Rapamycin and rapalogs for tuberous sclerosis complex

BACKGROUND

Potential benefits of rapamycin or rapalogs for treating people with tuberous sclerosis complex (TSC) have been shown. Currently everolimus (a rapalog) is only approved for TSC-associated renal angiomyolipoma and subependymal giant cell astrocytoma (SEGA), but not other manifestations of TSC. A systematic review needs to establish evidence for rapamycin or rapalogs for various manifestations in TSC. This is an updated review.

OBJECTIVES

To determine the effectiveness of rapamycin or rapalogs in people with TSC for decreasing tumour size and other manifestations and to assess the safety of rapamycin or rapalogs in relation to their adverse effects.

SEARCH METHODS

We identified relevant studies from the Cochrane-Central-Register-of-Controlled-Trials (CENTRAL), Ovid MEDLINE and ongoing trials registries with no language restrictions. We searched conference proceedings and abstract books of conferences. Date of the last searches: 15 July 2022.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-RCTs of rapamycin or rapalogs in people with TSC.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias of each study; a third review author verified the extracted data and risk of bias decisions. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

The current update added seven RCTs, bringing the total number to 10 RCTs (with 1008 participants aged 3 months to 65 years; 484 males). All TSC diagnoses were by consensus criteria as a minimum. In parallel studies, 645 participants received active interventions and 340 placebo. Evidence is low-to-high certainty and study quality is mixed; mostly a low risk of bias across domains, but one study had a high risk of performance bias (lack of blinding) and three studies had a high risk of attrition bias. Manufacturers of the investigational products supported eight studies. Systemic administration Six studies (703 participants) administered everolimus (rapalog) orally. More participants in the intervention arm reduced renal angiomyolipoma size by 50% (risk ratio (RR) 24.69, 95% confidence interval (CI) 3.51 to 173.41; P = 0.001; 2 studies, 162 participants, high-certainty evidence). In the intervention arm, more participants in the intervention arm reduced SEGA tumour size by 50% (RR 27.85, 95% CI 1.74 to 444.82; P = 0.02; 1 study; 117 participants; moderate-certainty evidence) ,and reported more skin responses (RR 5.78, 95% CI 2.30 to 14.52; P = 0.0002; 2 studies; 224 participants; high-certainty evidence). In one 18-week study (366 participants), the intervention led to 25% fewer seizures (RR 1.63, 95% CI 1.27 to 2.09; P = 0.0001) or 50% fewer seizures (RR 2.28, 95% CI 1.44 to 3.60; P = 0.0004); but there was no difference in numbers being seizure-free (RR 5.30, 95% CI 0.69 to 40.57; P = 0.11) (moderate-certainty evidence). One study (42 participants) showed no difference in neurocognitive, neuropsychiatry, behavioural, sensory and motor development (low-certainty evidence). Total adverse events (AEs) did not differ between groups (RR 1.09, 95% CI 0.97 to 1.22; P = 0.16; 5 studies; 680 participants; high-certainty evidence). However, the intervention group experienced more AEs resulting in withdrawal, interruption of treatment, or reduced dose (RR 2.61, 95% CI 1.58 to 4.33; P = 0.0002; 4 studies; 633 participants; high-certainty evidence and also reported more severe AEs (RR 2.35, 95% CI 0.99 to 5.58; P = 0.05; 2 studies; 413 participants; high-certainty evidence). Topical (skin) administration Four studies (305 participants) administered rapamycin topically. More participants in the intervention arm showed a response to skin lesions (RR 2.72, 95% CI 1.76 to 4.18; P < 0.00001; 2 studies; 187 participants; high-certainty evidence) and more participants in the placebo arm reported a deterioration of skin lesions (RR 0.27, 95% CI 0.15 to 0.49; 1 study; 164 participants; high-certainty evidence). More participants in the intervention arm responded to facial angiofibroma at one to three months (RR 28.74, 95% CI 1.78 to 463.19; P = 0.02) and three to six months (RR 39.39, 95% CI 2.48 to 626.00; P = 0.009; low-certainty evidence). Similar results were noted for cephalic plaques at one to three months (RR 10.93, 95% CI 0.64 to 186.08; P = 0.10) and three to six months (RR 7.38, 95% CI 1.01 to 53.83; P = 0.05; low-certainty evidence). More participants on placebo showed a deterioration of skin lesions (RR 0.27, 95% CI 0.15 to 0.49; P < 0.0001; 1 study; 164 participants; moderate-certainty evidence). The intervention arm reported a higher general improvement score (MD -1.01, 95% CI -1.68 to -0.34; P < 0.0001), but no difference specifically in the adult subgroup (MD -0.75, 95% CI -1.58 to 0.08; P = 0.08; 1 study; 36 participants; moderate-certainty evidence). Participants in the intervention arm reported higher satisfaction than with placebo (MD -0.92, 95% CI -1.79 to -0.05; P = 0.04; 1 study; 36 participants; low-certainty evidence), although again with no difference among adults (MD -0.25, 95% CI -1.52 to 1.02; P = 0.70; 1 study; 18 participants; low-certainty evidence). Groups did not differ in change in quality of life at six months (MD 0.30, 95% CI -1.01 to 1.61; P = 0.65; 1 study; 62 participants; low-certainty evidence). Treatment led to a higher risk of any AE compared to placebo (RR 1.72, 95% CI 1.10, 2.67; P = 0.02; 3 studies; 277 participants; moderate-certainty evidence); but no difference between groups in severe AEs (RR 0.78, 95% CI 0.19 to 3.15; P = 0.73; 1 study; 179 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Oral everolimus reduces the size of SEGA and renal angiomyolipoma by 50%, reduces seizure frequency by 25% and 50% and implements beneficial effects on skin lesions with no difference in the total number of AEs compared to placebo; however, more participants in the treatment group required a dose reduction, interruption or withdrawal and marginally more experienced serious AEs compared to placebo. Topical rapamycin increases the response to skin lesions and facial angiofibroma, an improvement score, satisfaction and the risk of any AE, but not severe adverse events. With caution regarding the risk of severe AEs, this review supports oral everolimus for renal angiomyolipoma, SEGA, seizure, and skin lesions, and topical rapamycin for facial angiofibroma.

