Mutations in PRDM15 Are a Novel Cause of Galloway-Mowat Syndrome

BACKGROUND

Galloway-Mowat syndrome (GAMOS) is characterized by neurodevelopmental defects and a progressive nephropathy, which typically manifests as steroid-resistant nephrotic syndrome. The prognosis of GAMOS is poor, and the majority of children progress to renal failure. The discovery of monogenic causes of GAMOS has uncovered molecular pathways involved in the pathogenesis of disease.

METHODS

Homozygosity mapping, whole-exome sequencing, and linkage analysis were used to identify mutations in four families with a GAMOS-like phenotype, and high-throughput PCR technology was applied to 91 individuals with GAMOS and 816 individuals with isolated nephrotic syndrome. In vitro and in vivo studies determined the functional significance of the mutations identified.

RESULTS

Three biallelic variants of the transcriptional regulator PRDM15 were detected in six families with proteinuric kidney disease. Four families with a variant in the protein's zinc-finger (ZNF) domain have additional GAMOS-like features, including brain anomalies, cardiac defects, and skeletal defects. All variants destabilize the PRDM15 protein, and the ZNF variant additionally interferes with transcriptional activation. Morpholino oligonucleotide-mediated knockdown of Prdm15 in Xenopus embryos disrupted pronephric development. Human wild-type PRDM15 RNA rescued the disruption, but the three PRDM15 variants did not. Finally, CRISPR-mediated knockout of PRDM15 in human podocytes led to dysregulation of several renal developmental genes.

CONCLUSIONS

Variants in PRDM15 can cause either isolated nephrotic syndrome or a GAMOS-type syndrome on an allelic basis. PRDM15 regulates multiple developmental kidney genes, and is likely to play an essential role in renal development in humans.

Nephrological and urological complications of homozygous c.974G>A (p.Arg325Gln) OSGEP mutations

BACKGROUND

Galloway-Mowat syndrome (GAMOS) (OMIM #251300) is a severe autosomal recessive disease characterized by the combination of early-onset steroid-resistant nephrotic syndrome (SRNS) and microcephaly with brain anomalies caused by WDR73 as well as OSGEP, TP53RK, TPRKB, or LAGE3 mutations.

OBJECTIVE

We report on the hitherto undescribed urological and nephrological complications of the homozygous c.974G>A (p.Arg325Gln) OSGEP mutations in a 7-year-old Caucasian girl.

CASE DIAGNOSIS

The patient came to the attention of pediatric nephrology at the age of 3 years and 11 months, when she presented with status epilepticus due to profound hypomagnesemia (0.31 mmol/L, normal 0.65-1.05). A 24-h urine demonstrated a magnesium loss of 0.6 mmol/kg/day with associated proteinuria suggesting renal tubulopathy. Subsequently, she developed recurrent urinary tract infections (UTIs) and was diagnosed with neurogenic bladder dysfunction. The patient continued to have UTIs associated with seizures and sequential cultures growing multi-drug-resistant organisms despite of antibiotic prophylaxis. In addition, the proteinuria (median microalbumin/creatinine ratio 647 mg/mmol) increased, and she developed partial Fanconi syndrome. At age 7, she developed a large bladder calculus (3.3 × 3.2 cm) and three left non-obstructing renal calculi associated with elevated urinary cystine, hypercalciuria, and ongoing hypomagnesemia and required surgical intervention. Glomerular filtration rate (GFR) remained normal and she never developed frank nephrotic syndrome (average albumin 31 g/L).

CONCLUSIONS

It is unclear if patients with OSGEP mutations with tubular symptoms rather than nephrotic syndrome should be considered a different entity. Nephrological and urological complications of OSGEP mutations can be challenging and require a multidisciplinary approach.

Oesophageal atresia with a terminal deletion of chromosome 2q37.1

We herein report the case of a newborn girl with oesophageal atresia associated with cardiac and gastrointestinal anomalies, including patent ductus arteriosus, tracheomalacia, and gastro-oesophageal reflux with hiatus hernia. In addition, she had a terminal deletion of the long arm of chromosome 2, with a breakpoint of 2q37.1. The patient died following a cardiac arrest at 90 days of age. No cause of death was identified at autopsy.

Das Arterial-Tortuosity-Syndrom

The arterial tortuosity syndrome is a rare congenital disorder characterized by elongation and generalized tortuosity of the major arteries including the aorta. Associated clinical features consist of excessively stretchable skin and joint laxity which is indicative of a connective tissue disorder such as Ehlers-Danlos or Cutis laxa syndrome. The gene locus of the arterial tortuosity syndrome has recently been localised on chromosome 20q13; inheritance ist autosomal recessive. - We report on a newborn with arterial tortuosity syndrome and hiatal hernia, bilateral hip dislocation, inguinal hernias and diffuse tortuosity of the great arteries including the aorta. Known gene loci involved in Ehlers-Danlos syndrome, cutis laxa syndrome and other connective tissue disorders were excluded by specific DNA markers. By homozygosity mapping with polymorphic microsatellite markers it was possible to confirm the gene locus for the ATS on chromosome 20q13. In addition to the presentation of this patient, a review of the literature is presented.

Familial hiatal hernia in a large five generation family confirming true autosomal dominant inheritance

BACKGROUND

Familial hiatal hernia has only rarely been documented.

