MagicTouch PTA Sirolimus-Coated Balloon for Femoropopliteal and Below-the-Knee Disease: 3-Year Outcomes of the XTOSI Trial

BACKGROUND

Sirolimus-coated balloon (SCB) is a potential treatment option for peripheral arterial disease (PAD). There are currently no long-term clinical data for this novel treatment for PAD. We present the 3-year results of the first-in-human study of MagicTouch PTA SCB for treatment of PAD for both femoropopliteal and below-the-knee arteries.

METHODS

The XTOSI pilot study is a prospective, single-arm, open-label, single-center trial evaluating MagicTouch PTA SCB for symptomatic PAD. Assessments through 3 years included freedom from clinically driven target lesion revascularization (CD-TLR), freedom from major amputation, amputation-free survival (AFS), overall survival, and ulcer-free status.

RESULTS

At 3 years, the overall freedom from CD-TLR was 84.4%, freedom from major amputation was 86.1%, AFS was 63.3%, overall survival was 63.3%, and ulcer-free status in remaining survivors with intact limbs was 100%. For femoropopliteal lesions, at 3 years, the freedom from CD-TLR was 92.9%, freedom from major amputation was 93.3%, AFS was 70%, and overall survival was 70%. For below-the-knee lesions, at 3 years, the freedom from CD-TLR was 77.8%, freedom from major amputation was 81.0%, AFS was 58.6%, and overall survival was 58.6%.

CONCLUSIONS

SCB in the XTOSI pilot study showed promising clinical results sustained to 3 years, and no long-term safety concerns were raised. Randomized trials are currently ongoing to investigate the safety and efficacy of SCB for treatment of PAD.

Medium-Term Survival After Unrepaired Ruptured Abdominal Aortic Aneurysm

PURPOSE

Ruptured abdominal aortic aneurysm (AAA) is almost always considered fatal without open surgical or endovascular repair. We report a case that has defied this norm and explore the possible factors involved in this exceedingly rare outcome.

CASE REPORT

An 87 year old gentleman presented with an acute ruptured AAA with left retroperitoneal hematoma. He was counseled for emergent repair, but opted for conservative management instead. He has remained well at the time of writing, 13 months from the rupture, with clinical resolution of symptoms along with radiological resolution of the hematoma.

CONCLUSION

Timely repair remains the mainstay of management for ruptured AAA, although this rare case highlights that it is possible for ruptured AAA to seal spontaneously with patient surviving up to 13 months. We have sought to hypothesize the factors in this case that may have contributed to prolonged survival following untreated ruptured AAA.

CLINICAL IMPACT STATEMENT

While the overwhelming evidence is that a ruptured AAA left unrepaired is fatal, our case report illustrates a rare case that shows it is possible for ruptured AAA to seal spontaneously, with patient surviving up to 13 months. We seek to hypothesize the factors that may contribute to such prolonged survival.

A case of severe polyarteritis nodosa with critical limb threatening ischemia-promising treatment with sirolimus drug-coated angioplasty

Polyarteritis nodosa (PAN) is a rare form of vasculitis. Acute limb ischemia is a rare presentation and complication of PAN. Plain old balloon angioplasty (POBA) is one of the treatment strategies for addressing PAN-related critical limb threatening ischemia (CLTI). However, recurrence of stenosis and occlusion is frequent, making POBA a poor treatment choice, as evidenced in our described clinical case. Consequently, with consideration of sirolimus's anti-inflammatory and immunosuppressive properties, we used a sirolimus-coated balloon in the treatment of PAN-induced CLTI. A 37-year-old woman first presented with acute limb ischemia as her initial symptom. Diagnostic angiography demonstrated occlusion of her tibial vessels, and POBA was performed to restore perfusion. Later in the course of her illness, she developed foot gangrene despite multiple courses of immunosuppressive drugs and several attempts with POBA to achieve limb salvage. Because of her disease trajectory, a MagicTouch (Concept Medical) sirolimus-coated balloon was deployed to her anterior tibial artery during her third angioplasty. At 17 months after her last angioplasty, she remained ulcer free, and surveillance scans demonstrated occlusion-free tibial vessels. The use of sirolimus-coated balloon angioplasty is a promising treatment approach for successful limb salvage in patients with PAN vasculitis and CLTI.

Comparison of adhesive single-lead cardiac ECG patch device with Holter monitoring for detecting atrial fibrillation after an acute cerebral ischemic event: An interim analysis

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Health Malaysia

Background

Stroke secondary to atrial fibrillation (AF) is common and often associated with higher risk of stroke recurrence. Detection of AF is challenging due to brief unpredictable episodes of AF runs, especially in patients whose admission electrocardiogram (ECG) demonstrates a sinus rhythm. Probability of AF detection may be higher with early initiation of prolonged ECG monitoring.

Purpose

To compare diagnostic yield of 7-day cardiac ECG patch versus 24-hour Holter monitoring for detecting AF≥30 seconds; to identify predictors of AF in stroke patients; to determine if 7-day cardiac ECG patch results in a change in clinical practice.

Methods

In this investigator-initiated prospective study with pairwise comparison of 24-hour Holter and 7-day cardiac ECG patch monitoring, 150 patients who were admitted to a tertiary referral centre with acute ischemic stroke (AIS) or transient ischemic attack (TIA) within 1 week, without known AF, and had sinus rhythm in the admission 12-lead ECG were enrolled. Each patient underwent simultaneous 24-hour Holter and 7-day cardiac ECG patch monitoring. Routine transthoracic echocardiography was performed on each patient to assess cardiac function and exclude intracardiac thrombus.

Results

There were 102 (68.0%) male patients. 12 (8.0%) patients had underlying history of coronary artery disease; 26 (17.3%) had recurrent stroke or TIA. On admission, median NIH Stroke scale was 4; 18 (12.0%) patients had thrombolysis with alteplase. On transthoracic echocardiography, none had intracardiac thrombus.

Both Holter and cardiac ECG patch monitoring were initiated simultaneously at median 2 days after index stroke event. Of 150 patients, 17 (11.3%) detected AF ≥30 seconds. Of these 17 patients, 7 (4.7%) had AF detected within the first 24 hours on both Holter and cardiac ECG patch; 10 (6.7%) were detected after 24 hours on cardiac ECG patch only. Number needed to screen to detect one AF was 6. Compliance to 7-day cardiac ECG patch monitoring was 81.3%.

There was no significant difference in age among patients with and without AF. Although left atrium (LA) was not found to be dilated in patients with AF, LA volume index was significantly higher (28.3±15.9 vs 21.8±8.5, p=0.018) and LA emptying fraction (LAEF) was significantly lower (38.0%±30.2 vs 52.6%±16.7, p=0.007). The prolonged 7-day cardiac ECG monitoring patch resulted in 1.5-fold increase in prescription of anticoagulation therapy.

Conclusions

A 7-day cardiac ECG patch monitoring detected more patients with AF ≥30 seconds than 24-hour Holter monitoring and resulted in increase in prescription of anticoagulation therapy. Higher LA volume index and lower LA emptying fraction were predictors of AF in patients with a recent stroke.

Cleaner XT Rotational Thrombectomy: An Efficacious Endovascular Technique for Salvage of Thrombosed Arteriovenous Access and a 12 Month Outcome Analysis

Purpose:

This study aims to describe an efficacious method using Cleaner XT rotational thrombectomy with catheter-directed thrombolysis and drug-eluting balloon angioplasty for the salvage of thrombosed arteriovenous fistulae and grafts.

Materials and Methods:

Retrospective analysis of all patients with thrombosed hemodialysis accesses who underwent endovascular salvage using the Cleaner XT rotational thrombectomy system at a single institution between June 2019 and September 2020 was performed. Patency was presented as Kaplan-Meier survival curves, and regression analysis was performed to examine predictors of postintervention primary patency and assisted primary patency based on Cox proportional-hazards model.

