Genetic analysis and functional characterization of prothrombins Corpus Christi (Arg382-Cys), Dhahran (Arg271-His), and hypoprothrombinemia.

The structural abnormalities and functional characteristics of dysfunctional prothrombin variants in two new kindreds have been determined. Prothrombin Corpus Christi (family 1) was purified and found to have markedly reduced fibrinogen clotting activity, yet normal amidolytic and near-normal platelet aggregating activity. A transition (C to T) at nucleotide position 8885, present in the heterozygous form in affected family members, resulted in the substitution of Cys for Arg 382. This substitution results in the loss of a positive charge within the fibrinogen-binding exosite of thrombin, thus accounting for the observed functional defect. A heterozygous C to T transition was also present at position 19994 in other family members with a hypoprothrombinemic phenotype. This mutation results in the replacement of Gln 541 (CAA) by a premature stop codon (TAA). Prothrombin Dhahran (family 2) was found to have markedly reduced fibrinogen clotting activity, but normal amidolytic activity. Affected family members were found to have a G to A transition at nucleotide position 7312 resulting in the substitution of His for Arg 271. This substitution results in the abolition of a factor Xa cleavage site, yielding meizothrombin rather than thrombin, on activation of prothrombin Dhahran by factor Xa. All but one of the above mutations occur at CpG dinucleotides, thus further supporting the observation of a high incidence of CpG transitions in hereditary dysprothrombinemia. The significant bleeding tendencies of individuals homozygous for prothrombin Dhahran (prothrombin clotting activity 5% to 7%) contrast sharply with the absence of significant chronic bleeding in the proband expressing prothrombin Corpus Christi (prothrombin clotting activity 2%). Our findings underscore the capacity of thrombin to contribute to clinical hemostasis by mechanisms other than its fibrinogen clotting activity.

An epidemic of aplastic crisis caused by human parvovirus B19.

Human parvovirus B19 has been associated with several diseases. Aplastic crisis in patients with chronic hemolytic anemia, erythema infectiosum, hydrops fetalis and arthritis are among the common diseases caused by this virus infection. In the period between July, 1991, and March, 1992, 48 patients with aplastic crises were hospitalized at Saudi Aramco-Dhahran Health Center, Dhahran, Saudi Arabia. Forty-six patients had homozygous sickle cell disease, one had hemoglobin H disease and one had hereditary elliptocytosis. Evidence of recent human parvovirus infection was present in 91% of the cases. Leukopenia was present in 21%, neutropenia in 27% and thrombocytopenia in 42%. This differs from previous reports in which red blood cell aplasia causing anemia was the only hematologic finding reported in most patients. There were no cases of erythema infectiosum in either the patients or the community during the epidemic and the reason for this phenomenon is not obvious. The almost limited occurrence of aplastic crisis in patients with sickle cell disease in a population with a high incidence of other types of chronic hemolytic anemias is of interest.

Unusual presentation of meningococcal infection.

Infection with Neisseria meningitidis usually results in life-threatening septicemia and/or meningitis. Occasionally, howerver, infection may be mild or localized. Awareness of this fact is essential to avoid delays in diagnosis, management and prophylaxis. Three cases are presented with localized or mild presentation. A 40-day-old male with purulent conjunctivitis, a six-year-old male with peritonitis and a nine-year-old with C5 deficiency with Neisseria meningitidis bacteremia who presented with a one day history of fever, but was not toxic, and was treated with oral antibiotics. However, he returned with a clinical picture of systemic infection. Based on these three cases, we suggest an aggressive diagnostic, therapeutic and prophylactic approach whenever meningococcal infection is strongly suspected.

Acute splenic sequestration together with aplastic crisis caused by human parvovirus B19 in patients with sickle cell disease.

Three children with homozygous sickle cell disease, 22 months and 8 and 10 years of age, had clinical and hematologic manifestations of aplastic and splenic sequestration crisis simultaneously. They had an acute drop in hemoglobin level (16, 20, and 45 gm/L), reticulocytopenia (0.1%, 0.6%, and 0.3%), and sudden splenic enlargement. Evidence of recent parvovirus infection was demonstrated.

Agnogenic myeloid metaplasia in children.

Agnogenic myeloid metaplasia is a chronic myeloproliferative disorder characterized by splenomegaly, leukoerythroblastosis, extramedullary hematopoiesis, teardrop-shaped red blood cells, and fibrosis of the bone marrow. It is a disease of adults, with only one case report in the pediatric literature. The symptoms of the patient in this case clearly fit the diagnostic criteria of this disease. Myelofibrosis in children is usually of the acute type, presenting in infancy and running a fulminant, fatal course with minimal or mild splenomegaly. Red blood cells are usually normal on morphologic examination. Three infants, including two siblings, presented at ages 9, 10, and 16 months with clinical and laboratory findings consistent with agnogenic myeloid metaplasia. The occurrence of the disease in these siblings is suggestive of an autosomal recessive mode of inheritance.

