Seventy-one (71) children and adolescents, with a mean age of 11.3 ± 0.3 years (range 4.5-17.8), diagnosed with AT (antibodies against thyroid peroxidase [anti-TPO] and/or thyroglobulin [anti-Tg] ≥60 IU/mL, euthyroidism or treated hypothyroidism and goitre in thyroid gland ultrasonography) were randomized to receive 200 μg l-selenomethionine or placebo daily for 6 months.
Thyroid gland enlargement (goiter) appears to be primarily dependent on the presence of two mutant alleles of SLC26A4 in pediatric patients, but not in older patients.
Loss of function mutations in pendrin protein cause Pendred syndrome, a disorder characterized by sensorineural deafness and a partial iodide organification defect that may lead to thyroid goiter.
Deleterious mutations of SLC26A4 cause Pendred syndrome (PS), an autosomal recessive disorder comprising goitre and deafness with enlarged vestibular aqueducts (EVA), and nonsyndromic hearing loss (NSHL).
Pendred syndrome, a combination of sensorineural deafness, impaired organification of iodide in the thyroid and goitre, results from biallelic defects in pendrin (encoded by SLC26A4), which transports chloride and iodide in the inner ear and thyroid respectively.
Considering the presence of SLC26A4 mutations and thyroid function, we could identify three sub-groups of patients: group 1, non syndromic EVA (ns EVA, no SLC26A4 mutation and no thyroid dysfunction); group 2, EVA with DFNB4 (single SLC26A4 gene mutation and no thyroid dysfunction); group 3, EVA with Pendred Syndrome (two pathological mutation of SLC26A4 and thyromegaly with thyroid dysfunction).
The present results question the sensitivity of the perchlorate test for the diagnosis of Pendred syndrome and support the use of a molecular analysis of the PDS gene in the assessment of individuals with severe to profound congenital hearing loss associated with inner ear morphological anomaly even in the absence of a thyroid goiter.
The main outcomes were TPOAb concentrations and positivity, thyroid hormone concentrations (TSH, free T4), and clinical thyroid diseases (subclinical and overt hypothyroidism and goiter).
15.5% (11/71) were hypothyroid, 17 (23.9%) were positive for thyroid peroxidase (TPO) and/or thyroglobulin (Tg) antibodies, and 24 (33.8%) had thyromegaly.
The first one is named Pendred Syndrome (PS) when deafness is associated with thyroid goiter; the second is called DFNB4, when no other symptoms are present.
Pendred syndrome is an autosomal recessive disorder characterized by hearing loss and goiter and is caused by bi-allelic mutations (homozygous or compound heterozygous) of the PDS (SLC26A4) gene.
All patients harbouring mutations in the SLC26A4 gene had goiter and a positive perchlorate discharge test: 3 were slightly hypothyroid and 2 euthyroid.
Two compound heterozygous mutations (c.215delA/c.2422T-->C and c.387delC/c.1159G-->A) in the thyroid peroxidase gene responsible for congenital goitre and iodide organification defect.
The PDS gene (7q31), responsible for Pendred syndrome (congenital sensorineural hearing loss and goiter), encodes a transmembrane protein known as pendrin.
It has been shown that mutations in the SLC26A4 gene are involved in syndromic deafness characterized by congenital sensorineural hearing impairment and goitre (Pendred's syndrome), as well as in congenital isolated deafness (DFNB4), both of which are associated with enlarged vestibular aqueduct (EVA).
Clinical characteristics of patients with SLC26A4 mutations were congenital, fluctuating and progressive hearing loss usually associated with vertigo and/or goiter.
Phenocopies for deafness and goiter development in a large inbred Brazilian kindred with Pendred's syndrome associated with a novel mutation in the PDS gene.