Clinico-immunogenetic study on Egyptian multicase tuberculous families

Thirteen multicase Egyptian families (having more than one sib affected) with pulmonary tuberculosis have been studied. They include 26 parents (4 were tuberculous) and 53 sibs (30 tuberculous and 23 healthy). For all of them the following have been carried out: (a) Clinical, radiological, and bacteriological examination for diagnosis and evaluation of the disease severity; HLA-antigen determination using 9(A), 16(B) and 6(DR) antigens. The analysis of data revealed: (1) high incidence of tuberculosis among sibs in families having A2 B5 in their haplotypes compared to those having A2 X or B5 X--affected sibs with A2 B5 showed more severe manifestations than those having only one of the two antigens; (2) aggregation of HLA concordance among the sib pairs, both fully identical and haploidentical, while none of the sib pairs is non-identical; (3) Lod score studies showed linkage between the genetic control of susceptibility to pulmonary tuberculosis and HLA; (4) identity by descent study confirms the dominant pattern of transmission. The recommendation is that in a clinical setting of genetic counselling healthy individuals having either A2 or B5 antigens in their haplotypes should be vaccinated with BCG. Furthermore tuberculous patients having these HLA antigens should be managed aggressively, especially those having A2 B5 haplotypes in whom the disease is likely to run a severe course.

The meiotic stage of nondisjunction in trisomy 21: determination by using DNA polymorphisms

We have studied DNA polymorphisms at loci in the pericentromeric region on the long arm of chromosome 21 in 200 families with trisomy 21, in order to determine the meiotic origin of nondisjunction. Maintenance of heterozygosity for parental markers in the individual with trisomy 21 was interpreted as resulting from a meiosis I error, while reduction to homozygosity was attributed to a meiosis II error. Nondisjunction was paternal in 9 cases and was maternal in 188 cases, as reported earlier. Among the 188 maternal cases, nondisjunction occurred in meiosis I in 128 cases and in meiosis II in 38 cases; in 22 cases the DNA markers used were uninformative. Therefore meiosis I was responsible for 77.1% and meiosis II for 22.9% of maternal nondisjunction. Among the 9 paternal nondisjunction cases the error occurred in meiosis I in 2 cases (22.2%) and in meiosis II in 7 (77.8%) cases. Since there was no significant difference in the distribution of maternal ages between maternal I error versus maternal II error, it is unlikely that an error at a particular of maternal ages between maternal I error versus maternal II error, it is unlikely that an error at a particular meiotic stage contributes significantly to the increasing incidence of Down syndrome with advancing maternal age. Although the DNA polymorphisms used were at loci which map close to the centromere, it is likely that rare errors in meiotic-origin assignments may have occurred because of a small number of crossovers between the markers and the centromere.(ABSTRACT TRUNCATED AT 250 WORDS)

A new beta-thalassaemia frameshift mutation detected by PCR after selective hybridization to immobilized oligonucleotides

A previously undescribed mutation (-1, +3, codon 24) causing beta-thalassaemia was identified in an Egyptian patient. It consists in the concomitant deletion of a G in codon 24 and its replacement with the new trinucleotide CAC, thus resulting in the shift of the beta-globin reading frame. The sequence of the chromosome of interest was isolated from the homologous one by means of selective hybridization to an immobilized oligonucleotide. The presence of this mutation in the proband's family was confirmed by dot blot hybridization with an oligonucleotide probe.

Susceptibility to and severity of rheumatoid arthritis in multicase families

Fifteen sibships, each having two or more siblings affected by classical or definite RA were studied. They comprised 31 patients with RA (all in remission) and 21 normal siblings. The total severity index of RA was assessed by clinical and radiological indices. For all the patients the following investigations were carried out: (1) HLA antigens determination for nine antigens at A locus and 15 at B locus and 6 at DR locus; (2) rheumatoid factor. We found: (1) RA disease is genetically controlled and the responsible genes are linked to the HLA system; (2) association between seropositivity and DR4 and DR4/B27 genotypes; (3) significant effect of the genotype DR4/B27 on the age of onset; (4) association between the increase in disease severity both clinical and radiological and DR4/X and DR4/B27 phenotypes. Thus the genetic control is probably composed of two types of genes: disease susceptibility genes and disease severity genes linked to DR4/X and DR4/B27 phenotypes.

