Three novel mutations of the spastin gene in Chinese patients with hereditary spastic paraplegia

Ochratoxin A as alarming health in livestock and human: A review on molecular interactions, mechanism of toxicity, detection, detoxification, and dietary prophylaxis

Ochratoxin A (OTA) is a toxic metabolite produced by Aspergillus and Penicillium fungi commonly found in raw plant sources and other feeds. This review comprises an extensive evaluation of the origin and proprieties of OTA, toxicokinetics, biotransformation, and toxicodynamics of ochratoxins. In in vitro and in vivo studies, the compatibility of OTA with oxidative stress is observed through the production of free radicals, resulting in genotoxicity and carcinogenicity. The OTA leads to nephrotoxicity as the chief target organ is the kidney. Other OTA excretion and absorption rates are observed, and the routes of elimination include faeces, urine, and breast milk. The alternations in the Phe moiety of OTA are the precursor for the amino acid alternation, bringing about Phe-hydroxylase and Phe-tRNA synthase, resulting in the complete dysfunction of cellular metabolism. Biodetoxification using specific microorganisms decreased the DNA damage, lipid peroxidation, and cytotoxicity. This review addressed the ability of antioxidants and the dietary components as prophylactic measures to encounter toxicity and demonstrated their capability to counteract the chronic exposure through supplementation as feed additives.

Genotype-phenotype associations in hereditary spastic paraplegia: a systematic review and meta-analysis on 13,570 patients

AIMS

The hereditary spastic paraplegias (HSPs) are a heterogeneous group of inherited neurodegenerative disorders. Although, several genotype-phenotype studies have carried out on HSPs, the association between genotypes and clinical phenotypes remain incomplete since most studies are small in size or restricted to a few genes. Accordingly, this study provides the systematic meta-analysis of genotype-phenotype associations in HSP.

METHODS AND RESULTS

We retrieved literature on genotype-phenotype associations in patients with HSP and mutated SPAST, REEP1, ATL1, SPG11, SPG15, SPG7, SPG35, SPG54, SPG5. In total, 147 studies with 13,570 HSP patients were included in our meta-analysis. The frequency of mutations in SPAST (25%) was higher than REEP1 (3%), as well as ATL1 (5%) in AD-HSP patients. As for AR-HSP patients, the rates of mutations in SPG11 (18%), SPG15 (7%) and SPG7 (13%) were higher than SPG5 (5%), as well as SPG35 (8%) and SPG54 (7%). The mean age of AD-HSP onset for ATL1 mutation-positive patients was earlier than patients with SPAST, REEP1 mutations. Also, the tendency toward younger age at AR-HSP onset for SPG35 was higher than other mutated genes. It is noteworthy that the mean age at HSP onset ranged from infancy to adulthood. As for the gender distribution, the male proportion in SPG7-HSP (90%) and REEP1-HSP (78%) was markedly high. The frequency of symptoms was varied among patients with different mutated genes. The rates of LL weakness, superficial sensory abnormalities, neuropathy, and deep sensory impairment were noticeably high in REEP1 mutations carriers. Also, in AR-HSP patients with SPG11 mutations, the presentation of symptoms including pes cavus, Neuropathy, and UL spasticity was higher.

CONCLUSION

Our comprehensive genotype-phenotype assessment of available data displays that the mean age at disease onset and particular sub-phenotypes are associated with specific mutated genes which might be beneficial for a diagnostic procedure and differentiation of the specific mutated genes phenotype among diverse forms of HSP.

Massive sequencing of 70 genes reveals a myriad of missing genes or mechanisms to be uncovered in hereditary spastic paraplegias

Hereditary spastic paraplegias (HSP) are neurodegenerative disorders characterized by lower limb spasticity and weakness that can be complicated by other neurological or non-neurological signs. Despite a high genetic heterogeneity (>60 causative genes), 40–70% of the families remain without a molecular diagnosis. Analysis of one of the pioneer cohorts of 193 HSP families generated in the early 1990s in Portugal highlighted that SPAST and SPG11 are the most frequent diagnoses. We have now explored 98 unsolved families from this series using custom next generation sequencing panels analyzing up to 70 candidate HSP genes. We identified the likely disease-causing variant in 20 of the 98 families with KIF5A being the most frequently mutated gene. We also found 52 variants of unknown significance (VUS) in 38% of the cases. These new diagnoses resulted in 42% of solved cases in the full Portuguese cohort (81/193). Segregation of the variants was not always compatible with the presumed inheritance, indicating that the analysis of all HSP genes regardless of the inheritance mode can help to explain some cases. Our results show that there is still a large set of unknown genes responsible for HSP and most likely novel mechanisms or inheritance modes leading to the disease to be uncovered, but this will require international collaborative efforts, particularly for the analysis of VUS.

