ABSTRACT
CONTEXT: Congenital isolated TSH deficiency (i-TSHD) is a rare form of congenital hypothyroidism. Five genes (IGSF1, IRS4, TBL1X, TRHR, and TSHB) responsible for the disease have been identified, although their relative frequencies and hypothalamic/pituitary unit phenotypes have remained to be clarified. OBJECTIVES: To define the relative frequencies and hypothalamic/pituitary unit phenotypes of congenital i-TSHD resulting from single gene mutations. PATIENTS AND METHODS: Thirteen Japanese patients (11 boys and 2 girls) with congenital i-TSHD were enrolled. IGSF1, IRS4, TBL1X, TRHR, and TSHB were sequenced. For a TBL1X mutation (p.Asn382del), its pathogenicity was verified in vitro. For a literature review, published clinical data derived from 74 patients with congenital i-TSHD resulting from single-gene mutations were retrieved and analyzed. RESULTS: Genetic screening of the 13 study subjects revealed six mutation-carrying patients (46%), including five hemizygous IGSF1 mutation carriers and one hemizygous TBL1X mutation carrier. Among the six mutation carriers, one had intellectual disability and the other one had obesity, but the remaining four did not show nonendocrine phenotypes. Loss of function of the TBL1X mutation (p.Asn382del) was confirmed in vitro. The literature review demonstrated etiology-specific relationship between serum prolactin (PRL) levels and TRH-stimulated TSH levels with some degree of overlap. CONCLUSIONS: The mutation screening study covering the five causative genes of congenital i-TSHD was performed, showing that the IGSF1 defect was the leading genetic cause of the disease. Assessing relationships between serum PRL levels and TRH-stimulated TSH levels would contribute to predict the etiologies of congenital i-TSHD.
Subject(s)
Congenital Hypothyroidism/genetics , Congenital Hypothyroidism/pathology , Immunoglobulins/genetics , Mass Screening/methods , Membrane Proteins/genetics , Mutation , Thyrotropin/deficiency , Adolescent , Adult , Biomarkers/analysis , Child , Child, Preschool , DNA Mutational Analysis/methods , Female , Follow-Up Studies , Humans , Infant , Infant, Newborn , Insulin Receptor Substrate Proteins/genetics , Male , Pedigree , Prognosis , Receptors, Thyrotropin-Releasing Hormone/genetics , Thyrotropin/blood , Thyrotropin/genetics , Transducin/genetics , Young AdultABSTRACT
The HNF4A p.R76W mutation causes congenital hyperinsulinism with Fanconi syndrome. Here, we report two cases who also presented with increased urinary calcium excretion and one had a transient hepatic dysfunction with hepatomegaly. Clinical variations including transient liver dysfunction is a likely mutation-specific clinical characteristic.