Immunogenetic susceptibility for post-schistosomal hepatic fibrosis

In 19 children with hepatic fibrosis as the result of continued schistosomiasis mansoni and 20 children without hepatic fibrosis, the following studies were carried out: HLA antigen typing for 30 antigens, immune response of T lymphocytes to schistosome antigen by measuring DNA synthesis evidenced by 3H-thymidine uptake, and measurement of total OKT3+, OKT4+, and OKT8+ cells using monoclonal antibodies. Patients with hepatic fibrosis were mostly high responders in contrast with those without fibrosis. High immune response and susceptibility to post-schistosomal hepatic fibrosis were associated with a high frequency of A2 and B12 antigens and a lack of DR2 antigens, while low response was associated with the presence of the DR2 antigen. The T4+:T8+ ratio showed increased suppressor proportions in patients with low immune response and/or with no hepatic fibrosis. We suggest an immunogenetic susceptibility for post-schistosomal hepatic fibrosis, probably controlled by HLA-linked genes via the suppressor T cells.

Immunogenetic study of the response to streptococcal carbohydrate antigen of the cell wall in rheumatic fever

An immunogenetic study of the response to streptococcal carbohydrate antigen of the cell wall was carried out on members of 15 multiplex families each having more than one sib affected with rheumatic heart disease. They comprised 30 parents and 61 sibs (32 with rheumatic disease and 29 without). Fifty healthy unrelated subjects served as controls. A history was taken and clinical examination carried out. Rheumatic activity was determined and HLA typing was carried out for nine A antigens, 15 B antigens, and six DR antigens. The immune response of lymphocytes to streptococcal polysaccharide antigen of the cell wall of group A beta haemolytic streptococci in vitro was studied by tritiated thymidine uptake. The results were statistically and genetically analysed. It was found that (a) all subjects with rheumatic disease were highly responsive to the streptococcal polysaccharide antigen of the cell wall, the sib pairs being mostly HLA identical; (b) all low responders had no rheumatic disease and their phenotypes were mostly different from those of the rheumatic member of their sib pair; (c) correlation of immune responsiveness (high or low) between HLA-identical sibs was significant, but insignificant between haplotype identical and non-identical sibs; (d) the gene responsible for high responsiveness to the streptococcal polysaccharide antigen of the cell wall is recessive and closely linked to HLA. In conclusion, it was found that exposure to pharyngeal infection with group A beta haemolytic streptococci may lead to acute rheumatic fever in those with an inherited recessive gene responsible for high responsiveness to the streptococcal polysaccharide antigen of the cell wall.

Evidence of HLA-linked susceptibility gene(s) in primary congenital glaucoma

The study included 82 individuals. Twenty-two were sporadic unrelated patients with Primary Congenital Glaucoma (PCG), and 60 were the members of 10 multiplex families. They were enrolled into two groups; GI:10 multiplex families; GII:32 unrelated patients with PCG (22 sporadic plus 10 probands of the multiplex families). The following were carried out for all the individuals: (1) detailed history; (2) ophthalmologic examination for diagnosis of PCG; (3) clinical examination to exclude any other disease; (4) HLA antigen typing using 30 antigens, 9 for A locus, 15 for B locus, and 6 for DR locus. Genetic and statistical analysis revealed the following: (1) significant association between HLA-B8 and PCG; (2) family studies revealed a susceptibility gene, probably recessive, predisposing to PCG; (3) this gene is linked to HLA, with strong linkage disequilibrium with B8.

