Robinow syndrome: report of two cases and review of the literature

Aarskog-Scott syndrome: phenotypic and genetic heterogeneity

Aarskog-Scott syndrome (AAS) is a rare developmental disorder which primarily affects males and has a relative prevalence of 1 in 25,000 in the general population. AAS patients usually present with developmental complications including short stature and facial, skeletal and urogenital anomalies. The spectrum of genotype-phenotype correlations in AAS is unclear and mutations of the FGD1 gene on the proximal short arm of chromosome X account for only 20% of the incidence of the disorder. Failure to identify pathogenic variants in patients referred for FGD1 screening suggests heterogeneity underlying pathophysiology of the condition. Furthermore, overlapping features of AAS with several other developmental disorders increase the complexity of diagnosis. Cytoskeletal signaling may be involved in the pathophysiology of AAS. The FGD1 protein family has a role in activation of CDC42 (Cell Division Control protein 42 homolog) which has a core function in remodeling of extracellular matrix and the transcriptional activation of many modulators of development. Therefore, mutations in components in the EGFR1 (Epidermal Growth Factor Receptor 1) signaling pathway, to which CDC42 belongs, may contribute to pathophysiology. Parallel sequencing strategies (so-called next generation sequencing or high throughput sequencing) enables simultaneous production of millions of sequencing reads that enormously facilitate cost-effective identification of cryptic mutations in heterogeneous monogenic disorders. Here we review the source of phenotypic and genetic heterogeneity in the context of AAS and discuss the applicability of next generation sequencing for identification of novel mutations underlying AAS.

Tomographic Study of the Malformation Complex in Correlation With the Genotype in Patients With Robinow Syndrome: Review Article

We aimed to understand the etiology behind the abnormal craniofacial contour and other clinical presentations in a number of children with Robinow syndrome. Seven children with Robinow syndrome were enrolled in this study (autosomal recessive caused by homozygous mutations in the ROR2 gene on chromosome 9q22, and the autosomal dominant caused by heterozygous mutation in the WNT5A gene on chromosome 3p14). In the autosomal recessive (AR) group, the main clinical presentations were intellectual, disability, poor schooling achievement, episodes of headache/migraine, and poor fine motor coordinative skills, in addition to massive restrictions of the spine biomechanics causing effectively the development of kyposcoliosis and frequent bouts of respiratory infections. Three-dimensional reconstruction computed tomography scan revealed early closure of the metopic and the squamosal sutures of skull bones. Massive spinal malsegmentation and unsegmented spinal bar were noted in the AR group. In addition to severe mesomelia and camptodactyly, in the autosomal dominant (AD) group, no craniosynostosis but few Wormian bones and the spine showed limited malsegemetation, and no mesomelia or camptodactyly have been noted. We wish to stress that little information is available in the literature regarding the exact pathology of the cranial bones, axial, and appendicular malformations in correlation with the variable clinical presentations in patients with the 2 types of Robinow syndrome.

Dental management and orofacial manifestations of a patient with Robinow Syndrome

Robinow syndrome (RS) is an extremely rare condition. Characteristic craniofacial findings of RS include a fetal facial appearance, ear abnormalities and oral findings. The aim of this case report was to evaluate the oral findings of a 26-year-old man with RS and to describe the dental treatments performed. The patient had short stature, vertebral anomalies, short and broad fingers, a fetal facial appearance, gingival hyperplasia, fissured tongue, caries and multiple impacted teeth. Periodontal and restorative dental treatments were performed under aseptic conditions with due precautions. No surgical treatment was performed to the impacted teeth because of the lack of symptoms.

A new horizon of moyamoya disease and associated health risks explored through RNF213

The cerebrovascular disorder moyamoya disease (MMD) was first described in 1957 in Japan, and is typically considered to be an Asian-specific disease. However, it is globally recognized as one of the major causes of childhood stroke. Although several monogenic diseases are known to be complicated by Moyamoya angiopathy, the ring finger protein 213 gene (RNF213) was identified as a susceptibility gene for MMD. RNF213 is unusual, because (1) it induces MMD with no other recognizable phenotypes, (2) the RNF213 p.R4810K variant is an Asian founder mutation common to Japanese, Korean and Chinese with carrier rates of 0.5–2 % of the general population but a low penetrance, and (3) it encodes a relatively largest proteins with a dual AAA+ ATPase and E3 Ligase activities. In this review, we focus on the genetics and genetic epidemiology of RNF213, the pathology of RNF213 R4810K, and the molecular functions of RNF213, and also address the public health contributions to current unresolved issues of MMD. We also emphasize the importance of a more updated definition for MMD, of qualified cohort studies based on genetic epidemiology and an awareness of the ethical issues associated with genetic testing of carriers.

Mutations in DVL1 cause an osteosclerotic form of Robinow syndrome

Robinow syndrome (RS) is a phenotypically and genetically heterogeneous condition that can be caused by mutations in genes encoding components of the non-canonical Wnt signaling pathway. In contrast, germline mutations that act to increase canonical Wnt signaling lead to distinctive osteosclerotic phenotypes. Here, we identified de novo frameshift mutations in DVL1, a mediator of both canonical and non-canonical Wnt signaling, as the cause of RS-OS, an RS subtype involving osteosclerosis, in three unrelated individuals. The mutations all delete the DVL1 C terminus and replace it, in each instance, with a novel, highly basic sequence. We showed the presence of mutant transcript in fibroblasts from one individual with RS-OS and demonstrated unimpaired protein stability with transfected GFP-tagged constructs bearing a frameshift mutation. In vitro TOPFlash assays, in apparent contradiction to the osteosclerotic phenotype, revealed that the mutant allele was less active than the wild-type allele in the canonical Wnt signaling pathway. However, when the mutant and wild-type alleles were co-expressed, canonical Wnt activity was 2-fold higher than that in the wild-type construct alone. This work establishes that DVL1 mutations cause a specific RS subtype, RS-OS, and that the osteosclerosis associated with this subtype might be the result of an interaction between the wild-type and mutant alleles and thus lead to elevated canonical Wnt signaling.

Identification of a novel causative mutation in the ROR2 gene in a Lebanese family with a mild form of recessive Robinow syndrome

Autosomal recessive Robinow syndrome (OMIM 268310) is a condition caused by mutations in the ROR2 gene, the receptor tyrosine kinase-like orphan receptor 2. The main characteristic features are: a face resembling that of a fetus, cleft lip and palate, mesomelic limb shortening, a micropenis in males, hydronephrosis or urinary tract infections, and skeletal and vertebral anomalies. This study reports two sisters from a consanguineous Lebanese family with an autosomal recessive Robinow syndrome. Both presented with short stature, dysmorphic facial features, and mild bone abnormalities. One of the affected girls had a malformation of her right hand: a mesoaxial polydactyly combined with a syndactyly of the 3rd and 4th fingers, and a short right 3rd metacarpal bone. Molecular analysis of the ROR2 gene revealed the presence of a previously undescribed missense mutation: p.R272C (c.814C>T), in the cysteine-rich domain of the protein. These patients are compared with other cases, and a phenotype-genotype correlation is discussed.

Robinow syndrome

Robinow syndrome is a rare autosomal recessive mesomelic dwarfism with just more than 100 cases reported in the literature so far. The lower extremity is spared with skeletal deformity usually confined to the forearm, hand, and the dorsal spine. Diagnosis is made easily in the early childhood by the typical "fetal facies" appearance, which disappears to a certain extent as the patient grows. The author reports two cases of this entity with vertebral segmentation defects, rib fusion, and typical severe brachymelia and facial features.