Trichohepatoenteric Syndrome

Clinical characteristics: Trichohepatoenteric syndrome (THES), generally considered to be a neonatal enteropathy, is characterized by intractable diarrhea (seen in almost all affected children), woolly hair (seen in all), intrauterine growth restriction, facial dysmorphism, and short stature. Additional findings include poorly characterized immunodeficiency, recurrent infections, skin abnormalities, and liver disease. Mild intellectual disability (ID) is seen in about 50% of affected individuals. Less common findings include congenital heart defects and platelet anomalies. To date 52 affected individuals have been reported.

Diagnosis/testing: The diagnosis of THES is established in a proband with biallelic pathogenic variants in either SKIC3 (formerly TTC37) or SKIC2 (formerly SKIV2L).

Management: Treatment of manifestations: To promote maximal weight gain and linear growth, most children initially require parenteral nutrition (PN). As tolerated, oral feeding (typically a semi-elemental diet) can be combined with PN. On the rare occasion that PN is unnecessary, anecdotal reports describe use of mainly an amino acid-based formula. To reduce the burden of infections, immunoglobulins can be supplemented in those with low immunoglobulin levels or immunoglobulin functional abnormalities. Individual management of ID is based on age-appropriate assessments of cognitive development, speech and language development, and psychosocial skills.

Surveillance: For children not receiving PN: close monitoring of nutritional status by a pediatric nutritionist to assure prompt intervention as needed. Yearly assessment of: diarrhea for changes that could suggest inflammatory bowel disease; liver function and size; immunoglobulin serum concentration and functionality; TSH level for evidence of hypothyroidism. Periodic assessment of: cognitive development, speech and language, and psychosocial skills for evidence of ID.

Genetic counseling: THES is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Once the SKIC2 or SKIC3 pathogenic variants have been identified in an affected family member, carrier testing of at-risk relatives, prenatal testing for a pregnancy at increased risk, and preimplantation genetic testing are possible.