Comprehensive newborn screening program: ARAMCO experience, the national need and recommendations.

Comprehensive screening programs for congenital diseases of newborn infants are lacking at a national or regional level. A comprehensive newborn screening program modified to the needs and resources available was established in ARAMCO Dhahran Health Center. This program includes screening for congenital hypothyroidism, phenylketonuria, abnormal hemoglobins, glucose-6-phosphate dehydrogenase deficienc, and blood group incompatibilities. Several problems were encountered during the operation which required several modifications of the program. The organization and procedures of the program are described. Since the program was started in 1980, more than 70,000 newborn infants have been screened. Valuable epidemiological data have been collected and necessary information for direct clinical use was obtained. A national program to screen all neonates in the Kingdom of Saudi Arabia is achievable and urgently needed. Recommendations based on ARAMCO experience are given.

Screening for glucose-6-phosphate dehydrogenase deficiency can prevent severe neonatal jaundice.

Infants with the severe variant of glucose-6-phosphate dehydrogenase (G6PD) deficiency may develop hyperbilirubinaemia sufficiently severe to cause kernicterus and death, acute haemolysis on exposure to oxidant stress, congenital non-spherocytic haemolytic anaemia and, rarely, increased susceptibility to bacterial infection. In spite of these potential problems, G6PD deficiency is often not included among screening programmes for inherited disorders. In a comprehensive screening and educational programme, we tested around 34,000 infants for G6PD deficiency. Of the total group, 18.4% (24.5% boys and 11.8% girls) were deficient. Forty-two of the 6246 (0.67%) G6PD-deficient infants required exchange transfusion. None of them developed kernicterus. By contrast, of 4755 infants who had not been screened because they were born at home, three developed kernicterus. In addition, four G6PD-deficient infants had developed kernicterus in the 20-month period prior to the screening programme. None of the hyperbilirubinaemic infants had blood group incompatibility or any other identifiable cause of hyperbilirubinaemia. To avoid this disastrous result, we believe that neonatal screening for G6PD deficiency, together with a comprehensive education programme, is advisable in those parts of the world where the severe variant of G6PD deficiency is prevalent.

Acute splenic sequestration crises in Saudi children with sickle cell disease.

Sickle cell disease (SCD) is a common disease in the Eastern Province of Saudi Arabia. Twenty per cent of the population have sickle cell trait and 1.75% have SCD. In the first 2 years of life, infection, hand-foot syndrome and acute splenic sequestration crisis (ASSC) are the most common complications of this disease. The classical characteristics of an ASSC, the subject of this paper, are sudden and rapid enlargement of the spleen, secondary to the massive pooling of red blood cells in the splenic sinusoids in a functioning spleen. Less common minor attacks of ASSC have been described recently. An ASSC is one of the most common causes of death in infants with SCD. The underlying cause and the precipitants of attacks of ASSC remain unknown. Seventeen children with ASSC were seen. Clinically, they had minor ASSC; three developed hypersplenism and four underwent splenectomy for recurrent attacks of ASSC. None of these 17 children had the classical ASSC described in black children where peripheral circulatory shock is encountered.

Incidence and causes of sepsis in glucose-6-phosphate dehydrogenase-deficient newborn infants.

To determine the susceptibility to sepsis in newborn infants deficient in glucose-6-phosphate dehydrogenase (G6PD), we screened 33,943 Saudi Arab infants. Deficiency of G6PD was found in 18%. Sepsis was determined by the presence of clinical signs of sepsis and confirmed by positive blood cultures. Sepsis was documented in 75 infants (2.2/1000). The incidence of sepsis was significantly higher in 6138 G6PD-deficient infants (3.4/1000) than in the 27,805 with normal G6PD activity (1.9/1000; p less than 0.02). The incidence of catalase-positive organism sepsis was higher in G6PD-deficient infants (2.9/1000) compared with those with normal G6PD activity (1/1000; p less than 0.0002), whereas the incidence of catalase-negative organism sepsis did not differ (p less than 0.2). Deficiency of G6PD was more common in infants with late sepsis (46%) than in those with early sepsis (21%) and in all infants screened (18%) (p less than 0.03 and p less than 0.001, respectively). We conclude that neonates with G6PD deficiency are more susceptible to late sepsis and to infection with catalase-positive organisms. The exact mechanism for the increased susceptibility is not clear, but a partial explanation could be lack of leukocyte bactericidal activity associated with G6PD deficiency, and an increased susceptibility to infection caused by hyperferremia resulting from lysis of G6PD-deficient erythrocytes.