A new beta-thalassemia mutation produced by a single nucleotide substitution in the conserved dinucleotide sequence of the IVS-I consensus acceptor site (AG----AA)

An Egyptian child with thalassemia major was found to carry two different haplotypes (I and VI) associated with two beta-thalassemic chromosomes. Analysis with several oligonucleotides and restriction enzymes, which identify the mutations most common in the Mediterranean area, allowed the identification of only one mutation, namely T----C at position 6 of the first intervening sequence (IVS-I). In order to characterize the other mutation the beta gene was amplified with polymerase chain reaction and sequenced. A G----A substitution was found at position 130 of the IVS-I which alters the conserved dinucleotide AG present in the consensus acceptor sequence, thus producing a beta (0)-thalassemia. This mutation was further confirmed by restriction analysis since it creates a new restriction site for the enzyme Afl II. It is concluded that this subject carries the IVS-I-6 mutation associated with haplotype VI, frequently observed in Mediterranean areas, and a new mutation at the acceptor site of the IVS-I, which has not been described before, associated with haplotype I. This thalassemic gene can be added to the list of mutations that can be identified by Southern analysis using Afl II.

Evidence of HLA-linked susceptibility gene(s) in respiratory distress syndrome

In a prospective study 101 newborns were enrolled into four groups: Group I included 38 unrelated newborns suffering from RDS and four sets of twin sibs (seven of whom had RDS; Group II included prematures free from RDS and any other disease; Group III included 21 newborns) delivered by C.S. and free from RDS and any other disease; Group IV included 20 infants of diabetic mothers free from RDS. HLA antigens were typed for all the newborns. The analysis of results could be summarized as follows. (1) Strong association between A3 antigen (RR = 19.4, WY2 = 59.8, S = 0.599) and B14 antigen (RR = 14.1, WY2 = 50.7, S = 0.489) and RDS. (2) HLA haplotypes were identical in twins sibs suffering from RDS and nonidentical in twins when one sib had RDS and the other is free. (3) The frequencies of A3 and B14 among the other three groups were insignificantly different from the general population and highly significantly low compared to RDS group. In conclusion, the development of RDS depends probably on the presence of susceptibility gene(s) in linkage disequilibrium with A3 and B14 antigens. Environmental factors, magnified by prematurity, in such susceptible newborns affect the production of surfactant leading to the development of RDS.

Spinal dysraphism: experience with 250 cases operated upon

During a period of 4 years (December 1983-December 1987) 250 children were operated upon by the authors. At the outpatient clinic of the New Children's Hospital 313 infants and children suffering a myelodysraphic lesion were seen, 63 of whom were not treated surgically owing to the presence of severe hydrocephalus in 16 cases and complete flaccid paraplegia with marked sphincteric disturbances in 47. All of the patients came from poor families. Malnutrition, many siblings per family, poor maternal care, and repeated pregnancies and abortions have added to the large incidence of such a handicap in Egypt. The clinical features, diagnosis, and management of 200 cases of spinal bifida aperta (SBA) and 50 of spina bifida occulta (SBO) are summarized. SBA cases were operated upon as soon as possible from the time of their presentation; their preliminary assessment included an exhaustive general, neurological, urological, and orthopedic examination; and investigations such as plain X-rays to the back and skull, CT scanning of the cranium, spinal myelogram, and metrizamide CT scanning to the back were performed. The surgical outcome is far from being satisfactory in the sense of producing an ambulatory, intelligent, healthy individual, especially in a meningomyelocele patient having a high-level lesion. The authors believe that there is still much to be done for these children marked by fate, and the neurosurgeon should be one among several other physicians devoted to the amelioration or at least the prevention of worsening, if possible, of the condition in such unfortunate and handicapped children.

Evidence of inherited susceptibility of increased streptococcal adherence to pharyngeal cells of children with rheumatic fever

The study included the members of 15 families, each having more than one sibling affected by rheumatic fever (RF). All the rheumatic individuals showed the sequelae of rheumatic carditis, but on clinical and laboratory evidence, the disease was inactive. Thirty normal unrelated individuals, having no rheumatic first-degree relatives, were studied as controls. The following investigations were carried out for all members: (1) history and clinical examination, (2) routine investigations of diagnosis, (3) HLA typing using 9-A, 15-B, 6-DR antigens, (4) adherence of group A streptococci to pharyngeal cells, an in vitro adherence assay. There were two types of strains; five RF-associated strains and two RF-unassociated strains. Statistical and genetic analysis revealed: (1) no significant difference between adherence of RF-associated and unassociated strains amongst controls; (2) significant increased avidity for adherence of RF-associated strains amongst rheumatic siblings compared to normal siblings and controls. There was no significant difference between the three groups using RF-unassociated strains; (3) HLA-haplotype concordance and 'N' measure showed that the avidity for adherence is probably inherited; (4) lod scores for linkage suggest a dominant susceptibility gene(s) closely linked to HLA and segregating in multiplex families.

