Profound biotinidase deficiency caused by a point mutation that creates a downstream cryptic 3' splice acceptor site within an exon of the human biotinidase gene.

Biotinidase recycles the vitamin biotin from biocytin upon the degradation of the biotin-dependent carboxylases. We have identified a novel point mutation within the biotinidase gene that encodes the signal peptide in two unrelated individuals with profound biotinidase deficiency. Sequence analysis of genomic DNA from these individuals revealed a G to A transition (G100-->A) located 57 bases downstream of the authentic splice acceptor site in exon B. Although this mutation predicts a G34S substitution, it also generates a 3' splice acceptor site. Sequence of the PCR-amplified cDNA from the homozygous child revealed that all the product was shorter than that of normal individuals and was the result of aberrant splicing. The aberrantly spliced transcript lacked 57 bases, including a second in-frame ATG, that encode most of the putative signal peptide and results in an in-frame deletion of 19 amino acids. The mutation results in failure to secrete the aberrant protein into the blood. This is the first reported example in which a point mutation creates a cryptic 3' splice acceptor site motif that is used preferentially over the upstream authentic splice site. The preferential usage of the downstream splice site is not consistent with the 5'-3' scanning model, but is consistent with the exon definition model of RNA splicing.

Decreased ferritin levels, despite iron supplementation, during erythropoietin therapy in anaemia of prematurity.

Erythropoietin (rHuEPO) therapy has been shown to be beneficial in preventing and treating anaemia of prematurity and to decrease the need for blood transfusions. There is, however, only scanty data on the effect of rHuEPO therapy on iron metabolism. We studied 29 preterm infants (age 34 +/- 14 days) who were randomly assigned to receive either rHuEPO 900 U kg-1 week-1 with 6 mg kg-1 day-1 of iron for 4 weeks (n = 15) or no therapy. The following parameters were evaluated and compared between and within groups at the beginning, during and at the end of the study: Haematocrit (SI), reticulocytes (10(9) micrograms l-1), serum ferritin (microgram 1-1) and iron (mumol l-1). The results were as follows. At the baseline, erythropoietin levels were similar in both groups: 7.2 +/- 5.6 versus 6.2 +/- 3.2 mU ml-1 (NS). In the treated infants the haematocrit remained stable during the study and was significantly higher than in the control group by the end of the study: 0.34 +/- 0.03 versus 0.28 +/- 0.05 (p = 0.001). rHuEPO therapy increased the reticulocyte count from 130 +/- 70 to 430 +/- 200 (p = 0.0002). However, rHuEPO therapy depleted both serum ferritin and iron levels from 321 +/- 191 to 76 +/- 58 micrograms l-1 (p = 0.04) and from 18 +/- 5 to 13 +/- 4 mumol l-1 (p = 0.03), respectively. We conclude that rHuEPO therapy prevented anaemia and its sequelae; however, serum ferritin and iron levels were depleted. We suggest that the effect of rHuEPO may be further increased by higher iron supplementation.

Epidemiological, clinical and microbiological features of shigellosis among hospitalized children in northern Israel.

The epidemiological, clinical, and bacteriological aspects of shigellosis were studied in a population of hospitalized children in northern Israel. During the 6-year period 1987-92, 262 children were hospitalized due to shigella infection. Shigellosis represented 10% of pediatric admissions for diarrhea. Admissions for the disease peaked during the summer and autumn. The median age of the patients was 3 years. Shigella sonnei was isolated in 74% of patients and S. flexneri in 21%, compared with relative frequencies of 87% and 10%, respectively, in the non-hospitalized population of the area, detected during the same period (p < 0.001). Shigella sonnei represented 82% of isolates of hospitalized Jewish patients but only 60% of hospitalized Arab children, many of whom live in poverty and overcrowding (p < 0.001). Shigella flexneri was particularly frequent among hospitalized infants, and was associated with Arab origin, large families and residence in agricultural settlements. Duration of hospitalization was 4.7 +/- 2.3 days for S. sonnei infections and 5.8 +/- 3.6 days for S. flexneri (p < 0.005). No cases of shigella sepsis, hemolytic uremic syndrome, or fatalities were observed. Overall 37% of all shigella isolates from hospitalized children were resistant to ampicillin, 71% to cotrimoxazole, 28% to both and 13% were resistant to > or = 3 different drugs. It is concluded that shigellosis is an important cause of hospitalization in northern Israel. Resistance to antimicrobial drugs is widespread among all Shigella spp. Although S. sonnei is the most common species, S. flexneri is particularly frequent in infants.