Detection of duplication of PMP22 gene by fluorescent in situ hybridization (fish) in Charcot Marie tooth type 1 in public hospital of south of Chile

Abstract

The genotypic diagnosis in CMT is a public health need. In our country, a genetic study is carried out in a single laboratory (INTA) with restricting of access to public patients. To determine presence of duplication of the PMP22 gene in patients with CMT1 by FISH of the Neurology Unit of the Hospital Regional de Concepcion. CMT1 it is produced by a duplication of 1.5mb on chromosome 17p11.2detectable by FISH and correlated with "classic" phenotype (onset development of symptoms in the first 2 decades, slow and progressive course, characteristic orthopedically alterations and decrease in the speed of nerve conduction of arms 16 patients are included M38% F62% with average age 38(16–63), clinically grouped i 4 CLASSIC PENOTHYPE OF CMT1, 7 other HEREDITARY NEUROPATHIES and 5 DEMYELINATING NEUROPATHIES ACQUIRED In FISH assay, presence of more than 40% nuclei with 3 signals of the PMP22 gene and 2 corresponding to the centromere of chromosome 17 was considered positive. We found 4 positive cases, 3 in CMT1 group and 1 in OTHER HEREDITARY NEUROPATHIES (case of Hereditary neuropathy with Liability to pressure palsies and none in DEMYELINATING NEUROPATHIES ACQUIRED Three counter samples (1Positive/2Negative) were analyzed in INTA using MLPA and FISH having concordance in everyone case. Technique of FISH is reliable in the detection of the duplication responsible for CMT1 and increasing the number of cases it is feasible to validate the method in our place and implement this genetic diagnosis in our public care system.