Results:

Thirty-four patients with thrombosed accesses underwent Cleaner XT rotational thrombectomy between June 2019 and September 2020. Technical and clinical success were both 100%. Mean procedure time was 62 ± 20 minutes. Mean postintervention primary patency time was 152 ± 51 days; 30, 90, 180, and 365 day postintervention primary patency rates were 89%, 80%, 68%, and 56%, respectively. Mean postintervention-assisted primary patency time was 157 ± 59 days; 30, 90, 180, and 365 day postintervention-assisted primary patency rates were 91%, 82%, 71%, and 59%, and 180 and 365 day secondary patency rates were 97.2% and 94.4%, respectively.

Conclusion:

The Cleaner XT rotational thrombectomy device demonstrates excellent clinical and technical success rates, with good patency results at all time points up to 12 months postintervention.

SIroliMus coated angioPlasty versus plain balloon angioplasty in the tREatment of dialySis acceSs dysfunctION (IMPRESSION): study protocol for a randomized controlled trial

Background

Percutaneous transluminal angioplasty is the current standard treatment for arteriovenous fistula (AVF) stenosis. The mid- and long-term patency with plain balloon angioplasty (PBA) is however far from satisfactory. While paclitaxel-coated balloon angioplasty has been shown to be superior to PBA, concern over its safety profile has recently arisen after a reported possible increased mortality risk with a meta-analysis of large lower limb studies. An angioplasty balloon with a new type of drug coating, the sirolimus-coated balloon (SCB), has been proven to improve patency in the coronary arteries. However, its effect on AV access has yet to be studied.

Methods/design

This is an investigator-initiated, prospective, multicenter, double-blinded, randomized controlled clinical trial to assess the effectiveness of SCB compared to PBA in improving the patency of AVF after angioplasty. A total of 170 patients with mature AVF that requires PTA due to AVF dysfunction will be randomly assigned to treatment with a SCB or PBA at a 1:1 ratio, stratified by location of AVF and followed up for up to 1 year. The inclusion criteria include [1] adult patient aged 21 to 85 years who requires balloon angioplasty for dysfunctional arteriovenous fistula [2]; matured AVF, defined as being in use for at least 1 month prior to the angioplasty; and [3] successful angioplasty of the underlying stenosis with PBA, defined as less than 30% residual stenosis on digital subtraction angiography (DSA) and restoration of thrill in the AVF on clinical examination. The exclusion criteria include thrombosed or partially thrombosed access circuit at the time of treatment, presence of symptomatic or angiographically significant central vein stenosis that requires treatment with more than 30% residual stenosis post angioplasty, and existing stent placement within the AVF circuit. The primary endpoint of the study is access circuit primary patency at 6 months. The secondary endpoints are target lesion primary patency; access circuit-assisted primary patency; access circuit secondary patency at 3, 6, and 12 months; target lesion restenosis rate at 6 months; total number of interventions; complication rate; and cost-effectiveness. The trial is supported by Concept Medical.

Discussion

This study will evaluate the clinical efficacy and safety of SCB compared to PBA in the treatment of AVF stenosis in hemodialysis patients.

Trial registration

ClinicalTrials.govNCT04409912. Registered on 1 June 2020

MagicTouch PTA Sirolimus Coated Balloon for Femoropopliteal and Below the Knee Disease: Results From XTOSI Pilot Study Up To 12 Months

INTRODUCTION

Sirolimus coated balloon (SCB) is a promising treatment option to prevent restenosis for peripheral arterial occlusive disease (PAOD). This is a pilot first-in-human study of MagicTouch percutaneous transluminal angioplasty (PTA) SCB for treatment of PAOD for both femoropopliteal and below the knee arteries (BTK).

MATERIAL AND METHODS

Xtreme Touch-Neo [MagicTouch PTA] Sirolimus Coated Balloon (XTOSI) pilot study is a prospective, single-arm, open-label, single-center trial evaluating MagicTouch PTA SCB for symptomatic PAOD. Primary endpoint was defined as primary patency at 6 months (duplex ultrasound peak systolic velocity ratio ≤2.4). Secondary endpoints included clinically driven target lesion revascularization (CD-TLR), amputation free survival (AFS), all-cause mortality, and limb salvage success.

RESULTS

Fifty patients were recruited. The mean age was 67 (n=31 [62%] males). SCB was applied to femoropopliteal in 20 patients (40%) and BTK in 30 patients (60%). Majority of treatments (94%) were performed for limb salvage indications (Rutherford scores 5 or 6). This was a high risk cohort, in which 90% had diabetes, 36% had coronary artery disease, 20% had end stage renal failure, and American Society of Anaesthesiologists (ASA) score was 3 or more in 80%. Mean lesion length treated was 227±81 mm, of which 36% were total occlusions. Technical and device success were both 100%. At 30 days, mortality was 2% and major limb amputation was also 2%. Six-month primary patency was 80% (88.2% for femoropopliteal; 74% for BTK). At 12 months, freedom from CD-TLR was 89.7% (94.1% for femoropopliteal; 86.3% for BTK), AFS was 81.6% (90.0% for femoropopliteal; 75.9% for BTK), all-cause mortality was 14.3% (10.0% for femoropopliteal; 17.2% for BTK), and limb salvage success was 92.9% (94.4% for femoropopliteal; 91.7% for BTK). There was a statistically significant increase between baseline and 6-month toe pressures for both femoropopliteal (57.3±23.3 mm Hg vs 82.5±37.8 mm Hg; p<.001) and BTK lesions (52.8±19.2 mm Hg vs 70.7±37 mm Hg; p<.037). At 12 months, wound healing rate was 33/39 (84.6%).

CONCLUSIONS

MagicTouch PTA SCB in the XTOSI study showed promising 6-month primary patency and encouraging 12-month freedom from CD-TLR, AFS, and limb salvage rates. No early safety concerns were raised. Randomized trials are needed to investigate the safety and efficacy of SCB for treatment of PAOD.

Endovascular retrograde recanalization in Asian critical limb ischaemia patients

BACKGROUND

To evaluate endovascular retrograde recanalization of critical limb ischaemia (CLI) patients with chronic total occlusions (CTOs) in an Asian population.

METHODS

We conducted a single centre-based retrospective review of CLI patients with CTOs who had undergone endovascular retrograde recanalization using the subintimal arterial flossing with antegrade-retrograde intervention technique.

RESULTS

A total of 40 CLI patients with CTOs underwent endovascular intervention. The median age was 71 years; 67.5% were males and Chinese accounted for 65% of the patients, of which 55% were in Rutherford category 6, 37.5% in category 5 and 7.5% in category 4. Antegrade-retrograde access was performed via the femoral artery in 39 cases and the brachial artery in one case for the proximal puncture, and the following arteries for the distal puncture: superficial femoral, n = 4 (10%); popliteal, n = 4 (10%); anterior tibial, n = 12 (30%); dorsalis pedis, n = 9 (22.5%); peroneal, n = 4 (10%) and posterior tibial, n = 7 (17.5%). Technical success was high at 92.5% (n = 37). After intervention, 25% (n = 10) had below-knee triple vessel runoff, 52.5% (n = 21) had double vessel runoff and 15.0% (n = 6) had single vessel runoff. Stenting for target vessel dissections was required in 12 patients. There were two cases of significant bleeding; one common femoral artery pseudoaneurysm was treated with ultrasound-guided thrombin injection and another case of distal puncture site bleeding only required compression. Limb salvage at 1 year was 92.5% (n = 37).

CONCLUSION

The subintimal arterial flossing with antegrade-retrograde intervention technique is safe with high technical success rates and acceptable outcomes in Asian CLI patients with CTOs.

