Endocrine Abstracts

JOINT2005

Monocarboxylate transporter 8 (MCT8) deficiency known as Allan-Hernon-Dudley syndrome is an X-linked disorder caused by an impairment of the transcellular transportation of thyroid hormones into neurons due to SLC16A2 gene mutations. Clinical symptoms are a consequence of developing hypothyroidism in the brain and signs of hyperthyroidism in peripheral tissues. Affected patients develop mental retardation, axial hypotonia, peripheral spasticity, involuntary movements that may be paroxysmal. New treatments are being applied. We report a patient, who was born from an uneventful pregnancy in the 37th week of gestation, Apgar score 8/9, eutrophic. Shortly after birth suffered from pneumothorax, which was drained, he was dismissed with slight proximal and axial hypotonia. Neurological follow up showed deterioration of axial muscle tone around 5 months, but till 8 months there was evident regression in psychomotor development, pronounced hypotonia. EMG and EEG showed no pathology. SMA screen was negative. At 13 months MRI: delayed white matter myelinisation. EEG: unspecific abnormal activity. Endocrine assessment at 8 months was appropriate, but at 13 months showed signs of primary hypothyroidism and Thyroxin was started. After 5 months on medication there was no change. At 23 months NGS revealed mutation in SLC16A2 gene (c.940C T (p.Arg314Ter): Allan-Herndon-Dudley syndrome i.e. MCT8 deficiency. Endocrine tests on Thyroxin were broadened to fT3 and showed TSH 2,7 mIU/l, fT4 11 pmol/l fT3 8,35 pmol/l (2,5 – 5,8), Thyroxin was stopped. Vomiting led to elimination diet, which helped but he didn´t gain weight, while growing normally. At 32 months TSH: 4,52 mU/l [0,70\.5,97], Ft4: 6,61 pmol/l [10,45\.22,35], fT3 14,72 pmol/l [3,69\.8,46], with pronounced clinical picture. We started treatment with Tiratricol 350 ug daily, increasing the dose during 6 weeks to 75mg/kg daily, when the boy started to gain weight, slightly improved the axial muscle tone. But in another 8 weeks, he started vomit, was constipated, lost weight. At this time TSH was supressed. The dose was lowered and has been kept till now with normalised fT3. Evidence of epileptic encephalopathy on EEG and seizures led to antiepileptic treatment with good response. He is improving now his psychomotor development, slowly gaining weight on 5O mg/kg of Tiratricol.