Diagnostic dilemmas in four infants with nephrotic syndrome, microcephaly and severe developmental delay

Whole-exome sequencing revealed a novel homozygous missense variant in OSGEP gene: a case report of Galloway-Mowat syndrome in Iran

Galloway-Mowat syndrome is a rare autosomal-recessive genetic disorder that is characterized by variety of complications such as neurological abnormalities and early-onset progressive kidney disease. Studies have been shown that pathogenic mutations in genes that belong to the KEOPS complex lead to Galloway-Mowat syndrome. Several pathogenic mutations in OSGEP gene, a member of the KEOPS complex, have been detected in Galloway-Mowat syndrome. Here we describe a 12-year-old male with intellectual disability, poor speech, seizures, microcephaly, and nephrotic syndrome that were in favor of Galloway-Mowat syndrome, born to a healthy Iranian consanguineous parents. Extracted genomic DNA from blood sample was used to perform whole-exome sequencing in the patient. The mutational screening revealed a novel homozygote OSGEP gene missense variant. Our finding established whole-exome sequencing as a valuable technic for the detection of rare variants.

Further delineation of the clinical spectrum of de novo TRIM8 truncating mutations

De novo mutations of the TRIM8 gene, which codes for a tripartite motif protein, have been identified using whole exome sequencing (WES) in two patients with epileptic encephalopathy (EE), but these reports were not sufficient to conclude that TRIM8 was a novel gene responsible for EE. Here we report four additional patients presenting with EE and de novo truncating mutations of TRIM8 detected by WES, and give further details of the patient previously reported by the Epi4K consortium. Epilepsy of variable severity was diagnosed in children aged 2 months to 3.5 years of age. All patients had developmental delay of variable severity with no or very limited language, often associated with behavioral anomalies and unspecific facial features or MRI brain abnormalities. The phenotypic variability observed in these patients appeared related to the severity of the epilepsy. One patient presented pharmacoresistant EE with regression, recurrent infections and nephrotic syndrome, compatible with the brain and kidney expression of TRIM8. Interestingly, all mutations were located at the highly conserved C-terminus section of TRIM8. This collaborative study confirms that TRIM8 is a novel gene responsible for EE, possibly associated with nephrotic syndrome. This report brings new evidence on the pathogenicity of TRIM8 mutations and highlights the value of data-sharing to delineate the phenotypic characteristics and biological basis of extremely rare disorders.

Congenital nephrotic syndrome in an infant with ALG1-congenital disorder of glycosylation

Congenital nephrotic syndrome (NS) in the newborn is most frequently related to mutations in genes specific for structural integrity of the glomerular basement membrane and associated filtration structures within the kidney, resulting in massive leakage of plasma proteins into the urine. Occurrence of congenital NS in a multi-system syndrome is less common. We describe the case of an infant with deteriorating neurological status, seizures, edema, and proteinuria who was found to have a mutation in gene ALG1 and a renal biopsy consistent with congenital NS. Furthermore, we briefly review rare existing case reports documenting congenital NS in patients with mutations in ALG1, and treatment strategies, including novel use of peritoneal dialysis.

Infantile nephrotic syndrome with microcephaly and global developmental delay: the Galloway Mowat Syndrome

The authors present the first case of Galloway Mowat Syndrome (GMS), a rare disorder comprising of nephrotic syndrome in association with microcephaly, from India. An 11-mo-old girl with microcephaly, developmental delay and nystagmus presented with nephrotic syndrome. The perinatal and neonatal periods had been uneventful. The renal biopsy revealed mesangial proliferation with IgM deposition, while MRI of the brain showed hypomyelination. Molecular diagnosis by polymerase chain reaction (PCR) did not reveal any pathogenic sequences in the exons and the flanking intronic regions of the NPHS2 gene and LAMB2 gene. The infant responded to prednisolone. GMS must be suspected whenever microcephaly and global developmental delay occurs in association with nephrotic syndrome, as this is important for prognostication and genetic counseling. The genetics of GMS remains an enigma and further research is required to delineate the pathogenesis of this disorder.

Neuropathological homology in true Galloway-Mowat syndrome

Galloway-Mowat syndrome is a rare condition that is likely hereditary though the underlying offending gene has not been identified, and is characterized by microcephaly and severe nephrotic syndrome culminating in childhood death. Some of the reported cases have abnormalities in neuronal migration and intractable seizures, but many of the described cases focus on the renal pathology and emphasize a diversity of clinical and pathological features. The case described herein includes a thorough neuropathological description, and when the neuroradiology and neuropathology of the previously published cases is scrutinized, a fairly consistent clinical and neuropathological phenotype emerges.

