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Voskoboinik, I., Thia, M. C. & Trapani, J. A. A functional analysis of the putative polymorphisms A91V and N252S and 22 missense perforin mutations associated with familial hemophagocytic lymphohistiocytosis. Blood 105, 4700-4706

Cancer Immunology Program, Peter MacCallum Cancer Centre, Locked Bag 1, A'Beckett St, Melbourne, VIC 8006, Australia. <>
Blood (Impact Factor: 10.43). 07/2005; 105(12):4700-6. DOI: 10.1182/blood-2004-12-4935
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ABSTRACT Up to 60% of cases of the autosomal recessive immunodeficiency hemophagocytic lymphohistiocytosis (HLH) are associated with mutations in the perforin (PRF1) gene. In this study, we expressed wild-type and mutated perforin in rat basophil leukemia cells to study the effect on lytic function of the substitutions A91V and N252S (commonly considered to be neutral polymorphisms) and 22 perforin missense substitutions first identified in HLH patients. Surprisingly, we found that A91V perforin was expressed at reduced levels compared with wild-type perforin, resulting in partial loss of lytic capacity. In contrast, expression and function of N252S-substituted perforin were normal. Most HLH-associated mutations resulted in protein degradation (probably due to misfolding) and complete loss of perforin activity, the exception being R232H, which retained approximately 30% wild-type activity. Several other mutated proteins (H222Q, C73R, F157V, and D313V) had no detectable lytic activity but were expressed at normal levels, suggesting that their functional defect might map downstream at the level of the target cell membrane. One further perforin substitution identified in an HLH patient (V183G) was normally expressed and displayed normal lysis. This report represents the first systematic functional analysis of HLH-associated missense mutations and the 2 most common perforin polymorphisms.

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    • "A second, more common outcome (n = 14) was presynaptic dysfunction, which we have previously defined as reduced expression and/or PRF degradation or truncation in the RBL cells (Voskoboinik et al., 2004). As was observed previously with FHL-associated mutations (Ishii et al., 2005; Voskoboinik et al., 2005b), this group of substitutions invariably led to a marked loss of function (Table S1). Most commonly, presynaptic dysfunction occurred at residues that showed extremely high conservation between species as divergent as humans and fish (for instance, residues 189, 220, 221, 231, or 239), presumably because they are critical for protein folding during its biosynthesis. "
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    • "was homozygous for the novel missense mutation c . 112G4A ( Val38Met ) and homozygous for the known mutation c. 272C4T ( Ala91Val ) , which was initially described as a nonpathogenic variant [ Feldmann et al . , 2002 ] but was later proposed to contribute to the disease [ Busiello et al . , 2004 ; Clementi et al . , 2002 ; Trambas et al . , 2005 ; Voskoboinik et al . , 2005 ] . Interestingly , the patients with mutations in PRF1 included two with a very - late - onset form of the disease ( Patients 17 and 18 ) . They were compound heterozygous for missense mutations and an in - frame deletion , respectively . In total we detected PRF1 mutations in three of 23 patients from Germany , 14 of 32 of Turkish ori"
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