Influence of apolipoprotein B signal peptide insertion/deletion polymorphism on serum lipids and apolipoproteins in a Chinese population

Insertion/deletion polymorphism of the apo B gene encoding signal peptide and its influence on serum lipids and apolipoproteins was studied in 269 Chinese of both sexes in Singapore. The frequency of the Del allele was found to be 0.20, which is significantly lower than that in Caucasians (France) (0.34). The distribution of genotypes of ins/del polymorphism was at Hardy-Weinberg equilibrium in this population. There was an excess of individuals with the deletion allele in hypercholesterolemic subjects compared to those with normal cholesterol levels (P less than 0.05). All the lipid and apolipoprotein values were regressed for age, sex and BMI by multiple regression analysis. Individuals with one or two del alleles had significantly higher levels of serum total cholesterol (248.8 +/- 13.0 and 255.4 +/- 20.4 mg/dl, respectively) compared to those in individuals with only the Ins allele (218.4 +/- 7.8 mg/dl) (P less than 0.05). Serum LDL cholesterol level was also significantly higher in individuals with del allele (173.4 +/- 11.7 mg/dl) compared to that in those without the del allele (141.1 +/- 7.4 mg/dl) (P = 0.02). The percentages of sample variance of different lipid traits explained by apo B signal peptide polymorphism were estimated by analysis of variance (ANOVA) with sex, age and BMI as covariates. 2.3% of variability of serum total cholesterol (F = 3.27, P = 0.040) and 2.8% of LDL cholesterol (F = 3.87, P = 0.023) could be explained by the ins/del polymorphism of the apo B signal peptide gene.

Apolipoprotein B-gene DNA polymorphisms (Xbal andEcoRI), serum lipids, and apolipoproteins in healthy Chinese

The frequency of restriction fragment length polymorphisms (RFLPs) of the apolipoprotein B (apo B) gene, detected by XbaI and EcoRI, and their influence on serum lipids and apolipoproteins were studied in healthy Chinese of both sexes in Singapore. A total of 221 subjects (150 males, 71 females) were investigated for the XbaI and 159 subjects for the EcoRI polymorphisms, while serum lipids and apolipoprotein levels were available for 196 subjects. The frequency of the X2 allele was found to be significantly lower in the Chinese than that reported in Caucasians from the United Kingdom (0.09 vs. 0.51, P less than 0.001). The haplotype frequencies were also significantly different between the Chinese and Caucasians with a higher frequency of X1R1 in the former compared to the latter (0.85 vs. 0.34, P less than 0.0001). The distribution of RFLP genotypes at both of the restriction sites was at Hardy-Weinberg equilibrium in all groups. The influence of the apo B RFLPs on serum lipids and apolipoprotein levels (apo AI, AII, and B) was studied by both residual and multiple regression analyses considering age, sex, body mass index (BMI), and genotypes as independent variables in all possible combinations. No association was observed between the apo B genotypes and serum lipids or apolipoprotein levels except for high density lipoprotein cholesterol (HDLC), apo AI and AII, with the X2 being associated with significantly lower levels of HDLC as well as apo AI and AII, the effect being stronger in males. These data raise the possibility that the mechanism of reported association between apo B polymorphism and coronary artery disease may be through effects on HDLC.

Influence of PvuII (intron 6) polymorphism of the lipoprotein lipase gene on cord plasma lipid and apolipoprotein levels in Indian and Chinese newborns of Singapore

The influence of the PvuII polymorphism (intron 6) of the lipoprotein lipase (LPL) gene on cord plasma lipid traits was studied in 252 ethnic Chinese and 240 ethnic Indian newborns of Singapore. The allelic frequencies of P+ (presence of the restriction site) were 0.67 and 0.56 in the Chinese and Indian newborns, respectively, similar to their respective adult populations. The genotype distributions at the PvuII site were at Hardy Weinberg equilibrium in both ethnic Chinese (chi2 = 2.0) and ethnic Indians (chi2 = 3.6). Cord blood HDL-cholesterol (HDL-C) levels are higher in newborn Chinese than newborn Indians. In addition, cord blood LDL-cholesterol (LDL-C), apoB, and lipoprotein(a) levels are lower in newborn Chinese than newborn Indians. Both newborn Chinese and Indian male homozygotes for P- allele have higher cord blood LDL-C levels than newborns with the more common P+P+ or P-P+ genotypes. In Chinese male newborns, the LDL-C levels were 0.76 +/- 0.61 mmol/L, 0.53 +/- 0.29 mmol/L and 0.46 +/- 0.25 mmol/L, respectively (p = 0.01). In Indian male newborns, the LDL-C levels were 0.88 +/- 0.35 mmol/L for the P-P- genotype and 0.65 +/- 0.24 mmol/L for the P+P+ genotype (p = 0.003). In addition, the influence of the P- allele on LDL-C levels is remarkably similar in both ethnic groups, accounting for 8.48% of the population variance in the Chinese newborns and 8.09% in the Indian newborns. In contrast, no obvious effect of genotype is seen in this lipid parameter in the newborn females of either ethnic groups. There is presence of significant genotype specific influence on the LDL-C levels in cord plasma in male newborns, suggesting an early expression of the LPL gene locus.

Malignant eccrine spiradenoma. Case report and review of the literature

Malignant eccrine spiradenoma is an exceedingly rare tumor. A case of a 72-year-old women with this highly aggressive malignancy arising from a long-standing lower leg lesion is reported. Management during the course of disease included surgery, radiation therapy (RT), hyperthermic limb perfusion chemotherapy, and chemotherapy. The patient died of her disease, with widespread metastatic disease 20 months after the diagnosis. A review of the literature is presented, and treatment considerations are summarized.

Plasma lipids and lipoprotein(a) levels in the Chinese from China and Singapore

This study compared the influence of environmental factors on plasma lipid levels between the descendants of immigrant southern Han Chinese (Singapore Chinese, n = 275) and the native Chinese from southern China (n = 277). Their lipid profiles including lipoprotein (a) [Lp(a)] were measured and compared. The alpha level was set at 0.05 throughout the analysis. Body mass index (BMI), plasma total cholesterol (TC), low density lipoprotein cholesterol (LDLC), high density lipoprotein cholesterol (HDLC) and triglycerides (TG) levels were significantly elevated in the Singapore Chinese. Plasma Lp(a) however, was comparable in both groups for concentrations as well as frequency distributions. Since both groups were genetically identical, the similar Lp(a) level was in agreement with studies which reported that the apolipoprotein(a) [apo(a)] gene explained as much as 70% of the plasma Lp(a) variations in Chinese. No correlation of plasma Lp(a) level was observed with age and BMI while significant positive linear correlations were observed with TC and LDLC in the male subjects only. We concluded that environmental factors (possibly affluent lifestyle and westernised diet) have significantly influenced the lipid risk factor levels of the Singapore Chinese whereas Lp(a) levels, which are predominantly under genetic control, were not altered significantly.

Ethnic variation of cord plasma apolipoprotein levels in relation to coronary risk level: a study in three ethnic groups of Singapore

In multiracial Singapore, the prevalence of coronary artery disease is highest in ethnic Indian and lowest in ethnic Chinese populations. Since susceptibility to coronary artery disease is closely associated with plasma lipid traits, we studied the cord blood lipid and apolipoprotein profiles of the three ethnic groups in Singapore to determine if ethnic differences in lipid profile are present at birth. The high-risk lipid traits of high LDL-cholesterol, triglycerides and apo B, low HDL-cholesterol and apo A-I were found to be highest in ethnic Indian and lowest in ethnic Chinese populations. This difference was concordant with the relative coronary mortality rates for their respective adult populations in Singapore.

Transcatheter embolization of coronary artery fistula with controlled release coils

The treatment for large congenital coronary cameral fistulas has been surgical but with advances in interventional catheterization techniques transcatheter embolization of these fistulas with coils or detachable balloons is now possible. This report describes occlusion of a congenital coronary arteriovenous fistula in a 6-year-old girl.

Racial variation of cord plasma lipoprotein(a) levels in relation to coronary risk level: a study in three ethnic groups in Singapore

Lipoprotein(a) [Lp(a)] is recognized as an independent risk factor for atherosclerosis. Studies have also shown that there are racial differences in the Lp(a) profile. The multiracial population of Singapore has demonstrated a differential prevalence of coronary artery disease, which is concordant with the plasma Lp(a) profile in the adult populations of Singapore. The level of Lp(a) is under strict genetic control, and its plasma concentration is determined significantly by inheritance. Expression of the racial profile of Lp(a) at birth was studied in the cord blood of 542 male and 468 female newborns from three ethnic groups of Singapore using the sandwich-ELISA. The Lp(a) levels were then related to the coronary risk levels of their respective adult populations. Lp(a) levels in Singapore newborns were found to be independent of the infant's birth weight and sex but were significantly influenced by race. Indian newborns had significantly higher plasma levels of Lp(a). Chinese newborns had the lowest Lp(a) levels at birth. The ranking of Lp(a) levels at birth was concordant with the relative coronary mortality rates for the respective adult populations of Singapore. Racial differences in plasma Lp(a) levels are present and expressed at birth.