Gene and schizophrenia in the pregenome and postgenome-wide association studies era: a bibliometric analysis and network visualization

This study aimed to perform a bibliometric analysis on genetic studies in schizophrenia in the pregenome-wide association studies (GWAS) and post-GWAS era. We searched the literature on genes and schizophrenia using the Scopus database. The documents increased with time, especially after the human genome project and International HapMap Project, with the highest citation in 2008. The top occurrence author keywords were discovered to be different in the pre-GWAS and post-GWAS eras, reflecting the progress of genetic studies connected to schizophrenia. Emerging keywords highlighted a trend towards an application of precision medicine, showing an interplay of environmental exposures as well as genetic factors in schizophrenia pathogenesis, progression, and response to therapy. In conclusion, the gene and schizophrenia literature has grown rapidly after the human genome project, and the temporal variation in the author keywords pattern reflects the trend of genetic studies related to schizophrenia in the pre-GWAS and post-GWAS era.

Angiotensin-converting enzyme (ACE) inhibitors for proteinuria and microalbuminuria in people with sickle cell disease

BACKGROUND

Sickle cell disease is a group of disorders characterized by deformation of erythrocytes. Renal damage is a frequent complication in sickle cell disease as a result of long-standing anemia and disturbed circulation through the renal medullary capillaries. Due to the improvement in life expectancy of people with sickle cell disease, there has been a corresponding significant increase in the incidence of renal complications. Microalbuminuria and proteinuria are noted to be a strong predictor of subsequent renal failure. There is extensive experience and evidence with angiotensin-converting enzyme (ACE) inhibitors over many years in a variety of clinical situations for patients who do not have sickle cell disease, but their effect in people with this disease is unknown. It is common practice to administer ACE inhibitors for sickle nephropathy due to their renoprotective properties; however, little is known about their effectiveness and safety in this setting. This is an update of a Cochrane Review first published in 2013 and 2015.

OBJECTIVES

To determine the effectiveness of ACE inhibitor administration in people with sickle cell disease for decreasing intraglomerular pressure, microalbuminuria and proteinuria and to to assess the safety of ACE inhibitors as pertains to their adverse effects.

SEARCH METHODS

The authors searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Hameoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Date of the most recent search: 18 October 2021. We also searched clinical trial registries. Date of the most recent search: 22 August 2021.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials of ACE inhibitors designed to reduce microalbuminuria and proteinuria in people with sickle cell disease compared to either placebo or standard treatment regimen.

DATA COLLECTION AND ANALYSIS

Three authors independently applied the inclusion criteria in order to select studies for inclusion in the review. Two authors assessed the risk of bias of studies and extracted data and the third author verified these assessments.

MAIN RESULTS

Seven studies were identified through the searches. Six studies were excluded. The included study randomized 22 participants (7 males and 15 females) having proteinuria or microalbuminuria with sickle cell disease and treated the participants for six months (median length of follow up of three months) with captopril or placebo. Overall, the certainty of the evidence provided in this review was very low, since most risk of bias domains were judged to have either an unclear or a high risk of bias. Because of this, we are uncertain whether captopril makes any difference, in total urinary albumin excretion (at six months) as compared to the placebo group, although it yielded a mean difference of -49.00 (95% confidence interval (CI) -124.10 to 26.10) or in the absolute change score, although it yielded a mean difference of -63.00 (95% CI -93.78 to -32.22). At six months albumin excretion in the captopril group was noted to decrease from baseline by a mean (standard deviation) of 45 (23) mg/day and the placebo group was noted to increase by 18 (45) mg/day. Serum creatinine and potassium levels were reported constant throughout the study (very low-certainty evidence). The potential for inducing hypotension should be highlighted; the study reported a decrease of 8 mmHg in systolic pressure and 5 mmHg in diastolic and mean blood pressure (very low-certainty evidence).

