in the Ski complex and clinically they are indistinguishable from each other. Inherited in an autosomal recessive manner with complete penetrance, approximately 2/3rd of patients are homozygotes and 1/3rd are compound heterozygous. Mutations are spread throughout the gene with no identifiable hotspot and generally consist of frameshift, missense and nonsense mutations; a smaller number are splice site mutations. There is no clear genotype/phenotype correlation with overall disease severity, even siblings with the same homozygous mutation display variable phenotypes. Patients have been described globally in Europe, Saudi Arabia, Malaysia, China and Japan. Intractable watery diarrhoea is a near consistent feature in almost all described cases, almost always starting soon after birth and commonly requiring parenteral nutrition. In cases which do not require parenteral nutrition an elemental diet and supplemental feeding is required. The majority of SKIV2L pathogenic variant harbouring patients are small at birth (<10th centile) and remain growth restricted despite increased nutrition. Hair abnormalities are seen in >90% of patients and are described as woolly, brittle hair that is easily removed. Facial dysmorphisms are found in most patients and become more apparent with age. These include a large forehead, broad base of the nose and hypertelorism. Overall the facial features are described as “coarse”. Liver disease is reported frequently in SKIV2L patients (>80%), ranging from fibrosis, cirrhosis, hepatomegaly and raised liver enzymes. Histopathology when performed shows iron overload and can be consistent with haemochromatosis. Skin abnormalities are frequently reported and are variable including café au lait lesions, haemangiomas and xerosis. A report from Saudi Arabia suggested the skin changes were more frequent in the lower limb and pelvic region of their regional cohort. Immunodeficiency is reported in some patients. It is poorly delineated and mainly consists of low immunoglobulins and inadequate vaccine responses, however hyper IgA has also been reported. Immunoglobulin therapy has been shown to lower rates of infection. Less commonly congenital cardiac defects have been reported, mostly ventricular septal defects (VSD), atrial septal defects (ASD), and rarely Tetralogy of Fallot and peripheral pulmonary stenosis. Mortality rate Initially reported as high as 62.5% with most deaths in the first year, more recent reports have estimated mortality of around 30%, which is similar to other disorders which are dependent on parenteral nutrition. Recommended treatment and surveillance No specific treatments are available for THES. The goal is to maximise weight gain and reduce infection rates. Most children require parenteral nutrition (PN)