A de novo mosaic mutation in SPAST with two novel alternative alleles and chromosomal copy number variant in a boy with spastic paraplegia and autism spectrum disorder

Here we report a 12 year old male with an extreme presentation of spastic paraplegia along with autism and dysmorphisms. Whole exome sequencing identified a predicted pathogenic pair of missense variants in SPAST at the same chromosomal location, each with a different alternative allele, while a chromosome microarray identified a 1.73 Mb paternally inherited copy gain of 1q21.1q21.2 resulting in a blended phenotype of both Spastic paraplegia 4 and 1q21.1 microduplication syndrome. We believe that the extreme phenotype observed is likely caused by the presence of cells which contain only mutant SPAST, but that the viability of the patient is possible due mosaicism of mutant alleles observed in different proportions across tissues.

Exon 8-17 deletions of SPAST in a Chinese family with hereditary spastic paraplegia: a case report and literature review

Hereditary spastic paraplegia (HSP) is a group of clinically and genetically heterogeneous neurodegenerative disorders. SPG4 is the most common autosomal dominant form of HSP subtypes and is caused by mutations of the SPAST gene. Here we reported a Chinese family with HSP caused by deletion of exons 8-17 of the SPAST gene and reviewed the clinical phenotypes of patients with exon deletion that were reported in literatures. The patients with deletions of exons in the SPAST gene showed pure HSP, and the age at onset showed interfamily and intrafamily variations. This study suggests that exon deletion should be examined routinely in patients who are clinically diagnosed with HSP.

Mutation and clinical characteristics of autosomal-dominant hereditary spastic paraplegias in China

BACKGROUND

Hereditary spastic paraplegias constitute a heterogeneous group of inherited neurodegenerative disorders. To date, there has been no systematic mutation and clinical analysis for a large group of autosomal-dominant hereditary spastic paraplegias in China.

OBJECTIVE

The purpose of this study was to investigate the mutation frequencies and the clinical phenotypes of Chinese spastic paraplegia patients.

METHODS

Direct sequencing and a multiplex ligation-dependent probe amplification assay were applied to detect the mutations of SPAST and ATL1 in 54 autosomal-dominant hereditary spastic paraplegia probands and 66 isolated cases. Next, mutations in NIPA1, KIF5A, REEP1 and SLC33A1 were detected in the negative patients. Subsets of spastic paraplegia patients were genotyped for the modifying variants. Further, detailed clinical data regarding the genetically diagnosed families were analysed.

RESULTS

Altogether, 27 families were diagnosed as SPG4, 3 as SPG3A and 1 as SPG6. No mutations in KIF5A, REEP1 or SLC33A1 were found; 9 SPAST mutations were novel. There was no p.S44L or p.P45Q variant in SPAST and no p.G563A variant in HSPD1 in either the 120 spastic paraplegia patients or the 500 controls. There was a remarkable clinical difference between the SPG4 and non-SPG4 patients and even between genders among the SPG4 patients. Non-penetrance and remarkable gender difference were observed in some SPG4 and SPG3A families.

CONCLUSIONS

Our data confirm that hereditary spastic paraplegias in China represent a heterogeneous group of genetic neurodegenerative disorders in autosomal-dominant and apparently sporadic forms. Novel genotype-phenotype correlations were established. © 2014 S. Karger AG, Basel.

Genetic analysis of SPG4 and SPG3A genes in a cohort of Chinese patients with hereditary spastic paraplegia

Hereditary spastic paraplegia (HSP or SPG) is a group of genetically and clinically heterogeneous neurodegenerative disorders. At least 52 different gene loci have been identified so far, involving autosomal dominant (AD), autosomal recessive (AR), X-linked (XL), and maternal inheritance. Mutations in the SPAST (SPG4) and ATL1 (SPG3A) genes are responsible for about 50% of pure AD-HSP patients. In this study, SPAST and ATL1 mutations were screened in 36 unrelated HSP patients (17 probands with AD family history and 19 sporadic HSP patients) by direct sequencing and multiplex ligation dependent probe amplification (MLPA). We identified 3 micro-mutations and 2 exon deletions in SPAST gene and 2 micro-mutations in ATL1 gene. Four of five micro-mutations were novel and del. ex. 13-15 in SPAST was not reported previously. In this cohort of Chinese patients with spastic paraplegia, SPAST and ATL1 mutations were found in 5 of 17 HSP probands with AD family history and in 2 of 19 sporadic HSP patients. Four novel micro-mutations and one novel exon deletion were identified, which broadened the mutational spectrum of the genes.