AUTHORS' CONCLUSIONS

Overall, we judged the certainty of the evidence to be very low. The included study selectively reported its results, was not powered to detect a group difference, should it exist, and otherwise did not offer enough information to allow us to judge the bias inherent in the study. Indirectness (in relation to the limited age and type of population included) and imprecision (wide confidence intervals around the effect estimate) were observed. More long-term studies involving multiple centers and larger cohorts using a randomized-controlled design are warranted, especially among the pediatric age group. Detailed reporting of each outcome measure is necessary to allow a clear cut interpretation in a systematic review. One of the difficulties encountered in this review was the lack of detailed data reported in the included study. Overall, we judged the certainty of this evidence to be very low.

In Silico Analyses and Cytotoxicity Study of Asiaticoside and Asiatic Acid from Malaysian Plant as Potential mTOR Inhibitors

Natural products remain a popular alternative treatment for many ailments in various countries. This study aimed to screen for potential mammalian target of rapamycin (mTOR) inhibitors from Malaysian natural substance, using the Natural Product Discovery database, and to determine the IC₅₀ of the selected mTOR inhibitors against UMB1949 cell line. The crystallographic structure of the molecular target (mTOR) was obtained from Protein Data Bank, with Protein Data Bank (PDB) ID: 4DRI. Everolimus, an mTOR inhibitor, was used as a standard compound for the comparative analysis. Computational docking approach was performed, using AutoDock Vina (screening) and AutoDock 4.2.6 (analysis). Based on our analysis, asiaticoside and its derivative, asiatic acid, both from Centella asiatica, revealed optimum-binding affinities with mTOR that were comparable to our standard compound. The effect of asiaticoside and asiatic acid on mTOR inhibition was validated with UMB1949 cell line, and their IC₅₀ values were 300 and 60 µM, respectively, compared to everolimus (29.5 µM). Interestingly, this is the first study of asiaticoside and asiatic acid against tuberous sclerosis complex (TSC) disease model by targeting mTOR. These results, coupled with our in silico findings, should prompt further studies, to clarify the mode of action, safety, and efficacy of these compounds as mTOR inhibitors.

The role of mTOR signalling pathway in hypoxia-induced cognitive impairment

Hypoxia has been associated with cognitive impairment. Many studies have investigated the role of mTOR signalling pathway in cognitive functions but its role in hypoxia-induced cognitive impairment remains controversial. This review aimed to elucidate the role of mTOR in the mechanisms of cognitive impairment that may pave the way towards the mechanistic understanding and therapeutic intervention of hypoxia-induced cognitive impairment. mTORC1 is normally regulated during mild or acute hypoxic exposure giving rise to neuroprotection, whereas it is overactivated during severe or chronic hypoxia giving rise to neuronal cells death. Thus, it is worth exploring the possibility of maintaining normal mTORC1 activity and thereby preventing cognitive impairment during severe or chronic hypoxia.

Therapeutic Suppression of Nonsense Mutation: An Emerging Target in Multiple Diseases and Thrombotic Disorders

Nonsense mutations contribute to approximately 10-30% of the total human inherited diseases via disruption of protein translation. If any of the three termination codons (UGA, UAG and UAA) emerges prematurely [known as premature termination codon (PTC)] before the natural canonical stop codon, truncated nonfunctional proteins or proteins with deleterious loss or gain-of-function activities are synthesized, followed by the development of nonsense mutation-mediated diseases. In the past decade, PTC-associated diseases captured much attention in biomedical research, especially as molecular therapeutic targets via nonsense suppression (i.e. translational readthrough) regimens. In this review, we highlighted different treatment strategies of PTC targeting readthrough therapeutics including the use of aminoglycosides, ataluren (formerly known as PTC124), suppressor tRNAs, nonsense-mediated mRNA decay, pseudouridylation and CRISPR/Cas9 system to treat PTC-mediated diseases. In addition, as thrombotic disorders are a group of disease with major burdens worldwide, 19 potential genes containing a total of 705 PTCs that cause 21 thrombotic disorders have been listed based on the data reanalysis from the 'GeneCards® - Human Gene Database' and 'Human Gene Mutation Database' (HGMD®). These PTC-containing genes can be potential targets amenable for different readthrough therapeutic strategies in the future.

Antiphospholipid Antibody-Mediated Thrombotic Mechanisms in Antiphospholipid Syndrome: Towards Pathophysiology-Based Treatment

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by a persistently high titer of antiphospholipid antibodies (aPLs). In addition to pregnancy morbidity, arterial and/or venous thrombosis is another clinical feature of APS. Regardless of the type of APS, the thrombi formed by the induction of aPLs can lead to deep vein thrombosis, pulmonary embolism, myocardial infarction, stroke and gangrene. Although the concept of APS was introduced approximately 32 years ago, its thrombogenic pathophysiology is still unclear. Therefore, patients are treated with anticoagulant and/or antiplatelet regimens just as in other thrombotic disorders even though the thrombotic pathophysiology is mainly aPLs-mediated. In this review, we provided an update of the cellular, auto-immune and genetic factors known to play important roles in the generation of thrombi. Current successful regimens are also outlined along with potential emerging treatment strategies that may lead to the optimum management of thrombotic APS patients.

