G Wessels

Stellenbosch University, Stellenbosch, Province of the Western Cape, South Africa

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Publications (53)69.61 Total impact

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    ABSTRACT: Fine-needle aspiration biopsy (FNAB) has been widely accepted as a reliable diagnostic modality in the general pediatric population, but its role in pediatric oncology still remains elusive. With new treatment protocols subscribing to preoperative chemotherapy, the need for a quick, minimally invasive, and accurate diagnostic procedure has arisen. This study assesses the feasibility of FNAB in childhood malignancies to render a specific diagnosis on which treatment can be initiated. An 11-year retrospective study was done on FNABs in patients 19 years and under referred for clinically malignant mass lesions. Cases were confirmed with histology, immunocytochemistry, flow cytometry, or clinical follow-up. Of the 357 patients referred for FNABs, 36 patients were lost to follow-up and 31 FNABS were inadequate. A total of 290 cases were included in the study, of which 68 (23%) cases were benign and 222 (77%) were malignant. The most frequently occurring tumors were nephroblastoma (68), non-Hodgkin's lymphoma (39), rhabdomyosarcoma (22), Hodgkin's lymphoma (22), and neuroblastoma (22). The sensitivity of the procedure for neoplasia was 96.6%, the specificity 97.0%, positive predictive value 99.0%, and negative predictive value 90.1%, with a diagnostic accuracy of 96.7%. The ability of FNAB to enable a specific diagnosis to be made, that is correct and accurate subtyping of the tumor on which chemotherapy or radiotherapy could be commenced was 75.7%. This study shows that FNAB can be used with confidence to confirm malignancy in children. With clinicoradiological correlation and the aid of ancillary techniques, FNAB allows a rapid and accurate preoperative diagnosis for definitive therapy commencement in most cases.
    Full-text · Article · Sep 2012 · Diagnostic Cytopathology
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    ABSTRACT: BACKGROUND IN ADULTS,: HIV increases the risk of certain cancers known, or thought, to have an underlying infectious etiology; the impact on the risk of cancer in children is less clear. Here, we report results of an on-going study at four pediatric oncology centers in South Africa in which children diagnosed with cancer are tested routinely for HIV. Odds ratios (OR) for the prevalence of various malignancies were calculated (with adjustment for age, sex, and center) for the children infected with HIV using all children with cancer and non-malignant conditions, but not infected with HIV, as a comparison group. Of 882 children with cancer, 38 were HIV infected (for 12 the HIV status was unknown). HIV was associated with Kaposi sarcoma (all 10 cases were HIV infected; P < 0.001) and with Burkitt lymphoma (OR = 46.2, 95% confidence interval (CI) 16.4-130.3; 13/33). For non-Burkitt non-Hodgkin lymphoma (NHL), 2/39 were HIV infected (OR = 5.0, 95% CI 0.9-27.0). No other cancer type was significantly associated with HIV, including lymphoid leukemias (OR = 0.4, 95% CI 0.04-2.9; 1/172). Only Kaposi sarcoma and Burkitt lymphoma were significantly associated with HIV infection although results for non-Burkitt NHL were suggestive. Notably, we did not identify an association between infection with HIV and lymphoid leukemias, for which an underlying infectious etiology has been suggested.
