Functional assessment of allelic variants in the SLC26A4 gene involved in Pendred syndrome and nonsyndromic EVA.
Pendred syndrome is an autosomal recessive disorder characterized by sensorineural hearing loss, with malformations of the inner ear, ranging from enlarged vestibular aqueduct (EVA) to Mondini malformation, and deficient iodide organification in the thyroid gland. Nonsyndromic EVA (ns-EVA) is a separate type of sensorineural hearing loss showing normal thyroid function. Both Pendred syndrome and ns-EVA seem to be linked to the malfunction of pendrin (SLC26A4), a membrane transporter able to exchange anions between the cytosol and extracellular fluid. In the past, the pathogenicity of SLC26A4 missense mutations were assumed if the mutations fulfilled two criteria: low incidence of the mutation in the control population and substitution of evolutionary conserved amino acids. Here we show that these criteria are insufficient to make meaningful predictions about the effect of these SLC26A4 variants on the pendrin-induced ion transport. Furthermore, we functionally characterized 10 missense mutations within the SLC26A4 ORF, and consistently found that on the protein level, an addition or omission of a proline or a charged amino acid in the SLC26A4 sequence is detrimental to its function. These types of changes may be adequate for predicting SLC26A4 functionality in the absence of direct functional tests.
Pera
Alejandra
A
Unidad de Genética Molecular, Hospital Ramón y Cajal, Centro de Investigación Biomédica de Enfermedades Raras, ISCIII, 28034 Madrid, Spain.
Dossena
Silvia
S
Rodighiero
Simona
S
Gandía
Marta
M
Bottà
Guido
G
Meyer
Giuliano
G
Moreno
Felipe
F
Nofziger
Charity
C
Hernández-Chico
Concepción
C
Paulmichl
Markus
M
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D015331:Cohort Studies; D005808:Genes, Recessive; D005838:Genotype; D006319:Hearing Loss, Sensorineural / Q000235:genetics*; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames; D010641:Phenotype; D011110:Polymorphism, Genetic; D017386:Sequence Homology, Amino Acid; D000076988:Sulfate Transporters; D013577:Syndrome; D014723:Vestibular Aqueduct / Q000002:abnormalities*
D026901:Membrane Transport Proteins; C085609:SLC26A4 protein, human; D000076988:Sulfate Transporters