Gangliosides are a group of sphingolipids that are found especially in the presynaptic membranes of neuromuscular synapses
(2). They are found as simple structures named GM3, GD3, GT3 and complex structures named a-, b-, c-, etc. There can be different ganglioside types in different regions of the nervous system and gangliosides of different structure in the different parts of neurons. Studies have demonstrated that the GM1, GD1, GT1b, GT1a and GQ1b forms that have an alpha isomeric structure are located in cholinergic nerve ends while motor nerve ends mostly have the GQ1b, GM1, GD1a, GD1b, GT1a and GD3 types
(13) .
The functions of gangliosides have not been fully explained but the latest research shows that they play a role in cell-cell interaction, regulation of membrane protein functions, neuronal development, neuronal Ca+ balance, axonal growth and synaptic conduction(4,8,17). Ganglioside-related disorders appear due to ganglioside synthesis or metabolism and the development of anti-ganglioside antibodies. GBS is in the second group and is one of the disorders where anti-ganglioside antibodies have been best studied. Anti-ganglioside antibodies are found in approximately half of GBS cases and 90% of MFS cases and the serum antibody titer is reported to be high in the acute stage, decreasing with clinical recovery(21). Other than the relationship between MFS and Anti GQ1b, none of the other GBS subtypes have been shown to develop due to a specific anti-ganglioside antibody. The GBS subtypes AMAN and AMSAN seem to go together with GM1, GM1b, GD1a or GalNAc-GD1a antibodies. However, anti-ganglioside antibodies that have developed against an antigen can frequently show cross-reaction with other gangliosides. Another recent study has reported that the anti-ganglioside antibodies in GBS bind more to specific ganglioside complexes than a single molecule(12).
GBS appears with acute or subacute symmetrical paralysis, areflexia and sensory disturbances and two thirds of the cases have autonomic dysfunction(9). The autonomic dysfunction findings may be sympathetic or parasympathetic hyperactivity or deficiency(6). The clinical findings of AHS that develop as a dilated pupil and hypoactivity of the deep tendon reflexes as a result of a parasympathetic problem are similar to those of GBS and MFS. There are some case reports on the presence of internal ophthalmoplegia in GBS and approximately half of MFS cases are reported to suffer from pupillary problems and mydriasis(14,18). We found anti-ganglioside antibodies in 3 of 10 patients while this test was negative in all control group subjects. Three of our patients were old AHS cases that were included in the study after previous records were reviewed and serum anti-ganglioside antibodies were found to be negative in these patients although the condition continued. Of the remaining 6 patients, we found GD1b, GT1b, GM3 antibodies to be positive in 2 and only GM3 antibodies to be positive in 1 patient. The negative anti-ganglioside antibody in the old AHS cases included in the study may have been affected by the test being performed at the late stage of the disorder.
Our results demonstrate that anti-ganglioside antibodies may play a role in AHS development. Studies with a larger number of patients to investigate anti-ganglioside antibodies in acute-stage AHS cases and also other studies on immune treatment in AHS are necessary to clarify this matter.
Received by: 09 August 2011
Revised by: 04 March 2012
Accepted: 23 March 2012
