Retinitis pigmentosa, mental retardation, marked short stature, and brachydactyly in two sibs

A novel small deletion in CWC27 gene associated with CWC27-related spliceosomeopathy

BACKGROUND

CWC27-related spliceosomeopathy is a rare autosomal recessive disorder with only 14 patients have been reported. It is characterized by retinal degeneration, short stature, skeletal anomalies, and neurological defects. We described the clinical features of a Chinese patient with CWC27-related spliceosomeopathy and identified the pathogenic variant.

METHODS

The affected subject underwent detailed ophthalmic examinations. Systemic abnormalities were assessed, including body height, craniofacial morphology, oral cavity, hands, feet, hair and skin. Genomic DNA was isolated from peripheral blood and sequenced by next-generation sequencing. Sanger sequencing was performed for validation and segregation.

RESULTS

The patient had poor vision, nyctalopia and nystagmus from childhood. Fundoscopy revealed extensive chorioretinal atrophy with numerous scattered greyish pigmentation. Severe circular areas of macular atrophy were observed. Optical coherent tomography showed reduced retinal thickness with nearly absent ellipsoid zone and retinal pigment epithelium. In addition, craniofacial abnormalities, short statue, brachydactyly, dental anomalies, cafe-au-lait spots, scant hair, absent eyebrows and thin eyelashes were documented. Genetic analysis revealed a novel homozygous novel small deletion c.1133delG(p.G378Efs*12) in CWC27 (NM_005869.2).

CONCLUSIONS

We present a patient with early-onset retinitis pigmentosa and marked syndromic features. A novel CWC27 pathogenic variant was identified. Our findings broaden the clinical and mutation spectrum of CWC27-related spliceosomeopathy, and could be helpful in diagnosis of this rare disease.

Retinitis pigmentosa with or without skeletal abnormalities due to homozygous mutations in the CWC27 gene: A case report

RATIONALE

Retinitis pigmentosa with or without skeletal abnormalities (RPSKA) is an autosomal recessive disorder caused by mutations in the CWC27 gene. Skeletal dysplasia and non-syndromic retinitis pigmentosa are typical manifestations, and most patients present with retinopathy such as retinitis pigmentosa and limited visual field. Its clinical manifestations are complex and diverse, often involving multiple systems. Examples include short finger deformities, peculiar facial features, short stature, and neurodevelopmental abnormalities, and it is easy to misdiagnose clinically, and early diagnosis is crucial for prognosis.

PATIENT CONCERNS

A 2-year and 2-month-old female child was admitted to the hospital due to "unsteady walking alone and slow reaction for more than half a year." After admission, the child was found to have delayed motor development, accompanied by special face, abnormal physical examination of the nervous system, cranial MRI Dandy-Walker malformation, considering developmental delay.

DIAGNOSES

Whole exome sequencing of the family line revealed the presence of a c.617(exon7)C>A pure mutation in the CWC27 gene in the affected child (this locus has been reported in the clinical literature); the final diagnosis is RPSKA.

INTERVENTIONS

Unfortunately, there is no specific drug for the disease; we give children rehabilitation training treatment.

OUTCOMES

During follow-up process we found that children's condition is better than before.

LESSONS SUBSECTIONS AS PER STYLE

We reported a case of RPSKA caused by mutations in the CWC27 gene. This study adds to our understanding of the clinical phenotype of TBL1XR1 mutations and provides a realistic and reliable basis for clinicians.

Mutations in the Spliceosome Component CWC27 Cause Retinal Degeneration with or without Additional Developmental Anomalies

Pre-mRNA splicing factors play a fundamental role in regulating transcript diversity both temporally and spatially. Genetic defects in several spliceosome components have been linked to a set of non-overlapping spliceosomopathy phenotypes in humans, among which skeletal developmental defects and non-syndromic retinitis pigmentosa (RP) are frequent findings. Here we report that defects in spliceosome-associated protein CWC27 are associated with a spectrum of disease phenotypes ranging from isolated RP to severe syndromic forms. By whole-exome sequencing, recessive protein-truncating mutations in CWC27 were found in seven unrelated families that show a range of clinical phenotypes, including retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects. Remarkably, variable expressivity of the human phenotype can be recapitulated in Cwc27 mutant mouse models, with significant embryonic lethality and severe phenotypes in the complete knockout mice while mice with a partial loss-of-function allele mimic the isolated retinal degeneration phenotype. Our study describes a retinal dystrophy-related phenotype spectrum as well as its genetic etiology and highlights the complexity of the spliceosomal gene network.

New syndrome with retinitis pigmentosa is caused by nonsense mutations in retinol dehydrogenase RDH11

Retinitis pigmentosa (RP), a genetically heterogeneous group of retinopathies that occur in both non-syndromic and syndromic forms, is caused by mutations in ∼100 genes. Although recent advances in next-generation sequencing have aided in the discovery of novel RP genes, a number of the underlying contributing genes and loci remain to be identified. We investigated three siblings, born to asymptomatic parents of Italian-American descent, who each presented with atypical RP with systemic features, including facial dysmorphologies, psychomotor developmental delays recognized since early childhood, learning disabilities and short stature. RP-associated ophthalmological findings included salt-and-pepper retinopathy, attenuation of the arterioles and generalized rod-cone dysfunction as determined by almost extinguished electroretinogram in 2 of 3 siblings. Atypical for RP features included mottled macula at an early age and peripapillary sparing of the retinal pigment epithelium. Whole-exome sequencing data, queried under a recessive model of inheritance, identified compound heterozygous stop mutations, c.C199T:p.R67* and c.C322T:p.R108*, in the retinol dehydrogenase 11 (RDH11) gene, resulting in a non-functional protein, in all affected children. In summary, deleterious mutations in RDH11, an important enzyme for vision-related and systemic retinoic acid metabolism, cause a new syndrome with RP.

Autosomal recessive Oliver-McFarlane syndrome: Retinitis pigmentosa, short stature (GH deficiency), trichomegaly, and hair anomalies or CPD syndrome (chorioretinopathy-pituitary dysfunction)

We describe a brother and sister with retinitis pigmentosa (RP), growth failure, long eyelashes, and sparse hair. They were born to young healthy consanguineous parents and presented at birth with IUGR. Evolving pigmentary retinopathy was diagnosed at the age of 5 years. A similar condition (Oliver-McFarlane) syndrome was reported previously. Our two sibs confirm the existence of this autosomal recessive syndrome.