Mutation analysis of SPAST, ATL1, and REEP1 in Korean Patients with Hereditary Spastic Paraplegia

Background and Purpose

Hereditary spastic paraplegia (HSP) is a genetically heterogeneous group of neurodegenerative disorders that are characterized by progressive spasticity and weakness of the lower limbs. Mutations in the spastin gene (SPAST) are the most common causes of HSP, accounting for 40-67% of autosomal dominant HSP (AD-HSP) and 12-18% of sporadic cases. Mutations in the atlastin-1 gene (ATL1) and receptor expression-enhancing protein 1 gene (REEP1) are the second and third most common causes of AD-HSP, respectively.

Methods

Direct sequence analysis was used to screen mutations in SPAST, ATL1, and REEP1 in 27 unrelated Korean patients with pure and complicated HSP. Multiplex ligation-dependent probe amplification was also performed to detect copy-number variations of the three genes.

Results

Ten different SPAST mutations were identified in 11 probands, of which the following 6 were novel: c.760A>T, c.131C>A, c.1351_1353delAGA, c.376_377dupTA, c.1114A>G, and c.1372A>C. Most patients with SPAST mutations had AD-HSP (10/11, 91%), and the frequency of SPAST mutations accounted for 66.7% (10/15) of the AD-HSP patients. No significant correlation was found between the presence of the SPAST mutation and any of the various clinical parameters of pure HSP. No ATL1 and REEP1 mutations were detected.

Conclusions

We conclude that SPAST mutations are responsible for most Korean cases of genetically confirmed AD-HSP. Our observation of the absence of ATL1 and REEP1 mutations needs to be confirmed in larger series.

Clinical and genetic analysis of four Taiwanese families with autosomal dominant hereditary spastic paraplegia

BACKGROUND/PURPOSE

Hereditary spastic paraplegias (HSPs) are clinically and genetically heterogeneous neurodegenerative disorders. Defects in the SPG4 and SPG3A genes are the two leading causes of HSPs with autosomal dominant inheritance (AD-HSPs). The purpose of this study was to investigate the clinical features and associated genetic mutations in Taiwanese families with AD-HSP.

METHODS

Four kindreds with AD-HSP were recruited, and clinical data were collected from the affected individuals. Genetic studies were conducted in the following order: sequence analysis of the SPG4 gene (SPAST) exons, multiplex ligation-dependent probe amplification to detect genetic rearrangements in SPAST, and sequence analysis of the SPG3A gene exons.

RESULTS

Four different SPAST mutations were detected, including a novel small deletion, a missense mutation, and two gross deletions involving exon 17. Although all symptomatic cases manifested as uncomplicated phenotypes, considerable intrakindred and interkindred variations in terms of age at onset, rate of progression, and severity of disease were observed.

CONCLUSION

Mutation patterns and phenotypic expressivity are heterogeneous in Taiwanese patients with SPG4-related HSP. Genetic rearrangements could be a significant cause of SPG4-related HSP in the Taiwanese population. Assessment of the large deletions that could present in SPAST is warranted when direct sequencing is uninformative.

Detection of novel mutations and review of published data suggests that hereditary spastic paraplegia caused by spastin (SPAST) mutations is found more often in males

BACKGROUND

Hereditary spastic paraplegia (HSP) is characterised in its pure form by slowly progressive spastic paraparesis. Around 40% of autosomal dominant (AD) cases are caused by mutations in SPAST, encoding spastin.

PATIENTS AND METHODS

The clinical and investigation details of all patients with a SPAST mutation identified through our centre were reviewed. All published reports of SPAST mutations where the sex of patients was given were subsequently analysed in order to determine whether there is evidence of one sex being preferentially affected.

RESULTS

In total 22 probable pathogenic changes were detected, including 11 novel ones. One patient carried two adjacent missense mutations. The pathogenicity of a further novel missense mutation is uncertain. Most patients had a pure phenotype, although mild peripheral neuropathy was sometimes present. The total number of patients with SPAST mutations was 27, as three of the previously known mutations were present in more than one person. The excess of males over females in our population (17:10) prompted us to review all published studies where the sex of the patients was given (n=31). A significant excess of males was identified (ratio 1.29, p=0.0007).