    No preview · Article · Jan 2011 · Pediatric Blood & Cancer
  • Pb Hesseling · G Wessels · Aj Van Buuren · S Mouton

    No preview · Article · Jul 2009 · Pediatric Hematology and Oncology

  • No preview · Article · Jul 2008
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    ABSTRACT: Malignant liver tumors (mostly hepatoblastoma [HB] and hepatocellular carcinoma [HCC]) are uncommon, representing 0.5%-2% of childhood malignancies worldwide. The pattern of liver tumors appears to differ in Southern Africa as a result of infectious factors (e.g., hepatitis B/retroviral disease (HIV). This study aimed to assess recent changes in the prevalence and surgical management of liver tumors in South African children. Data were obtained from the tumor registry and pediatric oncology units in South African hospitals to audit and review the epidemiology, treatment, and outcome of malignant hepatic tumors in South African children. Malignant primary hepatic tumors were reported in 274 children (ages 0-14 years) from 1988 through June 2006. Of these 134 (48%) had HB; 77 (27%) had HCC (9 [3%] fibrolamellar subtype); 38 (13%), vascular tumors; and 17 (6%), liver sarcomas. In a further 8 patients (3%) other tumors included lymphoma and endodermal sinus tumor. Vascular tumors included hemangioendotheliomas (12), and there were 5 malignant tumors in children with HIV, including 1 angiosarcoma and 13 Kaposi sarcoma-like tumors. Hepatoblastoma occurred at a mean age of 1.47 years, and none were encountered in patients > 4 years of age. Hepatocellular carcinoma mostly occurred in the older patients (mean age: 10.48 years), but 6% presented in patients < 8 years of age (10 months, 2, 2.6, 5, 5, and 6 years). Hepatic sarcoma occurred at a mean age of 7.66 years and had a female predominance (M:F ratio: 0.4). The relative HCC prevalence (male predominant: hepatitis B related) was reflected in the low HB:HCC (1.67) ratio. However, a significant decrease in HCC was attributed to the effect of hepatitis B inoculation. There appeared to be an increase in the incidence of vascular tumors, presumably the result of an increase in Kaposi-like sarcoma in retrovirus-positive patients. The surgical resection rate was low because most patients presented late, with advanced disease. Survival was 11% and 52% for HB and HCC, respectively, and was related to chemotherapeutic response and complete surgical resection. Liver tumors appear to have a different epidemiological pattern in South Africa. The observed increased HCC prevalence appears to be decreasing with hepatitis B vaccination. Retroviral disease does not yet appear to have a major influence on the distribution of liver tumors in South Africa, although it possibly affects the vascular tumor prevalence.
    No preview · Article · Jul 2008 · World Journal of Surgery
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    ABSTRACT: Chemotherapy for cancer can cause immunocompromise. The authors speculated that children with cancer and low vitamin A plasma levels were more susceptible to cancer treatment-related complications than children who are not vitamin A deficient. A cohort of 49 children with cancer were followed from diagnosis until death or for at least 5 years. Plasma retinol levels were determined at diagnosis. Complications of treatment were recorded. Children with low retinol levels at diagnosis tended to have more chance to develop febrile neutropenia (p = .052). Children with fever had lower mean vitamin A levels at diagnosis than those who did not suffer febrile episodes. In a childhood population with a high prevalence of vitamin A deficiency, routine vitamin A assessment and supplementation in children with cancer appears indicated.
    No preview · Article · Jul 2008 · Pediatric Hematology and Oncology
  • D C Stefan · AL Kruis · H S Schaaf · G Wessels
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    ABSTRACT: There is a dearth of studies addressing the incidence and clinical presentation of tuberculosis (TB) in children with cancer. To evaluate the incidence of TB in paediatric oncology patients at Tygerberg Hospital, located in a Cape Town area of high TB prevalence, and to describe the clinical characteristics of the disease in this particular group of patients whose treatment typically suppresses their immune response. We reviewed the records of 625 paediatric oncology patients admitted from 1 January 1991 to 31 December 2005. Of these, 87 received treatment for TB; however, only 57 cases had sufficient data to support a diagnosis of TB and only these were used for further analysis. In the children with TB, acute lymphoblastic leukaemia (ALL) was the most common malignancy (13/57, 22.8%). The incidence of TB in the study group was 9117/100,000/year, which is 22 times higher than the overall TB incidence reported in children from a similar background. Importantly, 47% of the active infections appeared in the 1st 5 months of chemotherapy, suggesting reactivation of latent TB. Identifying latent TB in our patients and providing prophylactic treatment during the initial months of chemotherapy might have prevented disease progression in these cases. Routine screening of paediatric oncology patients for latent TB infection and exclusion of active disease prior to initiation of cancer therapy might be indicated in TB-endemic areas.
