We describe the case of a previously fit child with recurrent vomiting, faltering growth, persistent diarrhoea and rashes who was diagnosed with a sodium-dependent multivitamin transporter (SMVT) defect. Whole exome sequencing revealed he was homozygous for aSLC5A6missense variant. TheSLC5A6gene produces SMVTs, which are expressed in various tissues including the intestine, brain, liver, lung, kidney, cornea, retina and heart. It plays a major role in the uptake of biotin, pantothenate and lipoate in the digestive system and transporting B-group vitamins across the blood–brain barrier.This case was only the fourth described in literature. Management was with vitamin replacement therapy: biotin, dexpanthenol and α-lipoic acid. With treatment there was significant, sustained clinical improvement with resolution of recurrent vomiting, rashes and graduation to full enteral feeds.This case highlights how defects in multivitamin transporters can lead to multisystemic disease and subsequent targeted treatment leading to significant clinical improvement.
Background
Coeliac disease (CD) is an immune mediated systemic disorder elicited by the ingestion of gluten and related prolamines in genetically susceptible individuals. Diagnosis has been based on small bowel histology as per ESPGHAN guidelines. In 2012 ESPGHAN guidelines1 were modified and recommend that in symptomatic patients a diagnosis of CD can be made without small-bowel biopsy if anti-tissue transglutaminase antibody (TTG) titre is greater than 10 times upper limit of normal (>10ULN), together with presence of HLA-DQ2 and/or DQ8. This study aimed to examine the relationship between TTG levels and the corresponding histological features.
Methods
Data was collected prospectively at diagnosis of CD from 126 consecutive children between June’ 2011 – May’ 2012. TTG was measured using ELISA technique. Histological samples were obtained from endoscopic small-bowel biopsies and interpreted by paediatric histopathologists. The relationship between the modified Marsh criteria histological findings and contemporaneous TTG levels was analysed.
Results
Out of 126 children, 13(10.5%) had positive TTG but no documented titres. In 12(10%) histological report did not specify Marsh classification. Complete data of histological report and TTG level were therefore available from 104 children (82%). The data (table) shows an association between TTG level and histological staging of CD. 58 (48%) children had TTG >10ULN (>100U/ml). 57/58 of these patients had biopsy proven CD. The sensitivity of the TTG level >100U/ml alone in correctly diagnosing CD in this cohort was 98.3%.
Modified Marsh Criteria identified on histology
3a
3b
3c
Mean TTG level (U/ml) (SD)
95.9
110.0
167.4
(95% confidence level)
66.8–124.9
87.5–132.3
143.0–191.7
Conclusion
98.3% of children with TTG >100U/ml had histologically confirmed CD although total villous atrophy was associated more often with TTG level of >200U/ml. It is essential to report TTG titres by all laboratories. This study supports the new ESPGHAN guidelines for the selective use of high TTG levels in diagnosing CD in symptomatic children without a biopsy.
Reference
Husby S, et al. J Pediatr Gastroenterol Nutr. 2012;54(1):136–60
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