Lack of association of angiotensin-converting enzyme (ACE). Gene insertion/deletion polymorphism with CAD in two Asian populations

Association of the insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene with coronary artery disease with or without myocardial infarction (MI) was examined in a group of Chinese and Indian men in Singapore. The sample comprised an angiographically confirmed patient group of 276 Chinese and 102 Indians, of which 155 Chinese and 72 Indians had MI, and a matched healthy control group (147 Chinese and 166 Indians). The frequency of the D allele in the Chinese was 0.39 in those with CAD with MI, 0.43 in those with CAD but without MI, and 0.41 in the control group. The frequency of the D allele in Indians was 0.44 in CAD with or without MI, and 0.45 in the control group. There was no significant association of the ACE gene with CAD or MI in the Chinese or Indians, either in the entire sample or in different risk groups. The frequency of the D allele was significantly lower in the healthy Chinese and Indians than that reported in Caucasians. The association of the ACE gene with MI or CAD observed in other studies could not be confirmed in the present series of Chinese and Indians in Singapore.

T cell receptor beta chain RFLP in Chinese, Indians and Malays from Singapore

Restriction fragment length polymorphism (RFLP) of the gene encoding the beta chain of the human T cell receptor (TcR) was studied in three ethnic groups in Singapore by Southern blotting. Polymorphism in the beta chain gene was identified in BglII-digested DNA samples using a 770-bp TcR beta cDNA clone containing the joining and constant region segments. The TcR beta/BglII polymorphism was studied in 136 Chinese, 93 Indian and 88 Malay samples. The frequency of the less frequent allele (TcR beta*2) in all the ethnic groups was significantly lower (0.15-0.29, p < 0.01) than that in the Caucasians (0.46). Indians had a significantly lower frequency of this allele (0.15) than the Chinese (0.29) and Malays (0.26).

Glucose-6-phosphate dehydrogenase deficiency in Singapore

Glucose-6-phosphate dehydrogenase (G6PD) in man is an X-linked enzyme. The deficiency of this enzyme is one of the most common inherited metabolic disorders in man. In Singapore, three clinical syndromes associated with G6PD deficiency had been described: severe haemolysis in neonates with kernicterus, haemoglobinuria and "viral hepatitis"-like syndrome. The human G6PD monomer consists of 515 amino acids. Only the tetrameric or dimeric forms composed of a single type subunit are catylitically active. The complete amino acid sequence of G6PD had been elucidated in man and various other animals. The region of high homology among the enzymes of various animals is presumably functionally active. Among the Chinese in Singapore, three common molecular variants had been identified: Canton (nt 1376 G --> T), Kaiping (nt 1388 G --> A) and Mediterranean (nt 563 C --> T) in frequencies of 24%, 21% and 10% respectively. In addition, two common mutants (Gaozhou, nt 95 A --> G and Chinese 5, nt 1024 C --> T) have been detected in Singapore Chinese in low frequencies. In Malays, 6 different deficient variants are known in Singapore (3 new, 1 Mahidol, 1 Indonesian and 1 Mediterranean).

Molecular diagnosis of Duchenne muscular dystrophy in Singapore

Duchenne muscular dystrophy (DMD) is a common lethal sex-linked recessive disorder. Seventy percent of the cases are inherited and 30% are due to mutations. The mainstay of prevention is detection of female carriers and antenatal diagnosis of affected foetuses. Before the era of molecular diagnosis, DMD has been clinically defined. Serum creatine kinase (CK) has also been used to screen women at risk for carrier status. With the isolation and sequencing of the DMD gene at Xp21 and the identification of the DMD gene-product dystrophin, DNA technology can be applied for the diagnosis of the affected, for the detection of carriers and in antenatal diagnosis. The multiplex polymerase chain reaction (PCR) technique offers a rapid and simple screening method for deletions of the gene. We were able to detect partial deletions which account for 58.3% of gene defects in our patients. This direct demonstration of the gene defect that causes DMD gives a 100% assurance of accuracy and specificity of the diagnosis. Linkage analysis is especially useful for prenatal diagnosis and carrier detection in the remaining 41.7% of families without detectable deletions or duplications. This approach however is indirect and is dependent on information on genotypes from affected males and key family members. With the availability of increasingly more restriction fragment length polymorphisms (RFLPs), it has become practical to use the haplotype method for accurate carrier detection and prenatal diagnosis.

Molecular variants of red cell glucose-6-phosphate dehydrogenase deficiency in Central Java, Indonesia

One hundred and sixty-nine Javanese males were screened for the presence of red cell glucose-6-phosphate dehydrogenase (G6PD) variants by a dye decoloration screening test and starch gel electrophoresis. The frequency of G6PD deficiency was 14%. Three non-deficient electrophoretic variants with mobilities of 95, 105 and 107% of GdB+ were encountered. Sixteen G6PD-deficient subjects were further investigated for the presence of mutations at nt95 A-->G, nt487 G-->A, nt493 A-->G, nt563 C-->T, nt1024 C-->T, nt1376 G-->T, nt1388 G-->A and the silent mutation (nt1311 C-->T) of the G6PD gene by natural or artificially created amplified restriction sites. They were identified by the polymerase chain reaction and electrophoresis of restriction-digested products. Five subjects had the Mediterranean mutation (nt563 C-->T), but only one had simultaneous presence of nt1311(T). The next common mutations were 1376(T) in three subjects and 487(A) in two subjects. Five of the sixteen subjects had the nt1311(T) mutation giving an overall frequency of 0.31. The other four mutations were absent in this population sample.

Five restriction fragment length polymorphisms of the APOA1-C3 gene and their influence on lipids and apolipoproteins in healthy Chinese

The distribution of five restriction fragment length polymorphisms (RFLPs) of the APOA1-C3 gene cluster and their influence on serum lipids and apolipoprotein levels was investigated in 151 healthy Chinese of both sexes. The frequencies of the rare alleles at ApaI, BanI, XmnI (A1) and SstI (C3) sites were significantly different in the Chinese when compared to Caucasians as follows: ApaI: 0.25 vs. 0.42 (p < 0.02); BanI: 0.33 vs. 0.16 (p < 0.01); XmnI: X2, 0.30 vs. 0.14, and X3, 0.08 vs 0.05 (p = 0.001); SstI (C3): 0.23 vs. 0.12 (p = 0.011). The frequency of P2 (PstI) at 0.04 was similar to that in Caucasians (0.07). The distribution of the genotypes of all the RFLPs was in Hardy-Weinberg equilibrium in this population. A significant association of the SstI polymorphism of the C3 region with the serum high-density lipoprotein (HDL)-cholesterol level was observed in both men and women, the rarer allele (S2) being associated with higher levels (p < 0.05). 5.8% of the sample variance of the HDL-cholesterol level in this sample could be explained by the SstI polymorphism of the C3 region (F = 6.07, p = 0.003). The association of the SstI locus with serum HDL-cholesterol was stronger in males than in females (R2 = 13.8 and 6.7%, respectively). There was a similar trend of association of the serum apolipoprotein A-I level with the SstI polymorphism, though it did not reach statistical significance. There was no association between the levels of any of the lipid and apolipoproteins studied with RFLPs of the APOA1 gene.

Molecular genetics of Wilms' tumour

Wilms' tumour, or nephroblastoma, is an embryonal malignancy of the kidney with an incidence of approximately 1 in 10,000 live births. It occurs in both sporadic and familial forms, but only 1% of Wilms' tumour patients have a positive family history. The molecular genetics of Wilms' tumour have been the subject of extensive research and at least three genes (WT1, WT2, WT3) have been implicated. WT1 has been mapped to 11p13, and it has been suggested that loss or inactivation of a tumour-suppressor gene at 11p13 might be a primary event in the development of Wilms' tumour. The WT2 gene maps to 11p15 in the region of the Beckwith-Wiedemann locus. The WT3 locus is likely to be located to chromosome 16q. The understanding of the molecular genetics of Wilms' tumour is reviewed briefly.

