10p12.1 deletion: HDR phenotype without DGS2 features

Clinical report of a neonate carrying a large deletion in the 10p15.3p13 region and review of the literature

Background

Terminal deletion of chromosome 10p is a rare chromosomal abnormality. We report a neonatal case with a large deletion of 10p15.3p13 diagnosed early because of severe clinical manifestations.

Case presentation

Our patient presented with specific facial features, hypoparathyroidism, sen sorineural deafness, renal abnormalities, and developmental retardation, and carried a 12.6 Mb deletion in the 10p15.3 p13 region. The terminal 10p deletion involved in our patient is the second largest reported terminal deletion reported to date, and includes the ZMYND11 and GATA3 genes and a partial critical region of the DiGeorge syndrome 2 gene (DGS2).

Conclusion

On the basis of a literature review, this terminal 10p deletion in the present case is responsible for a specific contiguous gene syndrome. This rare case may help the understanding of the genotype–phenotype spectrum of terminal deletion of chromosome 10p.

Inherited glomerular diseases in the gilded age of genomic advancements

The synchronized advent of high-throughput next-generation sequencing technology and knowledge of the human genome has rendered exponential contributions to our understanding of the pathophysiology of glomerular kidney diseases. A genetic diagnosis can now be made or confirmed in about two-thirds of the suspected inherited glomerular diseases. Next-generation sequencing is adept at identifying single nucleotide variations and small insertions or deletions that constitute majority of the disease-causing mutations. Description of the complete mutation spectrum in syndromic glomerulopathies may require the use of both sequencing and cytogenetic methods to detect large structural DNA variation in addition to single nucleotide changes. The enthusiastic application of genetic and genomic knowledge to inherited glomerular diseases has uncovered anticipated and unforeseen challenges mainly related to the biological interpretation of variants of uncertain significance and the limited benefit on clinical management for the individual patient when a diagnosis is obtained. To attain the ultimate goal of transforming clinical decision-making based on accurate genetic diagnosis using genomic information, these challenges need to be addressed. Till then, the glory of genomic medicine stands the test of time in this gilded age of genomic advancements.

Genetics of vesicoureteral reflux and congenital anomalies of the kidney and urinary tract

The definition of congenital anomalies of the kidney and urinary tract (CAKUT) is the disease of structural malformations in the kidney and/or urinary tract containing vesicoureteral reflux (VUR). These anomalies can cause pediatric chronic kidney disease. However, the pathogenesis of CAKUT is not well understood, because identifying the genetic architecture of CAKUT is difficult due to the phenotypic heterogeneity and multifactorial genetic penetrance. We describe the current genetic basis and mechanisms of CAKUT including VUR via approaching the steps and signaling pathways of kidney developmental processes. We also focus on the newly developed strategies and challenges to fully address the role of the associated genes in the pathogenesis of the disease.

Genetics of Vesicoureteral Reflux

Vesicoureteral reflux (VUR) is the retrograde passage of urine from the bladder to the upper urinary tract. It is the most common congenital urological anomaly affecting 1-2% of children and 30-40% of patients with urinary tract infections. VUR is a major risk factor for pyelonephritic scarring and chronic renal failure in children. It is the result of a shortened intravesical ureter with an enlarged or malpositioned ureteric orifice. An ectopic embryonal ureteric budding development is implicated in the pathogenesis of VUR, which is a complex genetic developmental disorder. Many genes are involved in the ureteric budding formation and subsequently in the urinary tract and kidney development. Previous studies demonstrate an heterogeneous genetic pattern of VUR. In fact no single major locus or gene for primary VUR has been identified. It is likely that different forms of VUR with different genetic determinantes are present. Moreover genetic studies of syndromes with associated VUR have revealed several possible candidate genes involved in the pathogenesis of VUR and related urinary tract malformations. Mutations in genes essential for urinary tract morphogenesis are linked to numerous congenital syndromes, and in most of those VUR is a feature. The Authors provide an overview of the developmental processes leading to the VUR. The different genes and signaling pathways controlling the embryonal urinary tract development are analyzed. A better understanding of VUR genetic bases could improve the management of this condition in children.

Auditory and vestibular phenotypes associated with GATA3 mutation

OBJECTIVE

To report the auditory and vestibular phenotypes of patients with GATA3 mutation.

STUDY DESIGN

Case series of 6 patients.

SETTING

Tertiary referral center.

PATIENTS

All patients had the classic triad of GATA3 deficiency: hypoparathyroidism, hearing loss, and renal dysplasia. Patients (29-60 yr old; mean age, 42.5 yr; 3 male and 3 female subjects) were confirmed to have heterozygous mutations involving GATA3 by Sanger sequencing.

INTERVENTIONS

Behavioral audiometry, distortion product otoacoustic emissions (DPOAEs), and auditory brainstem responses (ABRs) were used to assess hearing. Rotational vestibular testing was used to assess vestibular function.