Type 2 Diabetes Mellitus and Alzheimer's Disease: Bridging the Pathophysiology and Management

Although type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) are two independent diseases, evidences from epidemiological, pathophysiological and animal studies have indicated a close pathophysiological relationship between these diseases. Due to the pathophysiological similarity of T2DM and AD, which includes insulin resistance and deficiency, protein aggregation, oxidative stress, inflammation, autophagocytosis and advanced glycation end products; AD is often referred to as "type 3 diabetes". In addition to the targeted regimens usually used for treating T2DM and AD individually, currently, anti-diabetic drugs are successfully used to reduce the cognitive decline in AD patients. Therefore, if a common pathophysiology of T2DM and AD could be clearly determined, both diseases could be managed more efficiently, possibly by shared pharmacotherapy in addition to understanding the broader spectrum of preventive strategies. The aim of this review is to discuss the pathophysiological bridge between T2DM and AD to lay the foundation for the future treatment strategies in the management of both diseases.

Natural Products Towards the Discovery of Potential Future Antithrombotic Drugs

Globally, thrombosis-associated disorders are one of the main contributors to fatalities. Besides genetic influences, there are some acquired and environmental risk factors dominating thrombotic diseases. Although standard regimens have been used for a long time, many side effects still occur which can be life threatening. Therefore, natural products are good alternatives. Although the quest for antithrombotic natural products came to light only since the end of last century, in the last two decades, a considerable number of natural products showing antithrombotic activities (antiplatelet, anticoagulant and fibrinolytic) with no or minimal side effects have been reported. In this review, several natural products used as antithrombotic agents including medicinal plants, vegetables, fruits, spices and edible mushrooms which have been discovered in the last 15 years and their target sites (thrombogenic components, factors and thrombotic pathways) are described. In addition, the side effects, limitations and interactions of standard regimens with natural products are also discussed. The active compounds could serve as potential sources for future research on antithrombotic drug development. As a future direction, more advanced researches (in quest of the target cofactor or component involved in antithrombotic pathways) are warranted for the development of potential natural antithrombotic medications (alone or combined with standard regimens) to ensure maximum safety and efficacy.

Placebo Controlled Trials: Interests of Subjects versus Interests of Drug Regulators

The use of placebo-controlled trials in situations where established therapies are available is considered ethically problematic since the patients randomised to the placebo group are deprived of the beneficial treatment. The pharmaceutical industry and drug regulators seem to argue that placebo-controlled trials with extensive precautions and control measures in place should still be allowed since they provide necessary scientific evidence for the efficacy and safety of new drugs. On the other hand, the scientific value and usefulness for clinical decision-making may be much higher if the new drug is compared directly to existing therapies. As such, it may still be unethical to impose the burden and risk of placebo-controlled trials on patients even if extensive precautions are taken. A few exceptions do exist. The use of placebo-controlled trials in situations where an established, effective and safe therapy exists remains largely controversial.

Presence of Anticardiolipin Antibodies in Patients with Dementia: A Systematic Review and Meta-Analysis

Growing evidences are supporting towards the involvement of antiphospholipid antibodies [aPLs e.g., lupus anticoagulant (LA), anticardiolipin (aCL) and anti-β2-glycoprotein I (anti-β2-GPI) antibodies] in various neurological manifestations including migraine, epilepsy and dementia in the presence or absence of autoimmune diseases such as antiphospholipid syndrome or systemic lupus erythematosus. The aim of this systematic review and meta-analysis was to assess the presence of aPLs in dementia patients without a diagnosis of any autoimmune disease. Electronic databases (e.g., PubMed, Web of Science, Scopus, ScienceDirect and Google Scholar) were searched without any year or language restrictions and based on the inclusion criteria, nine prospective case-control studies assessing only aCL were included involving 372 dementia patients and 337 healthy controls. No studies were found to assess the presence of both LA or anti-β2-GPI. The study-specific odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using random-effects model. We observed the prevalence of aCL in dementia was higher (32.80%) than that of controls (9.50%) e.g., 3.45 times higher risk of presenting with dementia than the controls, and significant presence of aCL antibodies was detected in dementia patients compared to controls (OR: 4.94, 95% CI: 2.66 - 9.16, p < 0.00001; I² = 32%, p = 0.16). Publication bias was not observed from Egger's (p = 0.081) and Begg's tests (p = 0.180). Based on the study quality assessment using modified Newcastle-Ottawa Scale for case-control studies, seven of nine studies were of high methodological quality scoring ≥ 7 (median value). In summary, aCL antibodies were significantly present in dementia patients suggesting that aCL antibodies are generated due to the autoimmune-derived effects of dementia or there might be a potential causative role of this autoantibody in dementia pathogenesis.

A 15-year single centre retrospective study of antiphospholipid syndrome patients from Northern Malaysia

BACKGROUND

Antiphospholipid syndrome (APS) is an autoimmune disorder characterised by thrombosis and/or pregnancy morbidity in the presence of antiphospholipid antibodies (aPLs) based on the Sydney criteria. We aimed to explore the clinico-laboratory features and treatment strategies of APS patients retrospectively.

METHODOLOGY

The medical records of APS patients registered under Hospital Universiti Sains Malaysia (Kelantan state) between 2000 and 2015 were reviewed.