Lack of association of apolipoprotein E polymorphism with plasma Lp(a) levels in the Chinese

Apolipoprotein E (apoE) polymorphism and its influence on plasma lipids, lipoproteins, lipoprotein (a) [Lp(a)] and apolipoproteins was studied in 536 (270 males and 266 females) healthy Chinese in Singapore. From analysis of variance with age and BMI as covariates, apoE genotype was found to exert a significant influence on plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and apoB in females. Its effect in males was marginally significant only on LDL-C. In both sexes, plasma TC, LDL-C and apoB were lower in those who were E2-3 than in those who were E3-3. There was no significant difference in log-transformed Lp(a) level between the apoE genotypes after adjusting for the confounding effect of LDL-C in addition to age and BMI. The percentage variance (R2 x 100) of the lipid traits explained by apoE polymorphism in the females was 4.94% for plasma TC, 5.85% for LDL-C and 4.25% for apoB. We conclude that: 1) epsilon 2 allele had a lowering effect on plasma TC, LDL-C and apoB; 2) apoE polymorphism did not have any significant influence on Lp(a) concentration; and 3) the effect of apoE polymorphism on plasma TC, LDL-C and apoB was gender-specific, with a stronger influence in females than in males.

Racial variation of factor VII activity and antigen levels and their correlates in healthy Chinese and Indians at low and high risk for coronary artery disease

Plasma factor VII activity (FVIIc) is one of the independent risk factors of coronary artery disease (CAD) and is controlled by both genetic and environmental factors. South Asians including Indians have one of the highest prevalence and mortality rates from CAD while the Chinese have a much lower risk. Generally accepted risk factors cannot explain the high mortality from CAD in Indians. We examined two hundred and seventy seven Chinese (124 m, 153 f); and 216 healthy Indian (150 m, 66 f) adults for serum lipids; plasma FVIIc and FVIIag levels in order to examine racial variations of these and their correlates in these two populations. Both Indian men and women had significantly higher FVIIc levels (12% and 11%, respectively) than the Chinese even after adjustments of age, BMI and lipids (P < 0.01). In contrast, Indians had significantly lower plasma FVIIag levels than Chinese (8% and 9%, respectively in men and women; P < 0.01). Multiple linear regression analysis shows a strong correlation of FVIIc with serum triglycerides accounting for 4-8% of the total variability of FVIIc in different groups. Further, there was a stronger correlation between FVIIc and FVIIag in Indians than that in the Chinese (0.43 vs. 25) suggesting a greater activation resulting in higher FVIIc in Indians inspite of lower FVIIag levels. The higher FVIIc and stronger activation by triglycerides observed in this study partly explain the higher risk of CAD in Indians.

Biochemical characteristics of four common molecular variants in glucose-6-phosphate dehydrogenase-deficient Chinese in Singapore

Biochemical characteristics were determined for four common molecular variants of glucose-6-phosphate dehydrogenase (G6PD) deficiency and 10 non-deficient Chinese males in Singapore. The variants included one Mediterranean (nt563 C-->T), two Canton (G-->T at nt1376) and one each of Kaiping (1388 G-->A) and Chinese-5 (1024 C-->T) variants. Molecular identification was carried out by amplication of genomic DNA with specific oligonucleotide primers followed by digestion with restriction enzymes that recognize artificially created or naturally occurring restriction sites. All the variants had low enzyme activity in red cells (0.2-0.6 IU/g Hb). All but the Chinese-5 variant (nt1024) had a normal Km for NADP (7-10 microM). The Mediterranean variant had a high utilization of deamino-NADP (296%), followed by the Canton variant 1376 substitution (131%). The Km for glucose-6-phosphate was low in the Mediterranean and 1376 variant (18-40 microM) but high in the 1024 substitution (104 microM). Electrophoretic mobility in TEB buffer (pH 8.6) was slightly faster (103%) for the 1376 mutation while 100% for all the others. All but the 1024 substitution had increased analogue utilization for galactose-6-phosphate and 2-deoxy-glucose-6-phosphate (58 and 68% for the Mediterranean mutation and 14-23% for the 1376 and 1388 substitutions, respectively), and reduced heat stability.

Linkage disequilibrium between two loci (5' untranslated exon 1 and intron 5-DdeI) of the antithrombin III gene in three ethnic groups in Singapore

The distribution of two common DNA polymorphisms (5' untranslated exon 1 and intron 5-DdeI) of the antithrombin III (ATIII) gene was studied in three ethnic groups in Singapore: 251 Chinese, 221 Dravidian Indians and 102 Malays. The polymorphisms were identified by the polymerase chain reaction and size fractionation in agarose gels. The 5' untranslated to exon 1 polymorphism is a length polymorphism while the intron 5 polymorphism is a restriction site (DdeI) polymorphism. The frequency of the short fragment (S) of the 5' to exon 1 length polymorphism of the ATIII gene was found to be 0.37 in the Chinese, 0.54 in the Malays and 0.65 in the Dravidian Indians. For the Chinese, this was significantly lower compared to the Caucasians and Indians (p < 0.0001) and the Malays (p < 0.01). On the other hand, the frequencies of DdeI+ did not vary significantly among these three populations (p > 0.05). The distribution of different genotypes at these two loci of the ATIII gene was in Hardy-Weinberg equilibrium in all three ethnic groups. A strong linkage disequilibrium between these two polymorphisms was observed in all the ethnic groups and the estimated correlation coefficient (delta) was 0.42 in the Chinese (p < 0.001), 0.61 in the Dravidian Indians (p < 0.001) and 0.43 in the Malays (p < 0.001). The frequencies of haplotype S+, L+ and L- were, respectively, 0.37, 0.40 and 0.23 in the Chinese, 0.65, 0.18 and 0.16 in the Dravidian Indians and 0.54, 0.37 and 0.09 in the Malays.(ABSTRACT TRUNCATED AT 250 WORDS)

Population genetic study among the Orange Asli (Semai Senoi) of Malaysia: Malayan aborigines

A population genetic study was undertaken to provide gene frequency data on the additional blood genetic markers in the Semai and to estimate the genetic relations between the Semai and their neighboring and linguistically related populations by genetic distance and principal components analyses. Altogether 10 polymorphic and 7 monomorphic blood genetic markers (plasma proteins and red cell enzymes) were studied in a group of 349 Senoi Semai from 11 aboriginal settlements (villages) in the Pahang State of western Malaysia. Both the red cell glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (PGD) loci reveal the presence of polymorphic frequencies of a nondeficient slow allele at the G6PD locus and a fast allele at the PGD locus. The Semai are characterized by high prevalences of ahaptoglobinemia and G6PD deficiency, high frequencies of HP*1, HB*E, RH*R1, ACP*C, GLO1*1, PGM1*2+, and GC*1F and corresponding low frequencies of ABO*A, HbCoSp, HB*B0, TF*D, CHI, and GC*2. Genetic distance analyses by both cluster and principal components models were performed between the Semai and 14 other populations (Malay; Javanese; Khmer; Veddah; Tamils of Malaysia, Sri Lanka, and India; Sinhalese; Oraon; Toda and Irula of India; Chinese; Japanese; Koreans) on the basis of 30 alleles at 7 polymorphic loci. A more detailed analysis using 53 alleles at 13 polymorphic loci with 10 populations was carried out. Both analyses give genetic evidence of a close relationship between the Semai and the Khmer of Cambodia. Furthermore, the Semai are more closely related to the Javanese than to their close neighbors--the Malay, Chinese, and Tamil Indians. There is no evidence for close genetic relationship between the Semai and the Veddah or other Indian tribes. The evidence fits well with the linguistic relationship of the Semai with the Mon-Khmer branch of the Austro-Asiatic language family.

