Glutamic acid decarboxylase autoantibodies in Sudanese diabetic children and their siblings

Abstract

Background: Type -1 diabetes mellitus(T1DM)is known to be an autoimmune disease . Glutamic acid
decarboxylase (GAD) is the enzyme responsible for the conversion of glutamic acid into the inhibitory
neurotransmitter gamma amino butyric acid (GABA).GAD is a major auto antigen in type 1 diabetes ,being
recognized by auto antibodies present in sera of the majority of patients at onset of the disease . It is also one
of the important predictive immunological markers in developing the disease among first degree relatives.
Objectives: (a) To determine the prevalence of anti- GAD antibodies in Sudanese diabetic children ,
their healthy younger siblings and the control group. (b) To evaluate the presence of GAD antibodiesas an
indicator of autoimmunity in T1DM in Sudanese diabetic Children .
Methods: This is a hospital- based, prospective, case- controlled study.The patients were randomly
selected from diabetic children attending two hospitals in Khartoum State .Sixty –five diabetic children , 25
of their healthy siblings and 31 healthy controls were enrolled . A precoded questionnaire was completed .
The presence of GAD antibodies was investigated for the study subjects,their siblings and control subjects
using Diamyd Anti GAD65 Radioimmunoassay.
Results: The majority of diabetic patients were between 11 – 15 years representing 37(57.1%). Antibodies
to glutamic acid decarboxylase { considered by the lab to be positive if >10.2 U/ml } .GAD antibodies
were found to be significantly positive in 30 (46.1%) of the diabetic children compared to only one (3.2
%) of the controls , P- value was highly significant { P < 0.0001 } . Highest titers were detected in diabetics
with disease duration over one year . GAD antibodies were tested in 25 of siblings.Significant titers were
detected in only 2 of them representing 8% .
Conclusions: It was concluded that GAD antibodies is an important immunological marker in Sudanese
children with IDDM and similar to Asian and European populations , However, further research using other
tests like antibodies against insulin(IAA) , islet cells (ICA) and zink transporter 8 (ZnT8Ab) as well as
insulinoma- associated -2 autoantibodies (IA-2A) would be more specific .The role of GAD in disease
prediction among siblings needs further research