Somatic gene therapy for phenylketonuria and other hepatic deficiencies

Summary Gene therapy is the delivery of genetic material to specific cell types of an organism to alter its physiology or function. This technology is being explored as a means of treating diseases caused by deficiencies of hepatic gene products. The two diseases being used as models for hepatic gene therapy are classical phenylketonuria (PKU) and haemophilia B. Vectors derived from adenoviruses can be used to completely correct these diseases in animal models. The phenotypic correction generated in these studies is transient, and cannot be duplicated by vector readministration. The transient nature of transgene expression results from the destruction of the virally-transduced cells by a cellular immune response directed against the late viral gene products that are also expressed in the target cells. The inability to repeatedly administer virus is caused by a humoral immune response directed against viral proteins present at the time of infusion. If the host immune response is suppressed, transgene expression can persist for 6 months or more. These findings suggest that host immunomodulation in combination with further modification of the adenoviral vector to reduce or eliminate late viral gene expression may permit long-term expression of potentially therapeutic gene products in mammalian liver.     

Haplotypes and mutations of the PAH locus in Egyptian families with PKU

A high degree of molecular heterogeneneity at the phenylalanine hydroxylase (PAH) locus was established by examining RFLP haplotypes and PAH mutations in the families of 13 Egyptians with phenylketenouria (PKU). Thirteen different haplotypes were unequivocally determined in these kindreds. Haplotypes 1.8, 3.9, 4.3, 7.8, 22.11, 27.6, and 52.8 were found segregating with normal chromosomes, whilst haplotypes 1.8, 5.9, 23.8, 32.8, the newly assigned 73.9, and two as yet incomplete but novel haplotypes were found segregating with the mutant chromosomes. There was no particular preference for a single haplotype among normal or mutant chromosomes. Nine different mutations were also identified among the 26 alleles. IVS 10nt11g (8/26), IVS 2nt5g-c (4/26), R261Q (3/26), R176X (2/26), Y206D (2/26), S231P (2/26), Y198fs [593-614del22bp]; (2/26), G46fs [136/137delG]; (1/26), and E178G (1/26). Six of these mutations (IVS 2nt5g-c, R176X, Y198fs, R261Q, S231P, and IVS 10nt11g) are common to other Mediterranean populations. Two mutations not previously reported in the Mediterranean basin were also observed (Y206D and G46fs). These intriguing preliminary findings confirm IVS 10nt11g as a major mutation among Mediterranean mutations and demonstrate the need for a more comprehensive study of Arab populations to confirm the uniqueness of the two novel mutations to the Egyptian population.     

Quantitative study of the immunoglobulin-containing cells in trephine samples of bone marrow

Immunoglobulin (Ig) was demonstrated in paraffin sections of 12 trephine bone marrow biopsies by means of the unlabelled antibody peroxidase-antiperoxidase (PAP) method. The Ig-containing cells, which were counted with the Reichert-Jung (Kontron) MOP-AMO₃ user-controlled image-analyser, were found to constitute approximately 4·2% of all the nucleated cells in the marrow, a figure significantly higher than those reported by previous workers.