Inflammatory response in bacterial meningitis: cytokine levels in the cerebrospinal fluid

Inflammatory response plays an important role in the pathogenesis of cerebral injury in bacterial meningitis. In this study, we evaluated the cytokine levels of interleukin 1-beta (IL1 beta), tumour necrosis factor alpha (TNF alpha) and interleukin 6 (IL6) in the cerebrospinal fluid (CSF), and determined their correlation with acute clinical complications and with changes in CSF biochemistry. Interleukin 6, TNF alpha and IL1 beta were present in 9/9, 3/9 and 4/9 patients, respectively. The CSFs with detectable TNF alpha or IL1 beta had higher levels of IL6 (p < 0.02), protein (NS) and lower glucose levels (p < 0.02), compared with those in which TNF alpha and IL1 beta were absent. Tumour necrosis factor alpha and IL1 beta levels also correlated with the presence of prolonged fever, fits, spasticity and death (logTNF alpha: r = 0.70, p < 0.05; logIL1 beta: r = 0.62, p = 0.08). The cytokine levels reflect the degree of inflammatory response and are positively correlated with the severity of acute clinical complications. Modulation of this inflammatory response in bacterial meningitis may improve its morbidity and mortality.

Association of factor VII genotype with plasma factor VII activity and antigen levels in healthy Indian adults and interaction with triglycerides

Plasma factor VII activity (factor VIIc) is one of the independent risk factors for coronary artery disease and is controlled by both genetic and environmental factors. Several studies in healthy Caucasian subjects have revealed an association of a common genetic polymorphism at residue 353 (Arg-->Gln) of the factor VII gene with plasma factor VIIc. We have investigated the influence of this polymorphism (factor VII Arg/Gln353) on fasting plasma factor VIIc and antigen (factor VIIag) levels and its interaction with triglyceride levels in 185 healthy Dravidian Indians of both sexes (128 men, 57 women). The frequency of Gln353 has been found to be significantly higher in Dravidian Indians (0.29; confidence interval, 0.27 to 0.30) than in Caucasians (0.10). The distribution of factor VII Arg/Gln353 genotypes was at Hardy-Weinberg equilibrium. The carriers of the Gln353 allele had significantly lower plasma factor VIIc and factor VIIag in men (P < .05). The factor VII Arg/Gln353 polymorphism explained 13% and 11% of the total variance of plasma factor VIIc and factor VIIag, respectively, in men (P < .001) and 6% and 9% in women (P > .1). The genotype-specific correlation of factor VIIc and factor VIIag with triglyceride levels was stronger in carriers of the Gln353 allele (r = .38 and .41; P < .001) than in Arg353 homozygotes (r = .09 and .27; P = .19 and .005, respectively).

Molecular characterisation of red cell glucose-6-phosphate dehydrogenase deficiency in Singapore Chinese

Sixty-two G6PD deficient Chinese males have been investigated for the presence of seven mutations of the coding region of the G6PD gene by natural and artificially created amplified restriction sites. The results show that the G to T substitution at nucleotide (nt) 1376 and G to A substitution at nt 1388 represent 24% and 21% of G6PD deficiency, respectively, in the Singapore Chinese; 37% of the sample could not be characterised. The remaining samples were identified as follows: 10% C-->T at nt 563, 5% A-->G at nt 95, and 3% C-->T at nt 1024. The G to A substitution (nt 487) and the substitution A-->G (nt 493) were not present in this sample. None of the subjects with the Mediterranean mutation (563 C-->T) had the silent mutation at 1311 (C-->T). This study confirms the extreme molecular heterogeneity of the G6PD gene in the Chinese.

The amplification refractory mutation system (ARMS): a rapid and direct prenatal diagnostic technique for beta-thalassaemia in Singapore

beta-Thalassaemia major patients have chronic anaemia and since 3-4 per cent of Singaporeans carry the beta-gene, prenatal diagnosis is essential. We evaluated the amplification refractory mutation system (ARMS) technique as a routine test for prenatal diagnosis of beta-major. Six mutations along the beta-gene were studied--41-42 (-TCTT), IVSII #654 (C-T), 17 beta (A-T), -28 TATA (A-G), IVSI #5 (G-C), and IVSI #1 (G-T). Our results indicate that prenatal diagnosis using these mutations can be offered to 90 per cent (35/39) of our Chinese couples and 54.6 per cent (12/22) of our Malay couples at risk. Confirmation of ARMS results was carried out using allele-specific oligonucleotide hybridization. Prenatal diagnosis using ARMS was successfully carried out in nine cases which included a set of triplets and twins. The triplets were diagnosed with the beta-trait carrying the 41-42 mutation. The couple with twins possessed the #654 mutation and one twin was diagnosed with the beta-trait and the other with #654 homozygosity. Genomic sequencing of the undefined mutations in the Chinese couples revealed rarer mutations at -29 and an ATG-AGG base substitution at the initiation codon for translation. In the Malay couples, genomic sequencing detected mutations at codon 15 (TGG-TAG) and codon 26 (GAG-AAG). We conclude that ARMS with its direct detection of amplified products by gel electrophoresis provides an accurate, rapid, and simpler method for our beta-thalassaemia prenatal diagnosis programme in Singapore.

Distribution of plasma alpha-1-B-glycoprotein (A1BG) polymorphism in several populations of the Indian subcontinent

The distribution of plasma alpha 1B-glycoprotein (A1BG) was determined by a two-dimensional electrophoresis (agarose-polyacrylamide gel) followed by protein staining in a group of 1099 individuals from 11 populations of the Indian subcontinent. The sample comprised 454 from several tribes of Arunachal Pradesh; 76 Bengali Hundus and 88 Bengali Muslims; 179 Tamil Hindus from Singapore and 107 from India; 81 Tamil Muslims, 48 Sinhalese from Sri Lanka and 66 North Indians. Three common A1BG phenotypes (1-1, 1-2 and 2-2) were observed in this study. One each of a new allele (A1BG*7) in heterozygous form (1-7) was detected respectively among Tamil Hindus of India and Singapore. The phenotypic distribution of A1BG alleles was at Hardy-Weinberg equilibrium in all the populations. The frequency of A1BG*2 was in general lower in the Mongoloid tribes of Arunachal Pradesh (0.043-0.104) and North Indians (0.068) compared to that in other Indian populations (0.130-0.171) and Sinhalese (0.208).

The diagnosis of tuberculous meningitis using the polymerase chain reaction

AIM

DNA amplification by the polymerase chain reaction (PCR) was evaluated as a means for rapid diagnosis of tuberculous meningitis (TBM).

METHODS

A 240 bp region (nts 460-700) from the MPB 64 protein coding gene specific for Mycobacterium tuberculosis (TB) was selected for amplification. Nineteen clinical samples were studied. Six were obtained from patients with TBM diagnosed by culture (4/6) or by response to therapy (2/6). The remaining 13 samples were obtained from patients with febrile seizu es (8/13), aseptic meningitis (3/13) and septic meningitis (2/13), and these served as negative controls.

RESULTS

We detected TB DNA in all the 6 CSF specimens obtained from patients with TBM. PCR alone was sufficient to detect TB DNA in 5 of these 6 samples. However, one sample was positive only when PCR was followed by oligonucleotide hybridisation. In the 2 patients whose CSF were obtained only after commencement of TB therapy, TB cultures were negative but positive on PCR nd oligoprobe labelling. The diagnosis of TBM was confirmed based on their remarkable response to therapy. Twelve of the thirteen negative controls were TB DNA negative. There was one false positive sample, which was thought to be due to TB DNA contamination.

CONCLUSION

Taken together, our results indicate that DNA amplification using PCR, followed by oligonucleotide hybridisation offers a rapid (5 working days) means of diagnosis of TBM, provided care is taken to ensure that cross contamination of DNA samples is avoided.

Effect of apolipoprotein E variants on plasma lipids and apolipoproteins in the Orang Asli ('aborigines') of Malaysia

Members of the Semai group of Orang Asli ('aborigines') in peninsular Malaysia were examined for apolipoprotein E (apo E) variants in relation to plasma total cholesterol (TC), high density lipoprotein cholesterol, low density lipoprotein cholesterol (LDLC), triglycerides (TG), apolipoprotein AI and apolipoprotein B (apo B). The e2 and e4 alleles were found to be higher than in most other groups as reported. The sample as a whole was normotriglyceridaemic (mean plasma TG, 1.5 mmol/l) and very markedly hypocholesterolaemic (mean plasma TC 1.7 mmol/l). The distribution of apo E variants was not related to any of the plasma lipids or apolipoprotein fractions using results from all subjects, but if a distinctly hypertriglyceridaemic sub-section was omitted (TG > 1.7 mmol/l) then apo E variants were determinants of plasma TC, LDLC, and apo B concentrations, the lower values of these being associated with the 2-2 and 2-3 genotypes, and the higher with 3-4, and 4-4.

