RESUMO
Charcot- Marie- Tooth (CMT) disease includes a group of clinically and genetically heterogeneous neuropathic disorders with an estimated frequency of 1 on 2.500 individuals. CMTs are differently classified according to the age of onset, type of inheritance, and type of inheritance plus clinical features. For these disorders, more than 100 genes have been implicated as causal factors, with mutations in the PMP22 being one of the most common. The demyelinating type (CMT1) affects more than 30% of the CMTs patients and manifests with motor and sensory dysfunctions of the peripheral nervous system mainly starting with slow progressive weakness of the lower extremities. We report here a 12 year- old boy presenting with typical features of CMT1 type, hearing impairment, and inguinal hernia who at the next-generation sequence analysis displayed a concomitant presence of two variants: the c.233 C>T p.Ser 78Leu of the MPZ gene (NM_000530.6) characterized as pathogenetic and the c.1403 G>A p.Arg 468His of the MFN2 gene (NM_014874.3) characterized as VUS. Concomitant variant mutations in CMTs have been uncommonly reported. The role of these gene mutations on the clinical expression and a literature review on this topic is discussed.
RESUMO
TL antigens are class I glycoproteins which are expressed on thymocytes and which are coded by the Tla region of the major histocompatibility complex of the mouse. Biochemical analysis of TL molecules from different strains of mice revealed structural variation determined by the Tla region which is detectable by peptide mapping, isoelectric focusing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two-dimensional gels, and by differential reactivity of allelic forms of TL molecules with a panel of anti-TL reagents. The quantity of TL expressed on thymocytes is also influenced by the Tla region; three quantitative phenotypes were identified: high (Tlaa, Tlad, Tlae), intermediate (Tlac, Tlaf), and low (Tlab). (Relative amounts: 1000: 100: 1.) Some thymic leukemias arising in (Tlab, Tlac) mice with genetically determined reduced levels of thymic TL were found to express TL molecules which were structurally indistinguishable from TL isolated from thymocytes but were present in larger amounts. This suggests that TL structural genes are intrinsically capable of full expression in all mice but that the Tla region of mice expressing an intermediate or low quantity of TL is marked by some feature which causes the thymocyte to express less than the full amount of TL possible.