RESULTS

All patients with GATA3 mutation presented with hearing loss during childhood. The mean 3-frequency (0.5/1/2 kHz) pure tone average was 67 dB HL (range, 50-83 dB HL; SD, 9.3). The average speech discrimination score was 73% (range, 36%-100%; SD, 15.9). DPOAEs were absent in all patients. ABRs were remarkably robust and provided no evidence of retrocochlear dysfunction. Some patients complained of dizziness, but rotary chair testing was normal across participants for whom testing occurred.

CONCLUSION

Patients with GATA3 mutation present with early-onset sensorineural hearing loss (SNHL). DPOAEs were absent, supporting outer hair cell dysfunction, whereas ABRs were present and robust. Rotational vestibular testing revealed no evidence of abnormal horizontal semicircular canal function.

Co-occurrence of 22q11 deletion syndrome and HDR syndrome

22q11 deletion syndrome is one of the most common chromosomal deletion syndromes and is usually caused by a 1.5-3.0 Mb deletion at chromosome 22q11.2. It is characterized by hypocalcemia resulting from hypoplasia of the parathyroid glands, hypoplasia of the thymus, and defects of the cardiac outflow tract. We encountered a Japanese boy presenting with an unusually severe phenotype of 22q11 deletion syndrome, including progressive renal failure and severe intellectual disabilities. Diagnostic testing using fluorescent in situ hybridization revealed deletion of the 22q11 region, but this did not explain the additional complications. Copy number analysis was therefore performed using whole genome single nucleotide polymorphism (SNP) assay, which identified an additional de novo deletion at 10p14. This region is the locus for hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome caused by haploinsufficiency of GATA3. Together, these two syndromes sufficiently explain the patient's phenotype. This is the first known case report of the co-occurrence of 22q11 deletion syndrome and HDR syndrome. As the two syndromes overlap clinically, this study indicates the importance of carrying out careful clinical and genetic assessment of patients with atypical clinical phenotypes or unique complications. Unbiased genetic analysis using whole genome copy number SNP arrays is especially useful for detecting such rare double mutations.

Lower urinary tract development and disease

Congenital anomalies of the lower urinary tract (CALUT) are a family of birth defects of the ureter, the bladder, and the urethra. CALUT includes ureteral anomaliesc such as congenital abnormalities of the ureteropelvic junction (UPJ) and ureterovesical junction (UVJ), and birth defects of the bladder and the urethra such as bladder-exstrophy-epispadias complex (BEEC), prune belly syndrome (PBS), and posterior urethral valves (PUVs). CALUT is one of the most common birth defects and is often associated with antenatal hydronephrosis, vesicoureteral reflux (VUR), urinary tract obstruction, urinary tract infections (UTI), chronic kidney disease, and renal failure in children. Here, we discuss the current genetic and molecular knowledge about lower urinary tract development and genetic basis of CALUT in both human and mouse models. We provide an overview of the developmental processes leading to the formation of the ureter, the bladder, and the urethra, and different genes and signaling pathways controlling these developmental processes. Human genetic disorders that affect the ureter, the bladder and the urethra and associated gene mutations are also presented. As we are entering the postgenomic era of personalized medicine, information in this article may provide useful interpretation for the genetic and genomic test results collected from patients with lower urinary tract birth defects. With evidence-based interpretations, clinicians may provide more effective personalized therapies to patients and genetic counseling for their families.

Clinical description of a patient carrying the smallest reported deletion involving 10p14 region

Haploinsufficiency of a region located distal to 10p14 designated HDR1, is responsible for hypoparathyroidism, sensorineural deafness, and renal anomalies (HDR syndrome). Haploinsufficiency of a more proximal region, located on 10p13-10p14, designated as DGCR2 is associated with congenital heart defects and thymus hypoplasia/aplasia or T cell defect. We describe a patient showing facial dysmorphisms, delayed psychomotor development and bilateral sensorineural hearing loss and carrying a 10p14 deletion, the smallest deletion found in the literature so far. Our patient, carrying a partial deletion of the DGCR2 region and of the HDR1 region, including the GATA3 gene, showed, unexpectedly, only few of the clinical features of DiGeorge 2 syndrome (psychomotor retardation, palpebral ptosis, epicanthic folds, anteverted nares, cryptorchidism, hand/foot abnormalities) and did not show other typical signs, such as cardiac defect, cleft palate, and abnormal T cell levels. Of the three characteristic features of the HDR syndrome, our patient had only sensorineural deafness. On the basis of the revision of the other cases reported in the literature with a deletion including the 10p14 region, we suggest that GATA3 haploinsufficiency, although not recorded for each patient, is responsible for deafness. The present case shows that even this small 10p deletion is responsible for a specific phenotype. We also underline the importance of CGH-array, in order to obtain a more precise physical mapping of the 10p deletions and an accurate genotype-phenotype correlation.