RESULTS

A total of 17 APS subjects (age 40.7 ± 12.8 years) including 11 primary (64.7%) and six secondary APS (35.3%) patients were identified. The follow-up period was 9.5 ± 6.7 years with male:female ratio of 1.0:4.7. Pregnancy morbidity was the most common clinical manifestation (11/14; 78.6%) followed by recurrent venous thrombosis (10/17; 58.8%). For other clinical features, menorrhagia was the most frequently observed manifestation (4/14; 28.6%) followed by aPLs-associated thrombocytopenia (4/17; 23.5%) and ovarian cyst (3/14; 21.4%). LA and aCL were positive in 94.1% (16/17) and 81.8% (9/11) of the patients, respectively. APTT value (76.7 ± 17.0 sec) was significantly high (p < 0.05). Low intensity warfarin alone was successful to maintain target INR (2.0 - 3.0) and prevent recurrence of thrombosis.

CONCLUSION

The tendency of pregnancy morbidity in this cohort of Malaysian Kelantanese APS patients was high compared to other previously reported APS cohorts. Low intensity warfarin was successful in preventing recurrence of thrombosis, however, APS women receiving long-term anticoagulants should be monitored for possible occurrence of menorrhagia and ovarian cysts.

Familial primary antiphospholipid syndrome: A report of co-occurrence in three Malaysian family members

Here we present a case report of three familial primary antiphospholipid syndrome (PAPS) patients from Malaysia. The three familial patients comprised two females and one male with a mean age of 26.3 years. The first diagnosis was made between 2005 and 2009, and all patients demonstrated deep vein thrombosis, high levels of IgM and IgG anticardiolipin antibodies, and received warfarin treatment international normalized ratio (INR) 2.0-3.0. The patients ceased to show clinical symptoms after treatment. Recently (August 2014), we investigated whether the levels of antiphospholipid antibodies remained elevated, and we found that seronegativity occurred in the patients. We suspect that prolonged anticoagulant treatment might be one of the causes of reduced levels of antiphospholipid antibodies in these familial PAPS patients.

Informed Consent Template and Guidelines on the Ethical Practice in Human Genetics and Human Genomic Research; Initiatives of the Universiti Sains Malaysia

Malaysia is advancing and nearly on pace with the international scientific community in human genetics and human genomics research. However, this research poses unique challenges. Although Malaysia already regulates medical genetic services, these regulations are insufficient for coping with the ethical issues emerging from recent genomic technologies. The Universiti Sains Malaysia recently created in-house guidelines and an informed consent template for genetic and genomic research. This article presents these guidelines and the informed consent template and discusses the justification and the background of the initiative. We also propose recommendations pertaining to local social studies and regulatory arrangements.

Rapamycin and its analogues (rapalogs) for Tuberous Sclerosis Complex-associated tumors: a systematic review on non-randomized studies using meta-analysis

Background

Rapamycin has gained significant attention for its potential activity in reducing the size of TSC-associated tumors, thus providing alternative to surgery. This study aimed at determining the efficacy of rapamycin and rapalogs for reducing the size of TSC-associated solid tumors in patients with Tuberous Sclerosis Complex (TSC).

Methods

Our data sources included electronic searches of the PubMed. We included into our meta-analysis any type of non-randomized study that reported the use of rapamycin and rapalogs for reducing the size of TSC-associated solid tumors in patients with TSC. Data was entered into Cochrane Review Manager Version 5.3 and analyzed.

Results

Four case reports and 4 clinical trials were included. Five patients from the case reports (all with SEGA) and 91 patients from the clinical trials (41 with SEGA, 63 with kidney angiomyolipoma and 5 with liver angiomyolipoma) were included into the analysis. Volume and diameter of SEGAs were significantly reduced by mean difference of 1.23 cc (95 % CI −2.32 to −0.13; p = 0.03) and 7.91 mm (95 % CI −11.82 to −4.01; p < 0.0001), respectively. Volume and mean of sum of longest diameter of kidney angiomyolipomas were significantly reduced by mean difference of 39.5 cc (95 % CI −48.85 to −30.15; p <0.00001) and 69.03 mm (95 % CI −158.05 to 12.65; p = 0.008), respectively. In liver angiomyolipomas, however, reduction in tumor size was not evident. Sum of longest diameter of liver angiomyolipomas in 4 patients were enlarged by 2.7 mm (95 % CI 28.42 to −23.02) by the end of treatment, though not significant (p = 0.84).

Conclusions

Rapamycin and rapalogs showed efficacy towards reducing the size of SEGA and kidney angiomyolipoma but not liver angiomyolipomas. This finding is strengthening the conclusion of our Cochrane systematic review on the randomized trials.