Nasopharyngeal Hodgkin's disease with intracranial extension in a child.

Childhood Hodgkin's Disease rarely involves the nasopharynx or the brain. This is a report of a 12-year-old boy who presented with a 3-month history of headache, diplopia, dizziness, and early morning vomiting. Computerized axial tomography (CT) scan revealed a nasopharyngeal mass with intracranial extension through the skull base. Biopsy of the nasopharyngeal mass and an upper cervical lymph node was consistent with Hodgkin's disease of mixed cellularity. This, to the author's knowledge, is the first report of a child having the combination of nasopharyngeal and intracranial involvement in Hodgkin's disease.

Acute cholestatic jaundice in children with sickle cell disease: hepatic crises or hepatitis?

Differentiating acute cholestatic jaundice resulting from hepatic vasoocclusive crises and hepatitis in children with sickle cell disease can be difficult. Both conditions result in hyperbilirubinemia, mainly of the conjugated type, and in elevation of serum transaminases. Five children with sickle cell disease, acute severe cholestatic jaundice and negative serology for hepatitis A and B presented in good general condition, with modest elevation of serum transaminases, and had an early uneventful recovery. Five children with sickle cell disease and serologically proved hepatitis A infection were sicker, exhibited a similar elevation of bilirubin concentration with marked elevation of the serum transaminases and recovered more slowly. The clinical course and outcome of hepatitis A in children with sickle cell disease was similar to that of hepatitis A in normal children. Unlike early reports acute cholestatic jaundice in our patients with sickle cell disease, whether caused by hepatitis or by hepatic vasoocclusive crises, was found to be benign with an uneventful recovery.

Cholestatic jaundice with urinary tract infection in a child with acute lymphoblastic leukaemia.

The syndrome of cholestatic jaundice in association with urinary tract infection with normal or slightly elevated liver enzymes has been reported mainly in newborns and infants below 2 months of age. The relative immaturity of the infant's liver and its sensitivity to bacterial endotoxins may explain the occurrence of this syndrome in this age group. A similar syndrome has been reported in adults with severe non-hepatic bacterial infection, including some with urinary tract infection. However, only three case reports in older children could be found. In this report, the case of a 4-year-old girl with acute lymphoblastic leukaemia, who presented with cholestatic jaundice with normal liver enzymes and urinary tract infection, is described. Treatment with antibiotics resulted in resolution of the jaundice and potentially hepatotoxic drugs were used for the treatment of leukaemia with no problems. Two adult patients with acute leukaemia, non-hepatic bacterial infection and cholestatic jaundice have been reported; both died shortly after diagnosis.

Hyperostosis with hyperphosphatemia: a case report and review of the literature.

This is a report of a 6-year-old girl with the rare syndrome of hyperostosis with hyperphosphatemia. Only eight cases have been previously reported. The main features of this syndrome are repeated attacks of bone pain and swelling, the radiologic finding of periosteal reaction with cortical hyperostosis, and the laboratory finding of increased serum phosphorus level with normal serum calcium and parathyroid hormone levels. The purpose of this article is to review the clinical picture, laboratory and radiological findings, and the differential diagnosis.

Beneficial effect of blood transfusion in children with sickle cell chest syndrome.

Reports in the 1970s suggested that acute chest syndrome (ACS) in children with sickle cell disease is usually due to bacterial infection. Studies in adults and more recently in children, however, showed that proved bacterial infection occurs in a minority of these patients and that vascular occlusion is the main pathologic process. In a retrospective study of 32 episodes of ACS in children, a definite bacterial infection was found in 3% (one patient), possible bacterial infection in 11% (four patients), and a possible mycoplasma in 13% (five patients). With the intent to dilute sickle cells, 23 patients received blood transfusion within 24 hours after hospital admission; all showed a dramatic clinical and roentgenographic improvement. Of the nine patients who did not receive a transfusion after hospital admission, the conditions of five patients deteriorated but improved after "late" transfusion; three patients showed slow improvement, and only one patient improved within 48 hours. From this we conclude that vascular occlusion might be the main process in ACS and that early blood transfusion may be valuable in shortening the course and decreasing mortality. The low hemoglobin value at presentation in our patients makes dilution of sickle cells possible by packed red blood cell transfusion rather than exchange transfusion.