    No preview · Article · Jul 2008 · Annals of Tropical Paediatrics International Child Health

  • No preview · Article · Jan 2008 · South African journal of child health
  • D.C. Stefan · G. Wessels
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    ABSTRACT: Introduction. Idiopathic thrombocytopenic purpura (ITP) is the most common bleeding disorder of childhood Aim. To describe the management of ITP in South Africa. Methods. A survey was sent to 410 doctors in the country, describing four different scenarios in children newly diagnosed with ITP and soliciting responses concerning the diagnosis and management. Results. Steroids were the first line of choice in treating ITP. Anti-D immunoglobulin was not considered in the management, and the most practitioners would perform a bone marrow aspiration even if no treatment with steroids would be given. The vast majority of the patients would be treated in hospital. Conclusions. This is the first study done in South Africa (and in Africa), and it shows a great variation in the management of children with newly diagnosed ITP. Prospective studies in developing countries where various constraints to health care delivery exist are required to produce evidence-based recommendations for this patient group.
    No preview · Article · Jan 2008
  • D C Stefan · R Uys · G Wessels
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    ABSTRACT: A 23-month-old girl presented with heart failure from extremely severe sickle cell anemia. The family refused blood transfusion on religious grounds (Jehovah's Witness). Alternative options acceptable to this religion, such as iron, erythropoietin, or folic acid were rejected as useless in the particular situation of the child. The patient was transfused with Hemopure, a product that consists of polymerized bovine hemoglobin. This is the first case reported in the literature of a child transfused, in an emergency situation, with this product.
    No preview · Article · Jul 2007 · Pediatric Hematology and Oncology
  • A Dippenaar · G Wessels · P B Hesseling
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    ABSTRACT: A historical cohort study with an analytical component was conducted to determine whether risk-appropriate chemotherapy can improve survival in children of mixed ethnicity with ALL. Eighty-one coloured children treated for ALL in South Africa were divided into 2 groups: group A (n = 39), treated prior to 1992, and group B (n = 42), treated after 1992. A comparison was made of survival, treatment complications, and supportive measures. The two groups were comparable. The mean nadirs of the white cell count (p < .01), platelet count (p = .01), and hemoglobin value (p < .01) were significantly lower in group B. The survival rate of 37% in group A improved to 66% in group B (p = .025). The results show that a risk-adapted regimen increased survival in children of mixed ethnicity in the Western Cape, despite increased hematological toxicity and episodes of febrile neutropenia.
    No preview · Article · Jul 2006 · Pediatric Hematology and Oncology
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    ABSTRACT: [No abstract available] Letter
    Full-text · Article · Nov 2005 · South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde
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    ABSTRACT: We previously reported 57% 12-month event free survival (EFS) in Malawian children with stage I to III Burkitt lymphoma (BL) with an intermediate dose chemotherapy protocol lasting 77 days. This protocol was shortened to 42 days and evaluated in children with stage I to IV disease for EFS and toxicity. All Malawian children admitted to Queen Elizabeth Central Hospital, from 03/08/2000 to 12/03/2002 with confirmed BL were eligible. A fine needle aspirate, bone marrow aspirate, cerebrospinal fluid cytology, haemoglobin (Hb), white cell count (WCC), malaria smear, ELISA for HIV, and abdominal ultrasound were performed routinely. Murphy staging was used. The first dose of chemotherapy (COP1) consisted of 300 mg cyclophosphamide (CPM), 1 mg vincristine, and 60 mg prednisone given on day 1 and followed by COP2 on day 8 (only for patients with larger tumour volumes, stage III or IV disease). The vincristine dose in COP2 was 2 mg. COMP1 and 2 given on days 22 and 36 consisted of 500 mg CPM, 2 mg vincristine, 60 mg prednisone, and 2 g methotrexate. All doses were calculated per body surface area. Intrathecal methotrexate and hydrocortisone were given with COP1 and 2. Forty-two patients, 30 boys and 12 girls median ages 6 and 7.5 years, respectively, had Murphy stage I(n5), II(n8), III(n21), and IV(n8) disease. The face was involved in 74%, abdomen in 55%, bone marrow in 14%, kidneys in 24%, and 12% had paraplegia. Fourteen children died during or shortly after completion of chemotherapy. Three of these were disease related. Twelve patients suffered a local relapse after 57-328 days, and one a CNS relapse at 76 days. The projected EFS at 12 months is 50% in stage I, 50% in stage II, 24% in stage III, 25% in stage IV, and 33% for all patients. The cumulative mean dose of CPM was 62 mg/kg in survivors and 64 mg/kg in children who relapsed. One third of patients experienced significant marrow suppression, and infections after COMP1. Thirty-three percent of children are in first remission at 12 months. The morbidity and mortality of treatment was high. The high relapse rate in all stages may be due to the low cumulative dose of CPM.