Two novel gross deletions of TSC2 in Malaysian patients with tuberous sclerosis complex and TSC2/PKD1 contiguous deletion syndrome

Tuberous sclerosis complex is an autosomal dominant neurocutaneous disorder affecting multiple organs. Tuberous sclerosis complex is caused by mutation in either one of the two disease-causing genes, TSC1 or TSC2, encoding for hamartin and tuberin, respectively. TSC2/PKD1 contiguous gene deletion syndrome is a very rare condition due to deletion involving both TSC2 and PKD1 genes. Tuberous sclerosis complex cannot be easily diagnosed since there is no pathognomonic feature, although there are consensus diagnostic criteria for that. Mutation analysis is useful and plays important roles. We report here two novel gross deletions of TSC2 gene in Malay patients with tuberous sclerosis complex and TSC2/PKD1 contiguous gene deletion syndrome, respectively.

Histone deacetylase inhibitors as potential treatment for spinal muscular atrophy

Histone acetylation plays an important role in regulation of transcription in eukaryotic cells by promoting a more relaxed chromatin structure necessary for transcriptional activation. Histone deacetylases (HDACs) remove acetyl groups and suppress gene expression. HDAC inhibitors (HDACIs) are a group of small molecules that promote gene transcription by chromatin remodeling and have been extensively studied as potential drugs for treating of spinal muscular atrophy. Various drugs in this class have been studied with regard to their efficacy in increasing the expression of survival of motor neuron (SMN) protein. In this review, we discuss the current literature on this topic and summarize the findings of the main studies in this field.

Allele-specific PCR for a cost-effective & time-efficient diagnostic screening of spinal muscular atrophy

Background & objectives:

Genetic diagnosis of spinal muscular atrophy (SMA) is complicated by the presence of SMN2 gene as majority of SMA patients show absence or deletion of SMN1 gene. PCR may amplify both the genes non selectively in presence of high amount of DNA. We evaluated whether allele-specific PCR for diagnostic screening of SMA is reliable in the presence of high amount of genomic DNA, which is commonly used when performing diagnostic screening using restriction enzymes.

Methods:

A total of 126 blood DNA samples were tested in amounts ranging 80-200 ng, referred for the genetic diagnosis of SMA using both conventional PCR-RFLP and allele-specific PCR.

Results:

The results from both methods showed agreement. Further, allele-specific PCR was found to be a time-efficient and cost-effective method.

Interpretation & conclusions:

Our study demonstrated the accuracy of our allele-specific PCR and the results were comparable compatible with that of PCR-RFLP, indicating its practical application in SMA diagnostic screening.

Two closely spaced nonsense mutations in the DMD gene in a Malaysian family

In Duchenne muscular dystrophy (DMD), identification of one nonsense mutation in the DMD gene has been considered an endpoint of genetic diagnosis. Here, we identified two closely spaced nonsense mutations in the DMD gene. In a Malaysian DMD patient two nonsense mutations (p.234S>X and p.249Q>X, respectively) were identified within exon 8. The proband's mother carried both mutations on one allele. Multiple mutations may explain the occasional discrepancies between genotype and phenotype in dystrophinopathy.

Deletion analysis of SMN1 exon 7 alone may be necessary and sufficient for the diagnosis of spinal muscular atrophy

The authors suggest a simplification for the current molecular genetic testing of spinal muscular atrophy (SMA). Deletion analysis of SMN1 exon 7 alone may be necessary and sufficient for the diagnosis of SMA. It is based on sole contribution of survival motor neuron 1 (SMN1) exon 7 to SMA pathogenesis.

Screening of the LIX1 gene in Japanese and Malaysian patients with SMA and/or SMA-like disorder

BACKGROUND

The majority of spinal muscular atrophy (SMA) patients showed homozygous deletion or other mutations of SMN1. However, the genetic etiology of a significant number of SMA patients has not been clarified. Recently, mutation in the gene underlying cat SMA, limb expression 1 (LIX1), has been reported. Similarity in clinical and pathological features of cat and human SMA may give an insight into possible similarity of the genetic etiology.

PATIENTS AND METHODS

In this study, we screened for a mutation in LIX1 using direct DNA sequencing in our SMA and/or SMA-like patients who retained SMN1. A total of 33 patients were enrolled in this study, of which 22 were Japanese and 11 were Malaysians. All these patients possessed at least two copies of SMN1.

RESULTS

We did not identify any pathogenic mutations in the coding regions or splice sites of LIX1 in the patients. In addition, we described a polymorphism within LIX1 intron 3, c.387+107A>T. We found that A-allele is significantly more frequent in SMA patients compared to normal individuals.

CONCLUSION

Molecular genetic analysis of our SMA and/or SMA-like patients suggests that LIX1 is not associated with the development of their disorders. However, the number of patients analyzed in this study was very limited, and a larger study with bigger sample size is needed to confirm this result.