Frequency and molecular types of deletional alpha-thalassemia in Egypt

The frequency of deletional alpha-thalassemia in the Egyptian population was estimated at 0.08 by DNA analysis of a newborn random sample. No alpha 0 determinants were found. The most frequent alpha+ determinant was the -alpha 3.7 type I in association with the medium allele at inter-zeta HVR. The -alpha 4.2 and alpha alpha alpha anti 3.7 arrangements were found at very low frequencies.

Studies of peripheral blood T lymphocytes in assessment of disease activity in rheumatic fever

The study included three groups of children: (a) 38 with active rheumatic fever (ARF) and active carditis; 21 seen during their first attack and 17 during recurrence of activity, (b) 47 with inactive rheumatic fever (IARF); the period since activity was less than 3 years in 31 cases and more than 3 years in 16 cases. Using monoclonal antibodies and T lymphocyte blast transformation induced by PHA, we found: (1) low total T lymphocytes, helper-inducer cells and helper-inducer/suppressor-cytotoxic ratio which persisted for years; and (2) reduced lymphoblast transformation in active disease.

Immune regulation dysfunction in chronic persistent hepatitis

The study included 19 children diagnosed clinically, biochemically, and by liver biopsy as having chronic persistent hepatitis. The following investigations were carried out: 1. detection of total T-lymphocytes, T-helper, and T-suppressor cells using monoclonal antibodies (OKT3, OKT4 and OKT8); 2. determination of HLA-A, B and DR antigens using the microcytotoxicity technique. The results were analysed in comparison with data from a normal control group. There are several important findings. First, low total T-lymphocytes with increased proportion of suppressor cells (P less than 0.001). Second, strong association between HLA-A1 antigen and CPH (Fisher exact = 0.000022). Third, significant association between the immunoregulatory dysfunction and A1 antigen (Fisher exact = 0.033). This observation suggests that a genetic component may influence susceptibility to CPH through an increased suppressor response.

Presumptive evidence for an immunosuppressor susceptibility gene, linked to HLA, in rheumatic fever

In a study of rheumatic carditis, 135 members of 21 multiplex families have been investigated, along with 60 normal unrelated control individuals. Circulating T-lymphocytes were reduced (as a percentage of total blood mononuclear cells) in all 'rheumatic' individuals, in 7 of 40 normal parents, and in 8 of 49 normal sibs. An immune response characterized by an increase in the proportion of suppressor T cells occurs in most individuals affected by rheumatic carditis and this change persists for a long time. Genetic analysis revealed three important points: 1. increased HLA haplotype sharing amongst the affected sib-pairs; 2. the possibility of using low circulating T-cell percentage as a marker of susceptibility; 3. presumptive evidence for a recessive susceptibility gene linked to HLA and responsible for the suppressor cell response.

Immunogenetic aspects of febrile convulsions

Thirty-nine mentally normal unrelated children diagnosed as having febrile convulsions were included in this study. The following have been carried out: (a) detailed anamnesis and clinical examination; (b) cerebrospinal fluid investigation; (c) EEG examination between attacks; (d) HLA-antigen determination; (e) estimation of serum IgA, IgG, IgM; and (f) counting of percent spontaneous E-rosette formation. The results were statistically compared to normal Egyptian controls. The results could be summarised as follows. (1) Only HLA-B5 antigen frequency is high among patients (chi 2c = 19.1, P less than 0.0001). Relative risk is 4.4 which shows significant association (WY2 = 29.145, P less than 0.0001) and etiologic fraction equals 0.377. (2) The means of IgA and E-rosette in the patients were significantly low (t = 3.46, P less than 0.01 and t = 3.92, P less than 0.001, respectively), (3) HLA-B5 is the only antigen with high frequency among the two groups of patients with low IgA and E-rosette (chi 2c = 11.9 and 18.2, respectively). (4) There is a significant association between B5 and low IgA (P less than 0.05) but not with low E-rosette (P greater than 0.05). The suggestion is that the genetic control of febrile convulsions is in linkage disequilibrium with HLA-B5, low IgA and low total T-cells. This altered immune function in otherwise normal children with febrile convulsions may predispose them to acute infections and high fever which precipitate convulsions.