    No preview · Article · Mar 2005 · Pediatric Blood & Cancer
  • Glynn Wessels · Peter Bernard Hesseling
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    ABSTRACT: Hodgkin's disease (HD) in children corresponds to a large degree to HD in adults. Non-Hodgkin's Lymphoma (NHL) in children, however, differs from NHL in adults with respect to the classification, natural history, management and course. For practical reasons clinicians generally classify and treat NHL in children as either B-cell or T-cell disease. Over the past 22 years, the Paediatric Oncology Unit of the Tygerberg Hospital has treated HD with three different regimens. Use of the CLVPP and MOPP/ABVD regimens resulted in late relapses that adversely affected event free survival (EFS). For the last four years HD has been treated according to the regimen suggested by Schellong with good short term survival rates. Lymphoblastic or T-cell NHL is treated with regimens normally used for acute lymphoblastic leukaemia (e.g. BFM protocols) or modified leukaemia treatments for leukaemia-lymphoma syndromes (e.g. LSA2L2). We lately use a modified BFM regimen with a 70% EFS for all stages. Three consecutive regimens have been used to treat B-cell NHL over the past 22 years. The first was a COMP regimen, followed by the LMB-89 and LMB-96 regimens. Although toxicity has increased with the increased intensity of the treatment regimen, EFS has improved from 25% to 87% for all B-cell NHL. The majority of patients had stage III and IV disease. Although the LMB regimens are toxic, the implementation is manageable provided good laboratory back up and supportive facilities are available.
    No preview · Article · Mar 2005 · Transfusion and Apheresis Science
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    ABSTRACT: The high regional incidence of hepatocellular carcinoma (HCC) in South Africa also may be present in children of the region, although the link to hepatitis B (HBV) appears less clear. The objective of this study was to assess the incidence and probable causes of HCC in South African children. Data were obtained from seven participating pediatric oncology units and from the tumor registry to review hepatic tumors in children in South Africa. One hundred ninety-four children (ages 0-14 years) presented with malignant primary hepatic tumors (1988-2003). One hundred twelve tumors (57%) were hepatoblastoma (HB), 68 tumors (35%) were hepatocellular carcinoma (HCC) (including 9 patients with the fibrolamellar variant, 6 of which occurred in black children), 10 tumors (5%) were sarcoma of the liver, and 4 tumors were lymphoma. The ratio of HB to HCC (1.67) was markedly lower compared with other reports, suggesting a greater prevalence of HCC. Correlation with population statistics indicated an incidence of 1.066 malignant liver tumors per year per 10(6) children age < 14 years (HB, 0.61 per 10(6) children; HCC, 0.39 per 10(6)). Two-thirds of patients with HCC were positive for HBV surface antigen (HBsAg), and HCC occurred mostly in black African patients (93%). The mean age of onset was 1.47 years for HB and 10.48 years for HCC. A preponderance of males (3.5:1.0) was noted in the HBsAg-positive group that was not reflected elsewhere. Serum alpha-fetoprotein (AFP) levels were raised both in patients with HB (100%; most AFP levels were very high) and in patients with HCC (69%), although 15% of patients with HCC had low or normal AFP levels. It appeared from the current results that HCC is more prevalent among children in South Africa compared with the children in more developed countries, although their rates were lower that the rates noted in adults. A collaborative approach will be required to improve their diagnosis and management.
