A novel heterozygous deletion frameshift mutation of GATA3 in a Japanese kindred with the hypoparathyroidism, deafness and renal dysplasia syndrome

A Novel De Novo GATA Binding Protein 3 Mutation in a Turkish Boy with Hypoparathyroidism, Deafness, and Renal Dysplasia Syndrome

Hypoparathyroidism, deafness, and renal dysplasia (HDR; OMIM 146255) syndrome is a rare disease, inherited dominantly and found to be related with GATA3 (GATA binding protein 3) gene mutations. A 13-year and 8-month-old boy who presented with hypocalcemia was diagnosed with hypoparathyroidism. He also had dysmorphic facial features, renal anomaly (pelvic kidney), and mild sensorineural hearing loss. His cranial computed tomography revealed multiple calcifications in bilateral centrum semiovale, corona radiata, and basal ganglions suggesting a persistent hypoparathyroidism. Thus, the presence of triad of HDR syndrome was considered, and genetic analysis using a next-generation sequencer identified a novel de novo missense mutation in exon 4 p.R276Q (c.827G>A) of GATA3 gene. This is the second patient who was reported to have a mutation in GATA3 gene from Turkey. In conclusion, although HDR syndrome is a rare condition, it should be kept in mind in patients with hypoparathyroidism. Classical triad can easily be identified if patients diagnosed with hypoparathyroidism are also evaluated with a urinary tract ultrasound and an audiometer.

Identification of a novel GATA3 mutation in a deaf Taiwanese family by massively parallel sequencing

Recent studies have confirmed the utility of massively parallel sequencing (MPS) in addressing genetically heterogeneous hereditary hearing impairment. By applying a MPS diagnostic panel targeting 129 known deafness genes, we identified a novel frameshift GATA3 mutation, c.149delT (p.Phe51LeufsX144), in a hearing-impaired family compatible with autosomal dominant inheritance. The GATA3 haploinsufficiency is thought to be associated with the hypoparathyroidism, sensorineural deafness, and renal dysplasia (HDR) syndrome. The pathogenicity of GATA3 c.149delT was supported by its absence in the 5400 NHLBI exomes, 1000 Genomes, and the 100 normal hearing controls of the present study; the co-segregation of c.149delT heterozygosity with hearing impairment in 9 affected members of the family; as well as the nonsense-mediated mRNA decay of the mutant allele in in vitro functional studies. The phenotypes in this family appeared relatively mild, as most affected members presented no signs of hypoparathyroidism or renal abnormalities, including the proband. To our knowledge, this is the first report of genetic diagnosis of HDR syndrome before the clinical diagnosis. Genetic examination for multiple deafness genes with MPS might be helpful in identifying certain types of syndromic hearing loss such as HDR syndrome, contributing to earlier diagnosis and treatment of the affected individuals.

Renal phenotypic variability in HDR syndrome: glomerular nephropathy as a novel finding

HDR syndrome (hypoparathyroidism, sensorineural deafness, renal abnormalities) (OMIM #146265) is a rare autosomal dominant disorder caused by mutations in the GATA-3 gene (OMIM 13120), a transcription factor coding for a protein involved in vertebrate embryonic development. More than a hundred cases with variable renal features have been described so far. Here, we report on a patient suffering from HDR syndrome with glomerular nephropathy. Hypoparathyroidism appeared early in childhood but the subsequent features of HDR occurred later in the form of bilateral sensorineural deafness and renal insufficiency associated with nephrocalcinosis. HDR was not initially diagnosed due to the appearance of a transitory cardiac involvement and atypical renal symptoms (diffuse proliferative glomerulonephritis characterized by a self-limiting nephrotic syndrome).

CONCLUSION

HDR syndrome with glomerular nephropathy has not yet been reported to our knowledge. Further studies of GATA-3 are needed to explore the involvement of this transcription factor in the development of HDR in humans, particularly in the kidneys.

Novel dominant-negative mutant of GATA3 in HDR syndrome

HDR syndrome is an autosomal dominant disorder characterized by hypoparathyroidism, sensorineural deafness, and renal anomaly caused by mutation of the GATA3 gene located at chromosome 10p15. We report the case of a neonate with HDR syndrome and a novel GATA3 mutation. We performed genetic and functional analysis of GATA3 in this patient and identified a novel heterozygous 1516G> C missense mutation in exon 5, resulting in a cysteine-to-serine substitution at codon 321 (Cys321Ser). Mutated and wild-type GATA3 proteins were expressed at a similar level in vitro, indicating that the mutated GATA3 protein was stable. Luciferase assay revealed that the Cys321Ser-mutated GATA3 lacked transactivation activity due to loss of DNA-binding activity as confirmed by gel shift assay. Moreover, mutated GATA3 exerted a dominant-negative effect over the transactivation activity of wild-type GATA3. These findings indicate that not only haploinsufficiency of GATA3 but also the dominant-negative effect of Cys321Ser-mutated GATA3 might have been responsible for the HDR syndrome phenotype of our patient.

HDR syndrome: a novel "de novo" mutation in GATA3 gene

Human GATA3 haploinsufficiency leads to HDR (hypoparathyroidism, deafness, and renal dysplasia) syndrome. The development of a specific subset of organs in which this transcription factor is expressed appears exquisitely sensitive to gene dosage. We report on a 14-year-old patient with symptomatic hypoparathyroidism, sensorineural bilateral deafness, unilateral renal dysplasia, bilateral palpebral ptosis, and horizontal nystagmus. Fundoscopy displayed symmetrical pseudopapilledema, and brain CT scan revealed basal ganglia calcifications. FISH analysis did not disclose any microdeletion in the 22q11.2 or 10p14 regions. GATA3 mutation analysis identified a heterozygous deletion of GG nucleotides at codon 36 and 37 (c.108_109delGG) in exon 2 causing a frameshift with a premature stop codon after a new 15-aminoacid sequence. Restriction endonuclease analysis performed in parents was negative. Our patient carries a novel "de novo" GATA3 mutation, providing further evidence that HDR syndrome is caused by haploinsufficiency of GATA3, which may be responsible for a complex neurologic picture besides the known triad.