AIMS

To describe the pattern of inheritance of familial hiatal hernia within an affected family.

SUBJECTS

Thirty eight members of a family pedigree across five generations.

METHODS

All family members were interviewed and investigated by barium meal for evidence of a hiatal hernia.

RESULTS

Twenty three of 38 family members had radiological evidence of a hiatal hernia. No individual with a hiatal hernia was born to unaffected parents. In one case direct male to male transmission was shown.

CONCLUSIONS

Familial inheritance of hiatal hernia does occur. Evidence of direct male to male transmission points to an autosomal dominant mode of inheritance.

Paraoesophageal hernia in children: familial occurrence and review of the literature

Paraoesophageal hernia (PH) in children is a rare entity, and most reported cases refer to adult patients. Its etiology is not precisely known, but the hypothesis of its congenital origin is widely accepted. Similarly to other congenital diaphragmatic defects, PH follows a sporadic pattern of incidence in most cases. Familial occurrence of sliding hiatal herniae has been reported in more than 20 cases, but only one family with two members affected by PH was described in the literature. We present two pairs of siblings with the paraoesophageal type of hiatus hernia and discuss the clinical presentation of this anomaly in children.

Familial hiatus hernia and gastro-oesophageal reflux

This report describes a family in which the father and three children had a sliding hiatus hernia. In each case there was gastro-oesophageal reflux from the neonatal period which proved unresponsive to medical therapy, ultimately requiring anti-reflux surgery. The trait in this family supports an autosomal dominant genetic component to the infant hiatus hernia.

Kidney in Galloway-Mowat syndrome: clinical spectrum with description of pathology

The Galloway-Mowat syndrome, a rare inherited disorder, is characterized by congenital microcephaly with hypotonia and developmental delay, often hiatus hernia, and nephrotic syndrome manifested in infancy or in early childhood. The glomerular lesion has been poorly characterized in the few previous reports of this syndrome. We studied three siblings with microcephaly and nephrotic syndrome occurring during the first two weeks of life. Hematuria, glycosuria and renal failure were also present. Renal biopsy and postmortem specimens of two patients were studied. Glomerular structure was disorganized; capillary lumina were of varying calibers, capillary walls were adherent to one another, and mesangial zones were poorly demarcated. Glomerular basement membrane ultrastructure was markedly altered. The normal trilaminar structure was obscured or replaced by flocculent material; furthermore, 6 to 8 nm fibrils of unknown nature permeated the space between endothelial and epithelial cells. Non-glomerular basement membranes were unaltered in appearance. This syndrome apparently represents, in part, a new disorder of glomerular basement membrane formation and function.

[Genetic role in hernia of the esophageal hiatus. Description of the disease in 2 brothers]

Two brothers born 15 years apart from normal healthy parents were affected by esophageal hiatus hernia diagnosed at 4 and 8 months respectively. We found 37 other families with more than one member affected by EHH reported in the literature. Since the anomaly often runs asymptomatic, familiarity is probably more frequent than generally thought. The type of inheritance is still uncertain, but a multifactorial etiology is the most likely explanation.

Findings on barium swallow in younger siblings of children with hiatal hernia (partial thoracic stomach)

The results are presented of an investigation by barium swallow of 271 younger siblings of children with hiatal hernia (HH). The incidence of HH among younger siblings with a history of repeated vomiting and regurgitation was 41% and in those without symptoms was 4.3%.

[Familial forms of gastro-esophageal reflux]

Gastroesophageal reflux is a common disorder that can be responsible for respiratory disease and is not considered as an inherited condition. We report five families with several affected members. Other familial cases have been published and some authors have suggested that transmission occurs on an autosomal dominant basis. Only prospective studies could determine whether GER is an inherited disorder, but at present their feasibility is limited since currently available diagnostic investigations are not suitable for screening.

Familial occurrence of intrathoracic gastric volvulus

This report describes the first documented familial occurrence of gastric volvulus in two consecutive generations. Consideration is given to familial transmission of other foregut disorders. The report reviews the different types of gastric volvulus and considers their pathogenesis, clinical presentation, and treatment.

A girl with G syndrome and agenesis of the corpus callosum

We report on a female patient with G syndrome. The clinical expression is relatively severe and includes 2 manifestations not previously reported, ie, agenesis of the corpus callosum and umbilical hernia. These new findings support the notion that there is a developmental defect of the midline as the basis of the G syndrome.

Gastro-cutaneous syndrome: peptic ulcer/hiatal hernia, multiple lentigines/café-au-lait spots, hypertelorism, and myopia

We report the familial occurrence in a French Canadian family of peptic ulcer/hiatal hernia, multiple lentigines/café-au-lait spots, apparent hypertelorism, and myopia caused by a pleiotropic autosomal dominant gene with high penetrance and variable expressivity. Other probable but rarer components of the syndrome include ischemic heart disease, congenital heart disease, and maturity onset diabetes. Symptoms of peptic ulcer/hiatal hernia usually started in the second or third decade and were associated, as least in some examined individuals, with relatively increased acid secretion and abnormal dermatoglyphics.

Intramural diverticulosis of the esophagus in an eight-year-old boy

A third pediatric case of intramural diverticulosis of the esophagus is reported in an 8-year-old boy. A hiatal hernia, chronic nonspecific esophagitis and defective esophageal motility was also documented in his 10-year-old brother.