Evaluation of genotype-phenotype relationships in patients referred for endocrine assessment in suspected Pendred syndrome.
METHODS
Patients with Pendred syndrome have genotypic and phenotypic variability, leading to challenges in definitive diagnosis. Deaf children with enlarged vestibular aqueducts are often subjected to repeated investigations when tests for mutations in SLC26A4 are abnormal. This study provides genotype and phenotype information from patients with suspected Pendred syndrome referred to a single clinical endocrinology unit.


METHODS
A retrospective analysis of 50 patients with suspected Pendred syndrome to investigate the correlation between genetic, perchlorate discharge test (PDT) and endocrine status.


RESULTS
Eight patients with monoallelic SLC26A4 mutations had normal PDT. Of the 33 patients with biallelic mutations, ten of 12 patients with >30% discharge developed hypothyroidism. In our cohort, c.626G>T and c.3-2A>G result in milder clinical presentations with lower median perchlorate discharge of 9.3% (interquartile range 4-15%) compared with 40% (interquartile range 21-60%) for the remaining mutations. Eight novel mutations were detected. All patients with PDT <30% remained euthyroid to date, although the majority are still under the age of 30. There was a significant correlation between PDT and goitre size (R=0.61, P=0.0009) and the age of onset of hypothyroidism (R=-0.62, P=0.0297). In our population, the hazard of becoming hypothyroid increased by 7% per percentage point increase in PDT (P<0.001).


CONCLUSIONS
There is a correlation between SLC26A4 genotype and thyroid phenotype. If results hold true for larger patient numbers and longer follow-up, then for patients with monoallelic mutations, PDT could be unnecessary. Patients with biallelic mutations and PDT discharge >30% have a high risk of developing goitre and hypothyroidism, and should have lifelong monitoring.
Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
Lip Min
LM
Soh
Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK m.r.druce@qmul.ac.uk.
Maralyn
M
Druce
Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
Ashley B
AB
Grossman
Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
Ann-Marie
AM
Differ
Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
Liala
L
Rajput
Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
Maria
M
Bitner-Glindzicz
Department of EndocrinologyBarts and the London School of Medicine and Dentistry, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UKOxford Centre for DiabetesEndocrinology and Metabolism, University of Oxford, Oxford, UKNorth East Thames Regional Genetics Service LaboratoryDepartment of Audiovestibular MedicineGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UKClinical and Molecular Genetics UnitUCL Institute of Child Health, London WC1N 1EH, UKClinical Genetics UnitGreat Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
Márta
M
Korbonits
D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003940:Diagnostic Techniques, Endocrine; D005260:Female; D005838:Genotype; D006044:Goiter, Nodular / Q000097:blood / Q000175:diagnosis* / Q000235:genetics*; D006319:Hearing Loss, Sensorineural / Q000097:blood / Q000175:diagnosis* / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012017:Referral and Consultation; D012189:Retrospective Studies; D055815:Young Adult