Analysis of genes encoding laminin beta2 and related proteins in patients with Galloway-Mowat syndrome

Galloway-Mowat syndrome (GMS) is a rare autosomal recessive disorder characterized by early onset nephrotic syndrome and microcephaly with various anomalies of the central nervous system. GMS likely represents a heterogeneous group of disorders with hitherto unknown genetic etiology. The clinical phenotype to some extent overlaps that of Pierson syndrome (PS), which comprises congenital nephrotic syndrome and distinct ocular abnormalities but which may also include neurodevelopmental deficits and microcephaly. PS is caused by mutations of LAMB2, the gene encoding laminin beta2. We hypothesized that GMS might be allelic to PS or be caused by defects in proteins that interact with laminin beta2. In a cohort of 18 patients with GMS or a GMS-like phenotype we therefore analyzed the genes encoding laminin beta2 (LAMB2), laminin alpha5 (LAMA5), alpha3-integrin (ITGA3), beta1-integrin (ITGB1) and alpha-actinin-4 (ACTN4), but we failed to find causative mutations in these genes. We inferred that LAMA5, ITGA3, ITGB1, and ACTN4 are not directly involved in the pathogenesis of GMS. We excluded LAMB2 as a candidate gene for GMS. Further studies are required, including linkage analysis in families with GMS to identify genes underlying this disease.

Congenital disorder of glycosylation-X: clinicopathologic study of an autopsy case with distinct neuropathologic features

Congenital disorders of glycosylation are a recently recognized group of inherited, multisystem disorders caused by aberrant biosynthesis of glycoproteins. We report the clinical and postmortem findings in a 3-year-old boy with a history of multiple medical issues including developmental delay, epilepsy, chronic protein-losing enteropathy, respiratory failure, nephropathy, coagulopathy, and cardiomyopathy. As part of the workup, isoelectric focusing for congenital disorders of glycosylation showed carbohydrate-deficient transferrin with the mono-oligo/dioligo ratio of 0.700 (normal, 0.075-0.109), indicating an increased level of abnormally glycosylated transferrin. After supportive care, he died secondary to multisystem complications of his disease. General autopsy findings were notable for micronodular liver cirrhosis with iron overload, myocardial ischemia and calcification, and hypertrophied glomeruli. Examination of the brain revealed cerebral and cerebellar atrophy, diffuse astrogliosis, and meningeal fibrosis. This article reveals complete autopsy findings of untyped congenital disorders of glycosylation, congenital disorders of glycosylation-x, with an undefined metabolic basis.

Cranial ultrasound in metabolic disorders presenting in the neonatal period: characteristic features and comparison with MR imaging

BACKGROUND AND PURPOSE

Brain imaging is an integral part of the diagnostic work-up for metabolic disorders, and the bedside availability of cranial ultrasonography (cUS) allows very early brain imaging in symptomatic neonates. Our aim was to investigate the role and range of abnormalities seen on cUS in neonates presenting with metabolic disorders. A secondary aim, when possible, was to address the question of whether brain MR imaging is more informative by comparing cUS to MR imaging findings.

MATERIALS AND METHODS

Neonates with a metabolic disorder who had at least 1 cUS scan were eligible. cUS images were reviewed for anatomic and maturation features, cysts, calcium, and other abnormalities. When an MR imaging scan had been obtained, both sets of images were compared.

RESULTS

Fifty-five infants (35 also had MR imaging) were studied. The most frequent findings were in oxidative phosphorylation disorders (21 cUS and 12 MR imaging): ventricular dilation (11 cUS and 6 MR imaging), germinolytic cysts (GLCs; 7 cUS and 5 MR imaging), and abnormal white matter (7 cUS and 6 MR imaging); in peroxisomal biogenesis disorders (13 cUS and 9 MR imaging): GLCs (10 cUS and 6 MR imaging), ventricular dilation (10 cUS and 5 MR imaging), abnormal cortical folding (8 cUS and 7 MR imaging), and lenticulostriate vasculopathy (8 cUS); in amino acid metabolism and urea cycle disorders (14 cUS and 11 MR imaging): abnormal cortical folding (9 cUS and 4 MR imaging), abnormal white matter (8 cUS and 8 MR imaging), and hypoplasia of the corpus callosum (7 cUS and 6 MR imaging); in organic acid disorders (4 cUS and 2 MR imaging): periventricular white matter echogenicity (2 cUS and 1 MR imaging); and in other disorders (3 cUS and 1 MR imaging): ventricular dilation (2 cUS and 1 MR imaging). cUS findings were consistent with MR imaging findings. cUS was better for visualizing GLCs and calcification. MR imaging was more sensitive for subtle tissue signal intensity changes in the white matter and abnormality in areas difficult to visualize with cUS, though abnormalities of cortical folding suggestive of polymicrogyria were seen on cUS.

CONCLUSION

A wide range of abnormalities is seen using cUS in neonatal metabolic disorders. cUS is a reliable bedside tool for early detection of cysts, calcium, structural brain abnormalities, and white matter echogenicity, all suggestive of metabolic disorders.

