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Spondylo-epi-metaphyseal dysplasias (SEMDs) are a clinically and genetically heterogeneous group of skeletal dysplasias characterized by short stature and abnormal modeling of the spine and long bones. A novel form of rhizomelic skeletal dysplasia, Ain-Naz type, associated with a homozygous variant in GNPNAT1 was recently identified. Herein, we report an Egyptian patient, offspring of consanguineous parents, who presented with a severe form of unclassified SEMD. Whole exome sequencing identified a novel homozygous variant in exon 3, c.77TG, (p.Phe26Cys) in GNPNAT1, that was confirmed by Sanger sequencing and both parents were found to be heterozygous for the identified variant. Main features included severe short stature, rhizomelic limb shortening, and wide flared metaphysis. Short broad long bones, brachydactyly, delayed epiphyseal ossification of long bones, advanced bone age, and immunodeficiency were additional findings expanding the clinical phenotype described in the previously reported family. We conclude that variants in the GNPNAT1 gene cause an autosomal recessive form of SEMD resembling Desbuquois like dysplasia caused by PGM3, which is involved in the same pathway as GNPNAT1.

Ectodermal dysplasia (ED) is a diverse group of genetic disorders caused by congenital defects of two or more ectodermal-derived body structures, namely, hair, teeth, nails, and some glands, e.g., sweat glands. Molecular pathogenesis of ED involves mutations of genes encoding key proteins of major developmental pathways, including ectodysplasin (EDA) and wingless-type (WNT) pathways. The most common ED phenotype is hypohidrotic/anhidrotic ectodermal dysplasia (HED) featuring hypotrichosis, hypohidrosis/anhidrosis, and hypodontia. Molecular diagnosis is fundamental for disease management and emerging treatments. We used targeted next generation sequencing to study EDA, EDAR, EDARADD, and WNT10A genes in 45 Egyptian ED patients with or without hypohidrosis. We present genotype and phenotype data of 28 molecularly-characterized patients demonstrating genetic heterogeneity, variable expressivity, and intrafamilial phenotypic variability. Thirteen mutations were reported, including four novel EDA mutations, two novel EDARADD, and one novel EDAR mutations. Identified mutations congregated in exons encoding key functional domains. EDA is the most common gene contributing to 85% of the identified Egyptian ED genetic spectrum, followed by EDARADD (10%) and EDAR (5%). Our cohort represents the first and largest cohort from North Africa where more than 60% of ED patients were identified emphasizing the need for exome sequencing to explore unidentified cases.

Introduction Primary hyperoxaluria type 1 (PH1) is a rare disease that is challenged by the overproduced oxalate and commonly presented with radiopaque renal stones or obstructive uropathy. This study aimed to report clinical presentations, renal replacement therapy (RRT) and outcome of PH1 in end stage kidney disease (ESKD) children. Methods This is an observational cohort study. Data of 22 patients with ESKD due to PH1 were analyzed at Pediatric Nephrology Unit, Faculty of Medicine Cairo University. Results Infantile onset patients (n=10) had worst renal outcome (80% with ESRD at presentation, p=0.019) and worse patient outcome (mortality 40%, p=0.016) than juvenile (n=9) and late onset (PH1 n=3) patients. RRT modalities include peritoneal dialysis (PD) in 7 (31.8%), hemodialysis (HD) in 11(50 %) and, combined liver kidney transplantation (CLKT) in 4 (18.2%) patients. Infectious complications were encountered in 42.8% of PD patients. Better HD adequacy was observed with frequent HD (n=6) and/or HD via arteriovenous fistula (AVF) than with infrequent dialysis (n=5) and/or via central venous line (CVL) (P =0.0001 & 0.0047 respectively). Morbidity and mortality (infection related) rates of the whole cohort were 63.6% and 31.8% respectively. Conclusions Clinical presentation of PH1 varies according to the age of onset (infantile onset being the most aggressive form). Aggressive HD (better through AVF) is needed to achieve acceptable HD adequacy, PD was challenged by infection. Infection found to be the main cause of mortality even after successful CLKT. This article is protected by copyright. All rights reserved.