    No preview · Article · Aug 2004 · Cancer
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    ABSTRACT: Objectives. To record the age-specific incidence rate (ASIR) for diagnosed acute lymphoblastic leukaemia (ALL) in coloured and white children aged 0 - 12 years in the Western Cape (WC). A retrospective population-based study using the 1991 population census to calculate the mean annual childhood population and the ASIR for ALL in the 0 - 4, 5 - 9 and 10 - 12-year age groups in rural and Cape Town metropolitan areas for the period 1983 - 1999. Odds ratios were calculated using EpiInfo 2000. Registry records of the paediatric cancer units at Tygerberg and Red Cross War Memorial Children's hospitals where all children with ALL in the WC were initially treated. All white and coloured children aged 0 - 12 years diagnosed as having ALL from 1983 - 1999. The ASIR by age and ethnic group in rural and metropolitan patients in the WC. The estimated annual childhood population in 1991 was 709 151 with 80.4% coloured and 19.6% white children, of whom 60% were resident in the Cape Town metropolitan area and 40% in the rural area of the WC. Of 246 children with ALL diagnosed in the period 1983 - 1999, 144 were male and 102 female. The ASIR in coloured children aged 0 - 4 years was 17.1/10(6) in the rural and 30.5/10(6) in the metropolitan area, compared with 55.7/10(6) and 56.2/10(6) respectively in white children. In the 5 - 9-year age group the ASIR in coloured children was 10.0/10(6) in the rural and 16.6/10(6) in the metropolitan area compared with 27.6/10(6) and 26.7/10(6) respectively in white children. The 10 - 12-year age group had comparable incidence rates in both populations and geographical areas. Only one case occurred within a 20 km radius of the Koeberg nuclear reactor. White children have an ASIR for ALL comparable to rates of diagnosis in the USA, while only half as many coloured children aged 0 - 9 years were diagnosed in both the rural and metropolitan areas. This contrast may indicate significant underdiagnosis of ALL in coloured children over the period in question. The change in health policy since 1994, which has improved access to primary health care, may improve the rate of diagnosis among coloured and black children.
    Full-text · Article · Aug 2004 · South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde
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    ABSTRACT: Burkitt lymphoma (BL) accounts for 50% of childhood cancer in Malawi. Lack of resources precludes the use of new successful treatment approaches such as the LMB 89 group B protocol, which cures >80% of children with stage III BL with high dose chemotherapy and matching supportive care. Our objective was to achieve a good cure rate in Murphy stage I-III BL with manageable toxicity in Malawi at a drug cost of <1000 US dollars per patient. The intensity and toxicity of the LMB 89 group B protocol was reduced and adapted to Malawi realities. All stages received the same treatment. Children with suspected BL in the period July 1997-November 1999 were subjected to abdominal ultrasound, a tumor biopsy and/or fine needle aspirate (FNA) and bone marrow (BM), cerebrospinal fluid (CSF), and peripheral blood examination. HIV seropositive children were excluded. Endpoints are projected event free survival (EFS) at minimum 1 year, blood and gastro-intestinal tract toxicity, and risk for and severity of infections. Forty-four children were eligible for treatment and analysis. Their median age was 7.2 years, M:F ratio 1.4:1 with 10 stage I, 5 stage II, and 29 stage III patients. Projected Kaplan-Meier EFS for all was 57% (CI 41-73) at 1 year with 90% EFS in stage I and 52% EFS in stage III. The survival curve remained stable at 500 days. Toxicity and delays in appropriate supportive care contributed to ten deaths during treatment. Local recurrent tumor caused five and CNS recurrence one death. Two children died from progressive disease. The incidence of severe (grade 3 and/or 4) hematologic toxicity varied from 13% to 36%, gastro-intestinal toxicity (GIT) from 2% to 17%, and infections from 7% to 41% per chemotherapy module. It is possible to administer less intense and less costly multiagent chemotherapy to children with BL in a developing society with acceptable EFS rates. Adequate supportive care of the at-times associated severe toxicity must be made available to better the results.