DNA amplification by the polymerase chain reaction for the rapid diagnosis of tuberculous meningitis. Comparison of protocols involving three mycobacterial DNA sequences, IS6110, 65 kDa antigen, and MPB64

DNA amplification of three Mycobacterium tuberculosis-specific DNA sequences by the polymerase chain reaction (PCR) were evaluated as a means for rapid diagnosis of tuberculous meningitis (TBM). The DNA sequences amplified were a 123 bp region of the IS6110 insertion elements which occur in multiple copies in the mycobacterial genome, a 240 bp region (nts 460-700) from the MPB 64 protein coding gene, and the 383 bp region of the 65 kDa heat shock protein (HSP) antigen. Twenty-seven cerebrospinal fluid (CSF) specimens were studied. Six were obtained from patients with TBM diagnosed by culture (4/6) or by the patients' response to anti-tuberculous therapy (2/6). The remaining 21 specimens were obtained from patients with febrile seizures (3/21), aseptic meningitis (3/21), septic meningitis (14/21), and cryptococcal meningitis (1/21), and these served as negative controls. Our results indicate that although the protocols involving the 3 DNA sequences were able to detect TB DNA in the 6 TBM specimens, the main drawback was their extreme sensitivity, thus giving rise to false positive results. In particular, the repeat copy sequence, IS6110, and the 65 kDa HSP gave unacceptably large numbers of false positive results (62% and 33%, respectively).

Molecular characterisation of red cell glucose-6-phosphate dehydrogenase deficiency in north-west Pakistan

233 Pushtoons (129 males and 104 females), 51 Punjabi Muslims (29 males and 22 females) and 21 Afghans (15 males and 6 females) were screened for the presence of red cell glucose-6-phosphate dehydrogenase (G6PD) variants by a dye decolouration screening test and starch gel electrophoresis. The overall frequency of G6PD deficiency in males was found to be about 10%. 17 male G6PD-deficient samples were further investigated for the C-->T substitution at nucleotide (nt) 563 (the Mediterranean mutation) and the C-->T substitution at nt 1311 (the 'silent' allele) of the G6PD gene by PCR amplification followed by digestion with appropriate restriction enzymes. 10 of the 13 Pushtoon, 2 Punjabi and 1 Afghan males had the 563 mutations. Only 1 (Punjabi) out of 13 G6PD-deficient males with the 563 mutation had the silent mutation at nt 1311. The frequency of the silent mutation was found to be about 0.20 in the 60 Pushtoon and 19 Punjabi non-deficient males.

Influence of polymorphisms for apolipoprotein B (ins/del, XbaI, EcoRI) and apolipoprotein E on serum lipids and apolipoproteins in a Javanese population

A total of 231 healthy subjects from a central Javanese population were investigated for the distribution of three apolipoprotein B (apo B) polymorphisms (ins/del, XbaI, and EcoRI), as well as apolipoprotein E (apo E) polymorphism in relation to serum lipid and apolipoprotein concentrations. The frequencies of the rarer alleles (del, 0.09; X+, 0.1; and R-, 0.06) were lower than have been found for some Asian and European populations. Distribution of genotypes was in Hardy-Weinburg equilibrium for all the polymorphisms. A linkage disequilibrium was observed only between the ins/del and XbaI site polymorphisms of apo B (chi 2(4)) = 25.3; P < 0.001) consistent with that observed in some other population studies. No polymorphism of the apo B gene had an association with serum lipid or apolipoprotein concentrations in this population except for XbaI, which appeared to be associated with serum TG (as the log transform: R2 = 8.3; F = 4.8; P < 0.01). The apo E4 allele was found to be associated with significantly higher serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC). Apo E polymorphism explained 5.9% of the sample variance of serum LDLC (F = 5.4; P < 0.01).

Lack of association of the dopamine D3 receptor gene polymorphism (BalI) in Chinese schizophrenic males

Dopamine receptors have been implicated in the aetiology of schizophrenia and mode of action of antipsychotic drugs. A finding of increased homozygosity at the D3 receptor gene (BalI locus) has recently been reported. We have investigated the distribution of D3 receptor gene polymorphism (BalI) in 137 schizophrenic Chinese males and 125 healthy matched controls. The frequency of the rare allele was 0.30 and 0.31 in the patient and the control series. The distribution of genotypes in the patient series did not deviate significantly from Hardy-Weinberg equilibrium in the present series.

Guanidine to adenine (G/A) substitution in the promoter region of the apolipoprotein AI gene is associated with elevated serum apolipoprotein AI levels in Chinese non-smokers

The influence of the guanidine to adenine (G/A) substitution in the promoter region of the apolipoprotein (apo) AI gene (at -75 bp) on serum lipids and apolipoproteins was studied in 287 healthy Chinese of both sexes in Singapore. Women had significantly higher levels of high-density lipoprotein cholesterol (HDLC) and apo AI and lower low-density lipoprotein cholesterol (LDLC). The distribution of genotypes was at Hardy-Weinberg equilibrium. The frequency of the A allele in the Chinese was significantly higher [0.27; 95% confidence interval (CI) 0.24-0.31] than that reported in Caucasians (0.12; 95% CI 0.09-0.14). In men, the A allele was associated with 20% higher apo AI; this association was completely absent in women. Furthermore, in men this association was only observed in those who had never smoked, and was absent in smokers. The G/A substitution explained 9% (P < 0.02) of the sample variance of apo AI in non-smoking men. The modulating influence of smoking could not be examined in women because too few women smoke. Although the impact of this polymorphism is modulated by hormones and smoking, it is of importance in determining levels of apo AI in healthy Chinese individuals. No association of the G/A substitution of the apo AI gene was observed with any other lipid traits.

Interrelationships of serum paraoxonase, serum lipids and apolipoproteins in normal pregnancy. A longitudinal study

Serum paraoxonase (EC 3.1.1.2) may be implicated in the lipid metabolism. In order to substantiate this view we conducted a longitudinal study of interrelationships of serum paraxonase, lipids and apolipoproteins during pregnancy. Fasting serum levels of paraoxonase, serum lipids (total, HDL and LDL cholesterols, triglycerides) and apolipoproteins (AI, AII and B) were estimated in 91 pregnant women at 28 and 32 weeks of gestation and 6 weeks after delivery, and 40 nonpregnant women. Serum paraoxonase, total HDL and LDL cholesterol levels were significantly higher during pregnancy along with corresponding apolipoprotein (p < 0.001). The most striking increase was seen in serum triglycerides and paraoxonase levels (p < 0.001). Serum paraoxonase levels had a significant correlation with triglycerides (r: 0.45-0.60) and Apo-AII (r: 0.32-0.41) in both pregnant and nonpregnant states (p < 0.001). Moreover, both serum paraoxonase and triglyceride levels at 28 weeks of pregnancy were negatively correlated with birth weight (r: 0.3, p < 0.05), suggesting a possible role of paraoxonase in energy delivery for fetal development derived from maternal hypertriglyceridemia.

Molecular characterization of beta-thalassaemia in Singaporean Chinese: application to prenatal diagnosis

Sixty-five beta-thalassaemia genes from 14 unrelated Chinese beta-thalassaemia major patients and 37 Chinese beta-carriers were analysed by allele-specific oligonucleotide (ASO) hybridization after DNA amplification by the polymerase chain reaction (PCR). Six mutations were studied and are represented by 49.2% of codon 41-42, 30.8% of IVSII #654, 6.2% of 17 beta, 3.1% of IVSI #5 (G-->C) and 1.5% of -28 TATA box. The complete mutations responsible for beta-thalassaemia major in 13 of our 14 affected families were identified. For these families prenatal diagnosis at 10 weeks gestation using DNA amplification and ASO hybridization will replace the globin chain biosynthesis technique at 19 weeks gestation. Using ASO analysis, our results indicate that 5 oligo-probes (41-42, II-#654, 17 beta, IVSI-#5 and -28) allow determination of beta-thalassaemia mutations in 59/65 (90.8%) of the Singaporean Chinese studied.