Combination of SMN2 copy number and NAIP deletion predicts disease severity in spinal muscular atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by mutations in the SMN1 gene. The SMN2 gene is highly homologous to SMN1 and has been reported to be correlated with severity of the disease. The clinical presentation of SMA varies from severe to mild, with three clinical subtypes (type I, type II, and type III) that are assigned according to age of onset and severity of the disease. Here, we aim to investigate the potential association between the number of copies of SMN2 and the deletion in the NAIP gene with the clinical severity of SMA in patients of Malaysian origin. Forty-two SMA patients (14 of type I, 20 type II, and 8 type III) carrying deletions of the SMN1 gene were enrolled in this study. SMN2 copy number was determined by fluorescence-based quantitative polymerase chain reaction assay. Twenty-nine percent of type I patients carried one copy of SMN2, while the remaining 71% carried two copies. Among the type II and type III SMA patients, 29% of cases carried two copies of the gene, while 71% carried three or four copies of SMN2. Deletion analysis of NAIP showed that 50% of type I SMA patients had a homozygous deletion of exon 5 of this gene and that only 10% of type II SMA cases carried a homozygous deletion, while all type III patients carried intact copies of the NAIP gene. We conclude that there exists a close relationship between SMN2 copy number and SMA disease severity, suggesting that the determination of SMN2 copy number may be a good predictor of SMA disease type. Furthermore, NAIP gene deletion was found to be associated with SMA severity. In conclusion, combining the analysis of deletion of NAIP with the assessment of SMN2 copy number increases the value of this tool in predicting the severity of SMA.

SMN2 and NAIP gene dosages in Vietnamese patients with spinal muscular atrophy

BACKGROUND

The SMN1 gene is now recognized as a spinal muscular atrophy (SMA)-causing gene, while SMN2 and NAIP have been characterized as a modifying factor of the clinical severity of SMA. Gene dosage of SMN2 is associated with clinical severity of SMA. But the relationship between gene dosage of NAIP and clinical severity of SMA remains to be clarified, although complete deletion of NAIP is frequent in type I patients.

METHODS

To evaluate the contribution of the SMN2 and NAIP gene dosages to SMA, quantitative real-time polymerase chain reaction was used to measure copy numbers of SMN2 and NAIP in 34 Vietnamese SMA patients lacking SMN1 (13 type I, 11 type II and 10 type III patients).

RESULTS

The SMN2 copy number in type I patients was significantly lower than that in type II-III patients, which was compatible with the previous reports. In contrast, 25 out of 34 patients had only zero or one copy of NAIP, while 50 out of 52 controls had two or more copies. For NAIP (+) genotype, six out of 13 type I patients, eight out of 11 type II patients and six out of 10 type III patients carried one NAIP copy.

CONCLUSIONS

The SMN2 copy number was related to the clinical severity of SMA among Vietnamese patients. The presence of one NAIP copy, that is, heterozygous NAIP deletion, was common in Vietnamese SMA, regardless of clinical phenotype.

Novel mutations in 21 patients with tuberous sclerosis complex and variation of tandem splice-acceptor sites in TSC1 exon 14

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by epilepsy, mental retardation, skin lesions, and tumors in various organs. However, TSC is sometimes difficult to diagnose because of its broad phenotypic spectrum. In such cases, it is essential to find a mutation in the disease-causing genes, TSC1 and TSC2. In this study, we analyzed 21 TSC patients from 16 families using a combination method of DHPLC and nucleotide sequencing. We identified 16 novel mutations in the 16 families: nine mutations in TSC1 (1 insertion, 7 deletion and 1 nonsense mutations) and seven mutations in TSC2 (2 insertion, 2 deletion, 1 missense mutations and 2 splicing abnormalities). We also tested the possibility of very short alternative splicing due to a variation of the tandem splice-acceptor sites of TSC1 exon 14 in a patient. RT-PCR and sequencing analysis indicated that no alternative splicing occurred in the patient. In conclusion, we confirmed the diagnosis of all patients using mutation analysis and clarified that variation of the tandem splice-acceptor sites in TSC1 exon 14 does not cause a splicing abnormality.

Hypomutability at the polyadenine tract in SMN intron 3 shows the invariability of the a-SMN protein structure

Recently, the axonal-SMN (a-SMN) protein, which is generated by the gene responsible for spinal muscular atrophy (SMA), SMN, has been reported. Surprisingly, the a-SMN transcript includes the entire sequence of SMN intron 3. We had expected a high frequency of insertion/deletion mutations at a polyadenine tract in this intron, since simple repetitive sequence motifs are prone to mutations. Such mutations could change the C-terminal structure of the a-SMN protein. However, our study showed that almost all individuals, including healthy individuals, SMA patients and SMA-like patients, carried only alleles with a normal polyadenine tract. Hypomutability of the polyadenine tract in SMN intron 3 suggests the existence of transcriptional mechanisms preventing alterations to the open reading frame of axonal SMN and not allowing variability in the protein structure of a-SMN.

A novel mutation at the N-terminal of SMN Tudor domain inhibits its interaction with target proteins

Although most patients with spinal muscular atrophy (SMA) are homozygous for deletion of the SMN1 gene, some patients bear one SMN1 copy with a subtle mutation. Detection of such an intragenic mutation may be helpful not only in confirming diagnosis but also in elucidating functional domains of the SMN protein. In this study, we identified a novel mutation in SMN1 of two Japanese patients with type I SMA. DHPLC and sequencing analysis revealed that they harbored a point mutation in SMN1 exon 3, 275G > C, leading to tryptophan-to-serine substitution at amino acid 92 (W92S) at the Nterminal of SMN Tudor domain. In-vitro protein binding assays showed that the mutation severely reduced interaction of the domain with SmB protein and fibrillarin, suggesting that it impairs the critical function of SMN. In conclusion, we reported here that a novel mutation, W92S, in the Tudor domain affects the interaction of SMN with the target proteins.

