Griscelli syndrome: characterization of a new mutation and rescue of T-cytotoxic activity by retroviral transfer of RAB27A gene.
Griscelli syndrome (GS) is caused by mutations in the MYO5A (GS1), RAB27A (GS2), or MLPH (GS3) genes, all of which lead to a similar pigmentary dilution. In addition, GS1 patients show primary neurological impairment, whereas GS2 patients present immunodeficiency and periods of lymphocyte proliferation and activation, leading to their infiltration in many organs, such as the nervous system, causing secondary neurological damage. We report the diagnosis of GS2 in a 4-year-old child with haemophagocytic syndrome, immunodeficiency, and secondary neurological disorders. Typical melanosome accumulation was found in skin melanocytes and pigment clumps were observed in hair shafts. Two heterozygous mutant alleles of the RAB27A gene were found, a C-T transition (C352T) that leads to Q118stop and a G-C transversion on the exon 5 splicing donor site (G467+1C). Functional assays showed increased cellular activation and decreased cytotoxic activity of NK and CD8+ T cells, associated with defective lytic granules release. Myosin-Va expression and localization in the patient lymphocytes were also analyzed. Most importantly, we show that cytotoxic activity of the patient's CD8+ T lymphocytes can be rescued in vitro by RAB27A gene transfer mediated by a recombinant retroviral vector, a first step towards a potential treatment of the acute phase of GS2 by RAB27A transduced lymphocytes.
Bizario
João C S
JC
Departamentos de Biologia Celular, Molecular e Bioagentes Patogênicos, Av. Bandeirantes 3900, 14049-900 Ribeirão Preto-São Paulo, Brazil.
Feldmann
Jérôme
J
Castro
Fabíola A
FA
Ménasché
Gaël
G
Jacob
Cristina M A
CM
Cristofani
L
L
Casella
Erasmo B
EB
Voltarelli
Júlio C
JC
de Saint-Basile
Geneviève
G
Espreafico
Enilza M
EM
D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000175:diagnosis / Q000235:genetics* / Q000628:therapy*; D007694:Killer Cells, Natural / Q000276:immunology; D008297:Male; D009154:Mutation; D009422:Nervous System Diseases; D010375:Pedigree; D016116:Piebaldism / Q000235:genetics / Q000628:therapy; D012190:Retroviridae / Q000235:genetics; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects* / Q000473:pathology; D016896:Treatment Outcome; D020691:rab GTP-Binding Proteins / Q000008:administration & dosage* / Q000235:genetics; D000075745:rab27 GTP-Binding Proteins
D000075745:rab27 GTP-Binding Proteins; C066694:RAB27A protein, human; D020691:rab GTP-Binding Proteins