DNA polymorphisms of the apolipoprotein B gene are associated with obesity and serum lipids in healthy Indians in Singapore

Three DNA polymorphisms (Ins/Del, XbaI and EcoRI) of the apolipoprotein B gene and their influence on body-mass index, serum lipids and apolipoprotein levels were studied in 181 healthy Indians of both sexes (121 males and 60 females), aged between 17 and 71 years. The frequencies of X+ (XbaI) and Del (Ins/Del) of the signal peptide region in Indians were found to be significantly lower (0.17 and 0.11, respectively) compared to the frequencies in Caucasians (0.50 and 0.32, respectively) (P < 0.025). The frequency of E- (EcoRI) was similar to that in Caucasians (0.10 vs 0.15). A highly significant linkage disequilibrium was observed between the XbaI site and Ins/Del polymorphism of the apo B gene in this sample (X2 = 31.9, P < 0.001). The simultaneous presence of Del and X+ allele was significantly associated with higher body mass index (X2 = 11.43, P < 0.005), serum total cholesterol (X2 = 5.11; P < 0.025) and triglyceride (X2 = 6.42; P < 0.025) levels. Mean values of adjusted BMI and serum triglyceride levels were found to be 29.0 +/- 1.92 vs 23.7 +/- 0.67 (P < 0.025) and 278.0 +/- 60.78 vs 140.4 +/- 15.43 mg/dl (P < 0.05), respectively, in subjects with Del and X+ compared to others. The multiple regression tests showed that 3.3 and 5.8% of the total variability of BMI is explained by Ins/Del and XbaI polymorphism, respectively, in this sample (P = 0.06 and 0.02), while 3.8% of serum triglyceride levels was explained by Ins/Del polymorphism of the apo B gene (P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

DNA polymorphisms of the apolipoprotein B gene in Chinese coronary artery disease patients

Five restriction fragment length polymorphisms (RFLP) of the apo B gene and their association with serum lipids and apolipoprotein levels have been studied in 139 Chinese patients with angiographically confirmed CAD (mean age 56.2 +/- 0.8 years) and 154 healthy Chinese subjects (mean 44.0 +/- 1.0 years) of both sexes. The patient group had significantly higher levels of serum total and LDL cholesterol; and apo B (P < 0.001) and lower HDL cholesterol and apo A-I (P < 0.001 and < 0.01, respectively). The frequencies of the rarer alleles of the ins/del, XbaI and EcoRI (but not the PvuII and MspI) polymorphisms were significantly lower in the Chinese compared to those reported in Caucasians. There was no significant difference in allelic frequencies of the signal peptide region (Ins/Del), XbaI, MspI and EcoRI sites of the apo B gene between the patient and control groups. The frequency of the rarer allele of the PvuII RFLP was significantly lower in the CAD patients (P < 0.05) compared to that in the control group (0.05 vs 0.10). None of the DNA polymorphisms was associated with a significant influence on serum lipid and apolipoprotein levels in the patients with coronary artery disease.

Deletion analysis of DMD/BMD children in Singapore using multiplex polymerase chain reaction (PCR) technique

Twenty-three children suffering from Duchenne/Becker muscular dystrophy (DMD/BMD) in Singapore were analysed using the multiplex polymerase chain reaction (PCR) technique. Deletions were found in 14 cases. One rare case of total deletion of all nine exons was observed. This is the first DMD/BMD deletion analysis on South East Asian children. This technique for screening deletions was informative in 61 per cent of the local cases and would be useful for rapid diagnosis of deletion cases of DMD/BMD.

Pathogenesis of Duchenne muscular dystrophy: the calcium hypothesis revisited

Rapid advances in the molecular genetics of Duchenne muscular dystrophy (DMD) and the discovery and localization of the gene product dystrophin has brought new hope that successful treatment for this disease may not be too far away. Dystrophin has been postulated to have a mechanical function, helping to resist stress associated with muscle contraction. The presence of dystrophin in low concentrations in muscle cells, its expression in nervous tissue and the observation that hypercontraction of the sarcomeres precedes membrane rupture make the hypothesis unlikely. On the basis of an analogy with a cytoskeletal protein ankyrin, which is associated with the sodium/potassium adenosine triphosphatase (ATPase) in the kidney, it is possible that dystrophin deficiency leads initially to an increased but inefficient calcium-ATPase activity, which pumps calcium out of the cell. Partial failure of the pump would result in intracellular accumulation of calcium, hypercontractions of the sarcomeres, rupture of the cell membrane, massive influx of calcium and cell necrosis.

Association of haptoglobin types with serum lipids and apolipoproteins in a Chinese population

Association of haptoglobin types with serum lipids and apolipoprotein levels was investigated in a healthy Chinese population of both sexes (n = 679) in Singapore. The frequency of Hp1 and Hp2 was found to be 0.30 and 0.70, respectively. The distribution of haptoglobin phenotypes was at Hardy-Weinberg equilibrium in this population. There was an excess of Hp2 in individuals with the upper two quartiles of serum total cholesterol levels compared to those with the lower two quartiles in both sexes (X1(2): 11.84; P less than 0.001). Subjects with Hp 2-2 had significantly higher serum total and LDL cholesterol levels (243.8 +/- 2.83 and 165.9 +/- 2.48 mg/dl) compared to those in other haptoglobin types (230.7 +/- 2.58 and 154.9 +/- 2.49 mg/dl), respectively (P less than 0.001 and 0.002) after adjustments for age, sex and BMI. No other lipid (HDL cholesterol and triglyceride) and apolipoprotein (apo A-I, A-II and B) traits were associated with haptoglobin types. ANOVA statistics using age, sex and BMI as covariates showed that 1.8% of total variability of serum total cholesterol and 2.1% of serum LDL cholesterol could be explained by haptoglobin types (P 0.008 and 0.003, respectively). It is concluded that haptoglobin polymorphism is significantly associated with serum total and LDL cholesterol levels in this Chinese population.

Apolipoprotein H (beta-2-glycoprotein I) polymorphism in Asians

Apolipoprotein H (APOH) (beta-2-glycoprotein I) polymorphism has been studied in 1159 Asians. The sample included 872 Chinese, 179 Asiatic Indians (Dravidian), 91 Filipinos, and 17 Malays. APOH polymorphism was determined by isoelectric focusing of sera in thin-layer polyacrylamide gels containing 3 M urea followed by immunoblotting. The frequencies of the three alleles--APOH*1, APOH*2, and APOH*3--were found to be 0.031, 0.900, and 0.069 in the Chinese; 0.061, 0.866, and 0.073 in the Dravidian Indians; 0.055, 0.923, and 0.022 in the Filipinos; and 0.088, 0.882, and 0.029 in the Malays. The phenotypic distribution was at Hardy-Weinberg equilibrium in all the populations.

Population genetics of coagulation factor XIIIB in three ethnic groups of Singapore

The distribution of plasma coagulation factor XXIIB polymorphism was determined by PAG isoelectric focusing and immunoblotting in a group of 670 subjects comprising 375 Chinese, 110 Malays and 185 Indians. The frequencies of FXIIIB*1, FXIIIB*2, and FXIIIB*3 were found to be 0.27, 0.03 and 0.70 in the Chinese; 0.33, 0.05 and 0.64 in the Malays and 0.58, 0.08 and 0.33 in the Indians. The phenotypic distribution of FXIIIB alleles was at Hardy-Weinberg equilibrium in all three populations. A two-dimensional principal-components analysis on the basis of three common alleles at the FXIIIB locus among 19 populations, so far studied, clearly differentiates the Negroid, Mongoloid and Caucasoid populations into three major groups with the exception of Amerindians (Minnesota) and US Blacks showing some Caucasoid influence.