CONCLUSIONS

Our results are consistent with data suggesting that SPAST mutations mostly cause a pure HSP phenotype. The excess of males in our sample and in published reports suggests that penetrance or severity may be sex-dependent, and merits further investigation as it may have important implications for counselling.

Mutational spectrum of the SPG4 (SPAST) and SPG3A (ATL1) genes in Spanish patients with hereditary spastic paraplegia

Background

Hereditary Spastic Paraplegias (HSP) are characterized by progressive spasticity and weakness of the lower limbs. At least 45 loci have been identified in families with autosomal dominant (AD), autosomal recessive (AR), or X-linked hereditary patterns. Mutations in the SPAST (SPG4) and ATL1 (SPG3A) genes would account for about 50% of the ADHSP cases.

Methods

We defined the SPAST and ATL1 mutational spectrum in a total of 370 unrelated HSP index cases from Spain (83% with a pure phenotype).

Results

We found 50 SPAST mutations (including two large deletions) in 54 patients and 7 ATL1 mutations in 11 patients. A total of 33 of the SPAST and 3 of the ATL1 were new mutations. A total of 141 (31%) were familial cases, and we found a higher frequency of mutation carriers among these compared to apparently sporadic cases (38% vs. 5%). Five of the SPAST mutations were predicted to affect the pre-mRNA splicing, and in 4 of them we demonstrated this effect at the cDNA level. In addition to large deletions, splicing, frameshifting, and missense mutations, we also found a nucleotide change in the stop codon that would result in a larger ORF.

Conclusions

In a large cohort of Spanish patients with spastic paraplegia, SPAST and ATL1 mutations were found in 15% of the cases. These mutations were more frequent in familial cases (compared to sporadic), and were associated with heterogeneous clinical manifestations.

A novel splicing mutation (c.870+3A>G) in SPG4 in a Korean family with hereditary spastic paraplegia

Hereditary spastic paraplegia (HSP) is a group of genetically heterogenous neurodegenerative disorders characterized by progressive spasticity and weakness of both lower extremities. Herein, we report a novel splicing mutation (c.870+3A>G) in SPG4 in a Korean family with an autosomal dominant-inherited pure HSP. The mutation is located in intron 5, and results in a deletion of the 188bp-sized exon 5. It is likely that the exon 5 deletion leads to spastin dysfunction and cause the typical symptoms and signs of patients.

Exon deletions of SPG4 are a frequent cause of hereditary spastic paraplegia

BACKGROUND

Point mutations in SPG4, the gene encoding spastin, are a frequent cause of autosomal dominant hereditary spastic paraplegia (AD-HSP). However, standard methods for genetic analyses fail to detect exonic microdeletions.

METHODS

121 mutation-negative probands were screened for rearrangements in SPG4 by multiplex ligation-dependent probe amplification.

RESULTS

24 patients with 16 different heterozygotic exon deletions in SPG4 (20%) were identified, ranging from one exon to the whole coding sequence. Comparison with 78 patients with point mutations showed a similar clinical picture but an earlier age at onset.

CONCLUSIONS

Exon deletions in SPG4 are as frequent as point mutations, and SPG4 is responsible for 40% of AD-HSP.

Large deletion involving the 5'-UTR in the spastin gene caused mild phenotype of autosomal dominant hereditary spastic paraplegia

Hereditary spastic paraplegia (HSP) due to mutations in the spastin gene (SPG4) located to 2p22-p21 is the most common form of autosomal dominant (AD) HSP. We performed PCR-based direct sequencing of SPG4, followed by a linkage analysis and subsequent Southern blot analysis in large Japanese kindred where 20 of 33 members were evaluated neurologically, and consequently 6 were affected with HSP. Clinical evaluation showed that the mean age at disease onset of the patients was older and the disability was less severe than those of previously reported typical patients with SPG4 mutations. Direct sequencing of genomic DNA and RT-PCR product did not show a SPG4 mutation despite of a strong linkage to the SPG4 locus at 2p. Southern blot analysis suggested a deletion involving the 5'-UTR of SPG4. Further sequence analysis confirmed a heterozygous 2307-bp deletion spanning from the 5'-UTR to intron 1 of SPG4. The results suggested that transcription of the mutated allele starts from an authentic initiation site, but lacks an authentic translational start site of exon 1 because of a deficient splice donor site and coding region. The abnormal transcripts may result in rapid RNA decay. The novel refractory mutation we identified widens the spectrum of SPG4 mutations. These findings suggest that structural genomic abnormalities of SPG4 are more frequent than expected, and this explains previously reported cases more feasibly in which SPG4 mutations were failed to be identified but the disease was linked to 2p.