Inherited immunoregulatory dysfunction in extrinsic bronchial asthma

We studied 119 members of 22 asthmatic multiplex families. Included were: 44 parents (seven were asthmatics), 48 asthmatics (23 were undergoing an attack at the time of sampling), and 27 normal siblings. The following investigations were carried out on all subjects: 1) detection of total T lymphocytes, helper cells, and suppressor cells, using monoclonal antibodies (OKT3, OKT4, and OKT8), 2) study of nonspecific T-lymphocyte blast transformation induced by PHA, and 3) HLA-A, B, and DR antigen determination using the microcytotoxicity technique. The results were compared with normal ranges and data for a normal group and statistically and genetically analyzed. They indicate that: 1) the number of T cells was low in asymptomatic asthmatics and normal in asthmatics in attack; 2) there were fewer helper and normal suppressor cells (that is, a low H:S ratio) in asymptomatic asthmatics, and a normal amount of helper and suppressor cells (a normal H:S ratio) in those experiencing an attack; 3) there was a percentage of lymphocyte transformation in both groups of asthmatics; 4) whereas the T-helper cells increased, there was no change in the number of suppressor cells during an attack, which points to deficient function of suppressor cells; 5) the disorder is inherited and the gene controlling this dysfunction is HLA-linked and probably dominant.

HLA antigens in multiplex families with isolated congenital heart disease

Twelve multiplex families with isolated congenital heart diseases (CHD) were included in the study. In 9 families the types of CHD in the living sibs were concordant and in the other 3 were discordant. All families were subjected to the following: (1) Pedigree construction, (2) clinical examination of the parents, affected and unaffected sibs, (3) investigations of patients, to establish the diagnosis, (4) chromosomal analysis for the patients, (5) HLA antigen typing for the parents, affected and unaffected sibs for 9 antigens at the A locus, 15 at B and 6 at the DR locus. The results can be summarized as: (a) sibs with two different types of CHD showed identical haplotypes; (b) the segregation of haplotypes among disease sibpairs is inconsistent with Mendelian segregation; (c) increased frequency of concordant HLA haplotypes among diseased siblings; (d) Morton's exact test revealed that the data best fit a hypothesis of a recessive susceptibility gene, linked to HLA.

HLA-antigens in the Egyptian population

HLA-A, -B and -DR markers were determined for 380 normal unrelated Egyptians of both sexes. Typing for 9 A-locus, 15 B-locus and 6 DR-locus alleles was done. Antigen, gene and haplotype frequencies and delta-values were estimated. The data obtained were statistically compared to those of Arabs at Gaza Strip, European and American Caucasians, American Blacks, African Blacks and Japanese (Orientals). The Egyptian genetic make-up was found to be heterogenous and some HLA markers differ significantly from that of other ethnic groups as well as Arabs from the Gaza Strip.

