Broadening the phenotype of LRP2 mutations: a new mutation in LRP2 causes a predominantly ocular phenotype suggestive of Stickler syndrome.

Two siblings, from a consanguineous Iraqi family, were investigated to identify the underlying genetic cause of their high myopia, esotropia, vitreous changes and cataract. Subsequent investigation identified low molecular weight proteinuria as part of their syndrome. Exome sequencing of one of the probands revealed a new non-synonymous variant in the LRP2 gene. Sanger sequencing confirmed the mutation and segregation in the family. No mutation was identified in COL9A1/2, COL11A1/2, or COL2A1 genes. The variant (c.11483A>G; p.Asp3828Gly) is predicted to be damaging and is conserved among vertebrate species. Mutations in LRP2 have been shown to cause the Donnai-Barrow syndrome (DBS) or facio-oculo-acoustico-renal (FOAR) syndrome, a syndrome associated with facial dysmorphism, ocular anomalies, sensorineural hearing loss, low molecular weight proteinuria, and diaphragmatic hernia and absent corpus callosum, although there is variability in the expression of some features. This family shows a milder phenotype with a predominant eye phenotype similar to the Stickler syndrome and only a few features of the DBS, including microglobulinuria. The presence of microglobulinuria was only detected after molecular results were known. In conclusion, with the identification of a new mutation in LRP2 associated with a predominant eye phenotype similar to the Stickler syndrome, we have broadened the phenotypic spectrum of LRP2 mutations.

Schrauwen I ，Sommen M ，Claes C ，Pinner J ，Flaherty M ，Collins F ，Van Camp G ... -  《-》

The distinct optic disk and peripapillary appearance in Donnai-Barrow syndrome.

Khan AO ，Ghazi NG 《-》

Variable expression pattern in Donnai-Barrow syndrome: Report of two novel LRP2 mutations and review of the literature.

Donnai-Barrow syndrome (DBS; MIM 222448) is characterized by typical craniofacial anomalies (major hypertelorism with bulging eyes), high grade myopia, deafness and low molecular weight proteinuria. The disorder results from mutations in the low density lipoprotein receptor-related protein 2 gene LRP2 that maps to chromosome 2q31.1. LRP2 encodes megalin, a multi-ligand endocytic receptor. Herein, we describe the clinical presentation of 4 patients from 2 unrelated Saudi families. Two novel LRP2 mutations, a homozygous nonsense mutation (c.4968C>G; p.Tyr1656*) and a missense mutation (c.12062G>A; p.Cys4021Tyr), were detected in the first and second family respectively. Interestingly, intrafamilial phenotypic variability was observed in one family, while DBS features were atypical in the second family. Differential diagnosis of DBS includes several syndromes associating hypertelorism with high grade myopia, and several syndromal forms of CDH, which are briefly summarized in this study.

Khalifa O ，Al-Sahlawi Z ，Imtiaz F ，Ramzan K ，Allam R ，Al-Mostafa A ，Abdel-Fattah M ，Abuharb G ，Nester M ，Verloes A ，Al-Zaidan H ... -  《-》

A prenatally diagnosed case of Donnai-Barrow syndrome: Highlighting the importance of whole exome sequencing in cases of consanguinity.

Donnai-Barrow syndrome (DBS) is an autosomal recessive disorder characterized by typical craniofacial features, vision and hearing loss, intellectual disability, agenesis of the corpus callosum (ACC), congenital diaphragmatic hernia (CDH), and omphalocele. This condition is associated with loss-of-function mutations in the LRP2 gene. Few cases have been described in the literature. In our case, CDH and ACC were prenatally diagnosed by ultrasound, and the fetus was the product of a first-degree union. Single-nucleotide polymorphism-microarray showed large regions of homozygosity. Whole exome sequencing (WES) was performed and revealed a homozygous frameshift pathogenic variant in LRP2 (c.6978dupG). Here, we present a case of DBS, which diagnosed prenatally via WES in a fetus with CDH and ACC.

Ozdemir H ，Plamondon J ，Gaskin P ，Asoglu MR ，Turan S ... -  《-》

In-depth phenotyping of a Donnai-Barrow patient helps clarify proximal tubule dysfunction.

Dachy A ，Paquot F ，Debray G ，Bovy C ，Christensen EI ，Collard L ，Jouret F ... -  《-》