completed using DNA from two affected and two unaffected individuals from the family. Sequencing data were processed, filtered and analysed. In silico analyses were performed to predict the effects of the candidate variant on the protein structure and function. Small interfering RNAs (siRNAs) were used to study the effect of Gnpnat1 gene knockdown in primary rat chondrocytes.RESULTS: The patients presented with short stature due to extreme shortening of the proximal segments of the limbs. Radiographs of one individual showed hip dysplasia and severe platyspondyly. WGS data analyses identified a homozygous missense variant c.226G>A; p.(Glu76Lys) in GNPNAT1, segregating with the disease. Glucosamine 6-phosphate N-acetyltransferase, encoded by the highly conserved gene GNPNAT1, is one of the enzymes required for synthesis of uridine diphosphate N-acetylglucosamine, which participates in protein glycosylation. Knockdown of Gnpnat1 by siRNAs decreased cellular proliferation and expression of chondrocyte differentiation markers collagen type 2 and alkaline phosphatase, indicating that Gnpnat1 is important for growth plate chondrocyte proliferation and differentiation.CONCLUSIONS: This study describes a novel severe skeletal dysplasia associated with a biallelic, variant in GNPNAT1. Our data suggest that GNPNAT1 is important for growth plate chondrogenesis.
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- Björkman, Kristoffer, et al.
(författare)
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Phenotypic spectrum and clinical course of single large-scale mitochondrial DNA deletion disease in the paediatric population: a multicentre study.
- 2021
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Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 60:1, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- Background Large-scale mitochondrial DNA deletions (LMD) are a common genetic cause of mitochondrial disease and give rise to a wide range of clinical features. Lack of longitudinal data means the natural history remains unclear. This study was undertaken to describe the clinical spectrum in a large cohort of patients with paediatric disease onset. Methods A retrospective multicentre study was performed in patients with clinical onset <16 years of age, diagnosed and followed in seven European mitochondrial disease centres. Results A total of 80 patients were included. The average age at disease onset and at last examination was 10 and 31 years, respectively. The median time from disease onset to death was 11.5 years. Pearson syndrome was present in 21%, Kearns-Sayre syndrome spectrum disorder in 50% and progressive external ophthalmoplegia in 29% of patients. Haematological abnormalities were the hallmark of the disease in preschool children, while the most common presentations in older patients were ptosis and external ophthalmoplegia. Skeletal muscle involvement was found in 65% and exercise intolerance in 25% of the patients. Central nervous system involvement was frequent, with variable presence of ataxia (40%), cognitive involvement (36%) and stroke-like episodes (9%). Other common features were pigmentary retinopathy (46%), short stature (42%), hearing impairment (39%), cardiac disease (39%), diabetes mellitus (25%) and renal disease (19%). Conclusion Our study provides new insights into the phenotypic spectrum of childhood-onset, LMD-associated syndromes. We found a wider spectrum of more prevalent multisystem involvement compared with previous studies, most likely related to a longer time of follow-up.
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