Further delineation of Wiedemann-Rautenstrauch syndrome linked with POLR3A.

Wiedemann-Rautenstrauch Syndrome (WRS; MIM 264090) is an extremely rare and highly heterogeneous syndrome that is inherited in a recessive fashion. The patients have hallmark features such as prenatal and postnatal growth retardation, short stature, a progeroid appearance, hypotonia, facial dysmorphology, hypomyelination leukodystrophy, and mental impairment. Biallelic disease-causing variants in the RNA polymerase III subunit A (POLR3A) have been associated with WRS. Here, we report the first identified cases of WRS syndrome with novel phenotypes in three consanguineous families (two Omani and one Saudi) characterized by biallelic variants in POLR3A. Using whole-exome sequencing, we identified one novel homozygous missense variant (NM_007055: c.2456C>T; p. Pro819Leu) in two Omani families and one novel homozygous variant (c.1895G>T; p Cys632Phe) in Saudi family that segregates with the disease in the POLR3A gene. In silico homology modeling of wild-type and mutated proteins revealed a substantial change in the structure and stability of both proteins, demonstrating a possible effect on function. By identifying the homozygous variants in the exon 14 and 18 of the POLR3A gene, our findings will contribute to a better understanding of the phenotype-genotype relationship and molecular etiology of WRS syndrome.

Segmental spinal dysgenesis with open spinal dysraphism and Chiari II features, case report.

Segmental spinal dysgenesis (SSD) is a complex spinal anomaly characterized by localized dysgenesis of the lumbar or thoracolumbar spine, and severe congenital kyphosis or kyphoscoliosis. We describe a newborn who presented with severe congenital paraplegia and a lumbar mass. Magnetic resonance imaging confirmed SSD type II associated with open spinal dysraphism and intracranial Chiari II features; this association has not been reported. The association modifies the disease management and outcome. The previous classification of SSD could be revisited based on our case.

PDCD6IP, encoding a regulator of the ESCRT complex, is mutated in microcephaly.

Primary microcephaly (PM) is a highly heterogeneous neurodevelopmental disorder with many contributing risk genes and loci identified to date. We report a consanguineous family with PM, intellectual disability and short stature. Using whole exome sequencing, we identified a homozygous frameshift variant in programmed cell death 6 interacting protein (PDCD6IP, c.154_158dup; p.Val54Profs*18). This gene, PDCD6IP, plays an important role in the endosomal sorting complexes required for transport (ESCRT) pathway in the abscission stage of cytokinesis and apoptosis, and is required for normal brain development in mice. The clinical features observed in our patient were similar to the phenotypes observed in mouse and zebrafish models of PDCD6IP mutations in previous studies. This study provides evidence that clinical manifestations of PDCD6IP mutations as seen in our patients with PM and ID may be a novel cause for neurodevelopmental disorders.

A mendelian form of neural tube defect caused by a de novo null variant in SMARCC1 in an identical twin.

Neural tube defects (NTDs) are among the most common birth defects in humans and yet their molecular etiology remains poorly understood. NTDs are believed to result from the complex interaction of environmental factors with a multitude of genetic risk factors in a classical multifactorial disease model. Mendelian forms of NTDs in which single variants are sufficient to cause the disease are extremely rare. We report a monozygotic twin with severe NTDs (occipital encephalocele and myelomeningocele) and a shared de novo, likely truncating, variant in SMARCC1. RTPCR analysis suggests the potential null nature of the variant attributed to nonsense-mediated decay. SMARCC1 is extremely constrained in humans and encodes a highly conserved core chromatin remodeler, BAF155. Mice that are heterozygous for a null allele or homozygous for a hypomorphic allele develop severe NTDs in the form of exencephaly. This is the first report of SMARCC1 mutation in humans, and it shows a critical and conserved requirement for intact BAF chromatin remodeling complex in neurulation. Ann Neurol 2018;83:433-436.

Renal lymphangiomatosis, a rare differential diagnosis for autosomal recessive polycystic kidney disease in pediatric patients.

Renal lymphangiomatosis is a rare, benign malformation, characterized by developmental malformation of the perirenal, peripelvic, and intrarenal lymphatics. Radiologist knowledge of the unique radiological features of this entity helps patient's safety in terms of management. We study the case of a 27-month-old boy presented to the emergency department with upper respiratory tract infection. He had a high blood pressure and had been diagnosed earlier with autosomal recessive polycystic kidney disease based on renal ultrasound findings. Because the clinical presentation and laboratory work of the patient did not support the diagnosis of autosomal recessive polycystic kidney disease, further, extensive work-up was performed, which confirmed the diagnosis of renal lymphangiomatosis. This case report emphasizes the imaging features of this rare entity to promote early diagnosis and better patient care.

Intrahepatic splenosis mimicking hepatocellular carcinoma in a cirrhotic liver.

We report a patient who has a cirrhotic liver secondary to hepatitis C virus infection with a liver lesion incidentally found on routine liver ultrasound. The patient had a history of splenectomy 30 years earlier. The magnetic resonance imaging (MRI) characteristics suggested the diagnosis of intrahepatic splenosis, which is confirmed by core needle biopsy. Knowledge of these imaging findings makes this entity important to be considered in the differential diagnosis of a hepatic tumor in the presence of a history of splenic trauma or surgery.