Enhanced response to the induction of sister chromatid exchange by gamma radiation in neurofibromatosis

The study included 8 unrelated patients with neurofibromatosis, and 10 unrelated normal and healthy persons as controls. Whole blood samples were divided into plastic T flasks and exposed at room temperature to gamma rays. The radiation dose was 36 rad/minute, and the doses delivered were 0, 75, 150 and 300 rad. The lymphocytes were cultured in (RPMI) 1640 tissue culture medium and autologous serum (20%). Phytohemagglutinin and bromodeoxyuridine (Brdu) (10 microM) were added at initiation of culture and harvesting was done 64 to 68 hours after culture initiation. Slides were coded, differential staining was done, and sister chromatid exchanges (SCEs) and aberrations (gaps, breaks, dicentrics, fragments and minutes) were counted. In the controls no significant increase in frequency of SCE has been found (P greater than 0.5). In the patients, the frequencies significantly increased with the increase of dose of irradiation (P less than 0.001). Furthermore, after irradiation, the incidence of gaps, breaks, and dicentrics were significantly increased in patients compared with controls. Moreover, the incidence increased with the increase in the dose of radiation. The results are discussed with a conclusion that the results add to the indication of a genetic predisposition to develop cancer in neurofibromatosis patients.

Improved erythrocyte survival with combined vitamin E and selenium therapy in children with glucose-6-phosphate dehydrogenase deficiency and mild chronic hemolysis

To study the antioxidant effect of high-dose vitamin E alone and in combination with selenium in patients with glucose-6-phosphate dehydrogenase deficiency with mild chronic hemolysis, 36 male children with such manifestations were enrolled consecutively into two equal groups. Group 1 received 800 IU vitamin E daily, and group 2 received 800 IU vitamin E in combination with 25 micrograms selenium. Hematologic status before and 2 months after treatment was evaluated. After treatment there was a significant change toward normal in both groups. The mean red cell half-life increased in group 1 from 16.9 to 22.8 days (P less than 0.01), and in group 2 from 15.6 to 24.3 days (P less than 0.01). A comparison of the mean difference of paired values in the two groups revealed a more significant increase in hemoglobin (0.9 +/- 0.1 gm/dl vs 1.2 +/- 0.2 gm/dl, P less than 0.05), hematocrit (2.4% +/- 0.4% vs 3.8% +/- 0.3%, P less than 0.05), and red cell half-life (5.9 +/- 3.0 days vs 9.1 +/- 4.4 days, P less than 0.01), and more significant reduction in reticulocytes (-0.7% +/- 0.2% vs -1.5% +/- 0.4%, P less than 0.01) in group 2. Clinical assessment and follow-up indicated no side effects related to the drugs.

HLA-antigens in Guillain-Barré syndrome

A microlymphocytotoxicity test determined serologically the frequency of HLA antigens in 32 patients with Guillain-Barré syndrome and in 234 healthy control subjects. The results demonstrated significantly increased frequencies of A3 and B8. The relative risk was estimated to be 9.6 and 4.6 for the A3 and B8 antigens, respectively. Study of the gametic association revealed weak positive linkage disequilibrium and biological association. The results are discussed, and it is concluded that the aberrant genetic make-up of the patients makes them more susceptible to develop the syndrome after exposure to the environmental factor(s).

Evidence of chromosomal instability in neurofibromatosis

Blood lymphocytes from six unrelated patients with neurofibromatosis and three normal controls were examined for their response to different doses (0, 75, 150, 300, 400 rad) of x-radiation, as measured by chromosome aberrations (gaps, breaks, dicentrics, centric rings, acentric ring, fragments, and minutes). Cytogenetic studies on phytohemagglutinin-stimulated cells revealed chromosomal instability in the neurofibromatosis lymphocytes as shown by the significant increase in the in the incidence of gaps, breaks and dicentrics. This increase paralleled the increase in the dose of irradiation. The significance of these findings is discussed.

HLA-antigens and tuberculosis in the Egyptian population

Peripheral blood lymphocytes from 42 unrelated Egyptian patients with tuberculosis and 156 healthy persons were HLA phenotyped for the A,B and DR loci using the NIH lymphocytotoxicity tests. Statistical analysis of the results showed that A2 and B5 had significantly increased frequencies among patients with tuberculosis compared with the controls. Patients with A2 had more severe disease than did patients without A2 and the number with B5 antigen was less than those without the antigen. This observation suggests that A2 and B5 may influence susceptibility to tuberculosis, but not the course of the disease. Furthermore, a linkage disequilibrium was found between A2 and B5 antigen among tuberculous patients, but their association bore no relation to the severity of the disease.