Congenital disorders of glycosylation type I: a rare but new cause of hyperechoic kidneys in infants and children due to early microcystic changes

BACKGROUND

There are numerous causes of bilateral hyperechoic kidneys. Congenital disorders of glycosylation (CDGs) are a rapidly growing family of inherited disorders due to defects in the synthesis of the glycans of glycoproteins or other glycoconjugates.

OBJECTIVE

To describe renal sonographic abnormalities in CDG type I in infants and children.

MATERIAL AND METHODS

A retrospective study of renal US in 12 infants and children: 8 CDG-Ia (6 multivisceral forms, 2 neurological forms), 2 CDG-Ib, and 2 CDG-Ix, with detailed functional renal tests in 6. Histology of the kidneys of one 35-week fetus with CDG-Ia was available.

RESULTS

Renal US was normal in the two children with the neurological form of CDG-Ia. All patients with the multivisceral form of CDG-Ia or with CDG-Ib showed increased cortical echogenicity, and/or abnormal pyramids (small +/- hyperechoic). The two patients with CDG-Ix showed predominant involvement of the medulla, with inverted corticomedullary differentiation in one. Kidney size was normal in all but two patients. The fetal kidneys exhibited diffuse microcysts arising from the distal tubules.

CONCLUSIONS

Hyperechoic kidneys are common in CDG-I patients, contrasting with grossly preserved renal function. The US pattern seems to differ slightly according to the type of CDG-I, and is consistent with microcystic changes of the renal parenchyma, which occur prenatally, and may be due to ciliary dysfunction secondary to altered glycosylation of tubular glycoproteins. CDG-I, which remains largely underdiagnosed at present, should be added to the causes of hyperechoic kidneys in children, especially in cases of multivisceral involvement, after ruling out other more frequent causes.

Late-onset growth restriction in Galloway-Mowat syndrome: a case report

Galloway-Mowat syndrome (GMS) is a rare autosomal recessive disorder and is characterized by marked intrauterine growth retardation, central nervous system anomalies, and early onset nephrotic syndrome. Of the reported cases in the literature, all were diagnosed postnatally. We describe a case of GMS in which only late-onset intrauterine growth restriction was detected by prenatal ultrasound. In her fourth pregnancy, the mother had delivered a male baby with clinical features of GMS who died at seven months of age due to early onset of nephrotic syndrome. In her fifth pregnancy, serial ultrasound examinations were normal during the first and second trimester of pregnancy. Growth restriction and microcephaly were not detectable until 28 to 32 weeks' gestation. At 40 weeks' gestation, a female baby was born with dysmorphic features of GMS. Nephrotic syndrome developed after birth and renal biopsy revealed minimal change nephrotic syndrome. The prenatal course of this case suggests GMS may not be diagnosed in early pregnancy and the only abnormality detected before birth was intrauterine growth restriction.

Congenital disorder of glycosylation type Ia: a clinicopathological report of a newborn infant with cerebellar pathology

Congenital disorders of glycosylation (CDG) represent a newly delineated group of inherited multisystem disorders characterized by defective glycoprotein biosynthesis. In the present study we report and discuss the clinical and neuropathological findings in a newborn with CDG type Ia (CDG-Ia). The patient presented mild dysmorphic facial features, inverted nipples, progressive generalized edema, hypertrophic cardiomyopathy, hepatosplenomegaly, muscular hypotonia and had severe hypoalbuminemia. Deficiency of phosphomannomutase (PMM)-2 activity was detected. Molecular analysis showed V231M/T237R mutations of the PMM2 gene. Muscular biopsy, disclosed myopathic alterations with myofibrillar disarray by electron microscopy. The patient died at 1 month of age of circulatory and respiratory failure. Autopsy showed liver fibrosis and renal abnormalities. Neuropathological abnormalities were mainly confined to the cerebellum. Histological and immunocytochemical examination of cerebellar tissue showed partial atrophy of cerebellar folia with severe loss of Purkinje cells, granular cell depletion and various morphological changes in the remaining Purkinje cells and their dendritic arborization. Autopsy findings confirm the complexity of the CDG-Ia syndrome, and indicate that CDG-Ia is a distinct disease entity, which can be differentiated from other neurological disorders and other types of CDG, not only clinically, but also based on unique pathological findings. The data proved useful in determining the underlying disease process associated with a defective N-glycosylation pathway.

Microcephaly, cerebellar atrophy, and focal segmental glomerulosclerosis in two brothers: a possible mild form of Galloway-Mowat syndrome

We report two brothers with microcephaly, cerebellar atrophy, and focal segmental glomerulosclerosis. The elderbrother showed nephrotic syndrome from 2 years of age and died of renal failure at 8 years of age. The younger brother showed mild proteinuria from 2 years of age, and his renal function was still preserved at 15 years of age. We propose that our patients may be affected with a mild form of Galloway-Mowat syndrome or another autosomal recessive syndrome with focal segmental glomerulosclerosis and central nervous system abnormalities.