    No preview · Article · Dec 2003 · Medical and Pediatric Oncology
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    ABSTRACT: To record the number of haemophilicas aged 0-18 years in the Western Cape (WC), what event led to the diagnosis, the level of clotting factor, treatment, functional status of their joints and impact of the disease on the family. A prospective study of patients registered with the South African National Haemophilia Registry and new patients, utilising the patients' paediatricians, hospital records, patient and guardian interviews, physical examination and provincial nurse haemophilia co-ordinators. Haemophilia care centres at the three WC academic hospitals, regional hospitals and homes of patients. Two elective medical students, MHH and JJH, collected the information. All boys with confirmed haemophilia A or B in the WC. Events that led to diagnosis, degree of haemophilia, use of clotting factor, functional status, and effect on family. Of 78 patients (59 haemophilia A, 19 haemophilia B) identified, 49 could be studied. Forty-three per cent had severe, 29% moderate and 22% mild disease (6% unknown). Family history was present in 49%, but led to diagnosis in only 12%. The most common first symptoms were subcutaneous and mucosal bleeding. Delay in diagnosis varied from 0 to 9 months. Twenty-nine per cent of guardians were suspected of child abuse. RSA produced clotting factor was used 'on demand' in 73% of patients, for periodic prophylaxis in 20% and as continuous prophylaxis in 7%. Joints were functionally restricted in 43% of patients. The majority of guardians (59%) said the disease had a major impact on the family. The diagnosis of haemophilia in children with a positive family history was often delayed. Haemophilia causes significant morbidity in our patients and their families.
    Full-text · Article · Nov 2003 · South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde
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    ABSTRACT: Between 1991 and 1997, limited funding at times restricted available treatment for children with Burkitt lymphoma (BL) to cyclophosphamide (CPM) monotherapy at Lilongwe Central Hospital, Malawi. Our objective was to assess long-term survival in Malawian children with Burkitt lymphoma (BL) who had received one or more treatments with intravenous CPM at 40 mg/kg/dose at 14-day intervals. The study population consisted of 92 children in whom BL had been confirmed on fine needle aspirates (FNA), a home address had been documented on discharge from hospital, and the treatment records could be verified. Only the clinical site(s) of disease had been recorded. The M:F ratio was 1.4 and median age 8 years. A clinical officer on motorcycle attempted to locate the given addresses and interview parents or other sources. In 19 patients, the address was incorrect. Of 73 evaluable patients, 40 children are alive at a mean follow-up time of 59 (range: 29-104) months. The survival rate was 63.5% in 52 children with BL of the head only, and 33.3% in 21 children with primary disease involving the abdomen or other sites. Survivors had received a median number of 6 (range: 1-12), non-survivors 4 (range: 1-12), and untracable children 3 (range: 1-11) courses of CPM. We confirmed that CPM could cure children with facial and abdominal BL. The unavoidable bias in the selection of patients and the variable amount of CPM given, precludes accurate survival estimates. A prospective study with proper staging, assessment of FNA, marrow and cerebrospinal fluid with modern techniques, a standard treatment protocol, and adequate follow-up will better define the current therapeutic value of CPM monotherapy. CPM can be purchased at about 3 US dollars per 500 mg.
    Full-text · Article · Jan 2003 · Medical and Pediatric Oncology
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    ABSTRACT: Hereditary spherocytosis (HS) is an inherited haemolytic anaemia, characterized by spheroidal, osmotically fragile red blood cells. This disorder exhibits heterogeneity in terms of both clinical severity and underlying molecular defect. We have studied a South African Cape Coloured individual with severe HS owing to a band 3 deficiency caused by two mutations, occurring in trans, in the band 3 gene: a novel variant that we have designated band 3 Cape Town and a previously described mutation, band 3 Prague III. Analysis of erythrocyte membrane proteins indicated a deficiency of both band 3 and protein 4.2, as well as a decreased functional capacity of band 3 to transport anions. Band 3 Cape Town is defined by a GAG-->AAG point mutation at codon 90, substituting a glutamic acid with a lysine in the cytoplasmic domain of the molecule, while band 3 Prague III is a codon 870 CGG-->TGG point mutation, replacing an arginine with a tryptophan in the transmembrane region of band 3. mRNA is transcribed from both mutant alleles, implying that mutant proteins are synthesized, but are either degraded prior to membrane incorporation or insertion is impaired. We conclude that the combination of these two mutations exacerbated the clinical presentation of the proband.
    Preview · Article · Jun 2001 · British Journal of Haematology

Publication Stats

545 Citations
69.61 Total Impact Points


  • 1990-2012
    • Stellenbosch University
      • Department of Paediatrics and Child Health
      Stellenbosch, Province of the Western Cape, South Africa
  • 1986-2011
    • Tygerberg Hospital
      Kaapstad, Western Cape, South Africa