C117T variant in the SMN1 gene found in the Japanese population

BACKGROUND

The SMN genes are closely related to the development of spinal muscular atrophy (SMA); mutated SMN1 causes SMA and functional SMN2 modifies the severity of SMA. SMN1 and SMN2 are almost identical, being distinguished by only five base pair substitutions located at the 3'-end of the genes. Recently, a synonymous DNA variant, C117T, has been identified at the first codon of SMN2 exon 2a in the Caucasian population. It is still a question whether the variant is specific to the Caucasian population, and whether it is found only in SMN2. In order to address these questions, Japanese populations were screened for the presence of C117T in the SMN genes.

METHODS

To detect the C117T variant in a Japanese population, polymerase chain reaction-restriction fragment length polymorphism was performed in 33 SMA patients homozygous for SMN1 deletion and 106 control individuals. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to clarify whether the variant affects the splicing process of the SMN1 gene.

RESULTS

The C117T variant was found in one out of 33 Japanese SMA patients (3.0%) and in seven out of 106 Japanese control individuals (6.6%). There was no significant difference between frequencies in the present data and those reported from the Caucasian population. Notably, the C117T variant was also detected in the SMN1 gene; a control individual with homozygous SMN2 deletion was found to have the variant on one of the SMN1 genes. RT-PCR indicated that this variant of the SMN1 gene was normally transcribed and did not affect the splicing process in this individual.

CONCLUSIONS

The C117T variant was found not only in the Caucasian population, but also in the Japanese population. In addition, the variant was not specific to SMN2: it was also found in SMN1. RT-PCR indicated that the variant did not affect the splicing process.

Nonsense mutations of the ZFHX1B gene in two Japanese girls with Mowat-Wilson syndrome

Mowat-Wilson syndrome (MWS) is a multiple congenital anomaly-mental retardation complex caused by mutations in the Zinc Finger Homeobox 1 B gene (ZFHX1B). MWS has been reported in association with Hirschsprung disease (HSCR). MWS is sometimes difficult to diagnose clinically, especially when HSCR is absent. Thus, it is necessary to detect gene abnormalities at the molecular level. Here we report two Japanese girls with MWS, who showed a distinct facial phenotype, severe intellectual disability and epileptic seizures. Major congenital anomalies of the patients were very different. Patient 1 suffered from severe congenital heart disease, but did not show apparent HSCR. Patient 2 suffered from typical HSCR and underwent surgical treatment, but did not have congenital heart disease. According to the gene analysis using white blood cells, they had nonsense mutations in ZFHX1B, R695X and Q433X, respectively. In conclusion, molecular genetic analysis of ZFHX1B is important for a definite diagnosis of MWS which has a wide phenotypic spectrum of congenital anomalies.

ACE gene polymorphism in children with nephrotic syndrome in the Indonesian population

BACKGROUND

The angiotensin converting enzyme (ACE) gene carries insertion (I) and deletion (D) polymorphism within its intron 16. The presence of D-allele in the ACE gene has been reported as a probable genetic risk factor for idiopathic nephrotic syndrome (INS), especially the subtype of focal segmental glomerulosclerosis (FSGS). The D-allele may be related to poor responsiveness to steroid therapy. To clarify the relationship between the D-allele and INS, we studied the prevalence of the D-allele in the Javanese-Indonesian patients. Additionally, we also analyzed relationship between each genotype and steroid sensitivity among the MCNS patients.

METHODS

Eighty-five Javanese-Indonesian patients under 15 years of age with INS were enrolled in this study: 16 patients with FSGS and 69 patients with minimal change nephrotic syndrome (MCNS). As controls, 68 healthy adult Javanese-Indonesians with no history of kidney disease volunteered to participate in this study. Genotypes based on the polymorphisms (I/D) were determined by using a PCR method. As for the steroid responsiveness, the information of 14 out of 16 FSGS patient (87.5%) and 69 out of 69 MCNS patients (100%) was available.

RESULTS

The genotype frequencies in the FSGS patients were II 37% (6/16), ID 44% (7/16) and DD 19% (3/16), and the D-allele frequency was 41% (13/32). The genotype frequencies in the MCNS patients were II 56% (39/69), ID 38% (26/69) and DD 6% (4/69), and the D-allele frequency was 25% (34/138). The genotype frequencies in the controls were II 60% (41/68), ID 31% (21/68), and DD 9% (6/68), and the D-allele frequency was 26% (33/136). None of the FSGS patients were sensitive to steroid, while almost all MCNS patients (66/69) were sensitive to steroid. The genotype frequencies among steroid-sensitive MCNS patients were consistent with those of the controls, suggesting that there was no relationship between each genotype and steroid sensitivity.

CONCLUSIONS

In the Javanese-Indonesian population, none of the comparisons showed any significant differences in the genotypic distribution and allelic frequencies among the three groups, FSGS, MCNS and controls, although D-allele tended to exist more frequently in FSGS patients than in the MCNS patients and controls. In addition, the D-allele frequency was not related to steroid sensitivity in the MCNS patients.