Archetypal and new families with Alexander disease and novel mutations in GFAP.

OBJECTIVE: To describe genetic analyses of the 2 most thoroughly studied, historically seminal multigenerational families with Alexander disease described prior to the identification of GFAP as the related gene, as well as 1 newly discovered family. DESIGN: Clinical histories were obtained and DNA was analyzed from blood, cheek epithelial cells, or fixed paraffin-embedded surgical samples. SUBJECTS: Affected and unaffected adult members of 3 families and affected children were included. MAIN OUTCOME MEASURES: Mutations in GFAP and behavior of mutant protein in cellular transfection assays. RESULTS: Family A contains 4 siblings in whom we found a novel p.Ser247Pro mutation that was paternally inherited. The phenotypes of these siblings include 1 unaffected adult, 1 individual with juvenile-onset disease, and 2 individuals with adult-onset disease. Family B spans 4 generations, including the first described patient with adult-onset disease originally reported in 1968. Analysis of members of the later generations revealed a novel p.Asp417Ala mutation. Family C contains 3 generations. We detected a novel p.Gln426Leu mutation that, to our knowledge, is the farthest C-terminal mutation known. CONCLUSIONS: These families display clear evidence of variable phenotypes but do not support recessive inheritance. While germline mosaicism cannot be excluded for 1 family (A), we propose that for genetic counseling purposes the risk of germline mosaicism should be described as less than 1%.

Potentiation of regulatory volume decrease by a p2-like receptor and arachidonic acid in american alligator erythrocytes.

This study examined the role of a P2 receptor and arachidonic acid (AA) in regulatory volume decrease (RVD) by American alligator red blood cells (RBCs). Osmotic fragility was determined optically, mean cell volume was measured by electronic sizing, and changes in intracellular Ca(2+) concentration were visualized using fluorescence microscopy. Gadolinium (50 µM), hexokinase (2.5 U/ml), and suramin (100 µM) increased osmotic fragility, blocked volume recovery after hypotonic shock, and prevented a rise in intracellular Ca(2+) that normally occurs during cell swelling. The P2X antagonists PPADS (50 µM) and TNP-ATP (10 µM) also increased fragility and inhibited volume recovery. In contrast, ATPγS (10 µM), α,ß-methylene-ATP (50 µM) and Bz-ATP (50 µM) had the opposite effect, whereas 2-methylthio-ATP (50 µM) and UTP (10 µM) had no effect. In addition, the phospholipase A(2) (PLA(2)) inhibitors ONO-RS-082 (10 µM), chlorpromazine (10 µM), and isotetrandrine (10 µM) increased osmotic fragility and blocked volume recovery, whereas AA (10 µM) and its nonhydrolyzable analog eicosatetraynoic acid (ETYA, 10 µM) had the reverse effect. Further, AA (10 µM), but not ATPγS (10 µM), prevented the inhibitory effect of a low Ca(2+)-EGTA Ringer on RVD, whereas both AA (10 µM) and ATPγS (10 µM) caused cell shrinkage under isosmotic conditions. In conclusion, our results are consistent with the presence of a P2-like receptor whose activation stimulated RVD. In addition, AA also was important for volume recovery.