Sporadic congenital nonautoimmune hyperthyroidism caused by P639S mutation in thyrotropin receptor gene

• Published in: European journal of pediatrics Vol. 171; no. 7; pp. 1133 - 1137
• Main Authors: Agretti, Patrizia, De Marco, Giuseppina, Biagioni, Martina, Iannilli, Antonio, Marigliano, Marco, Pinchera, Aldo, Vitti, Paolo, Cherubini, Valentino, Tonacchera, Massimo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-07-2012; Springer; Springer Nature B.V
• Subjects: Age; Antibodies; Bioassays; Biological and medical sciences; Case Report; Case reports; Child, Preschool; Congenital diseases; Diarrhea; Disease; Endocrinopathies; Female; General aspects; Genetic Markers; Growth Disorders - etiology; Humans; Hyperthyroidism; Hyperthyroidism - complications; Hyperthyroidism - congenital; Hyperthyroidism - diagnosis; Hyperthyroidism - genetics; Medical sciences; Medicine; Medicine & Public Health; Mutation; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Parents & parenting; Patients; Pediatrics; Point Mutation; Polymerase chain reaction; Receptors, Thyrotropin - genetics; Thyroid gland; Thyroid. Thyroid axis (diseases); Ultrasonic imaging; Velocity; Italy; Germline mutation; Sporadic congenital nonautoimmune hyperthyroidism; Thyrotropin receptor; Genetic analysis; Thyrotoxicosis; Endocrinopathy; Pediatrics; Congenital; Sporadic; Hyperthyroidism; Thyroid diseases; TSH receptor; Congenital disease; Gene; Analysis; Germ line; Genetics; Mutation
• ISSN: 0340-6199; 1432-1076
• DOI: 10.1007/s00431-012-1702-z

Germline mutations of thyrotropin receptor (
TSHR
) gene determining a constitutive activation of the receptor were identified as a molecular cause of familial or sporadic congenital nonautoimmune hyperthyroidism (OMIM: 609152) (Nat Genet 7:396–401,
1994
; N Engl J Med 332:150–154,
1995
; Acta Endocrinol (Copenh) 100:512–518,
1982
). We report the case of an Italian child subjected to the first clinical investigation at 24 months for an increased growth velocity; biochemical investigation showed high FT4 and FT3 serum values and undetectable thyrotropin in the absence of anti-thyroid antibodies; the thyroid gland was normal at ultrasound examination. Treatment with methimazole was started at the age of 30 months when her growth velocity was high and the bone age was advanced. DNA was extracted from her parents’, brother’s, and the patient’s blood. Exons 9 and 10 of the
TSHR
gene were amplified by polymerase chain reaction and subjected to direct sequencing. In proband, a heterozygous substitution of cytosine to thymine determining a proline to serine change at position 639 (P639S) of the
TSHR
was detected while the parents and brothers of the propositus, all euthyroid, showed only the wild-type sequence of the
TSHR
gene. This mutation was previously described as somatic in patients affected by hyperfunctioning thyroid nodules and as germline in a single Chinese family affected by thyrotoxicosis and mitral valve prolapse. This constitutively activating mutation is able to activate both the cyclic AMP and the inositol phosphate metabolic pathways when expressed in a heterologous system. In conclusion, we describe the first case of sporadic congenital nonautoimmune hyperthyroidism caused by de novo germinal P639S mutation of
TSHR
.