Marinesco-Sjögren syndrome caused by a new SIL1 frameshift mutation

Identification of novel mutations by targeted NGS in Moroccan families clinically diagnosed with a neuromuscular disorder

BACKGROUND AND AIMS

The identification of underlying genes of genetic conditions has expanded greatly in the past decades, which has broadened the field of genes responsible for inherited neuromuscular diseases. We aimed to investigate mutations associated with neuromuscular disorders phenotypes in 2 Moroccan families.

MATERIAL AND METHODS

Next-generation sequencing combined with Sanger sequencing could assist with understanding the hereditary variety and underlying disease mechanisms in these disorders.

RESULTS

Two novel homozygous mutations were described in this study. The SIL1 mutation is the first identified in the Moroccan population, the mutation was identified as the main cause of Marinesco-Sjogren syndrome in one patient. While the second mutation identified in the fatty acid 2-hydroxylase gene (FA2H) was associated with the Spastic paraplegia 35 in another patient, both transmitted in an autosomal recessive pattern.

DISCUSSION AND CONCLUSIONS

These conditions are extremely rare in the North African population and may be underdiagnosed due to overlapping clinical characteristics and heterogeneity of these diseases. We have reported in this study mutations associated with the diseases found in the patients. In addition, we have narrowed the phenotypic spectrum, as well as the diagnostic orientation of patients with neuromuscular disorders, who might have very similar symptoms to other disease groups.

Novel SIL1 nonstop mutation in a Chinese consanguineous family with Marinesco-Sjögren syndrome and Dandy-Walker syndrome

Marinesco-Sjögren syndrome (MSS) is a rare autosomal recessive disorder, which is characterized by congenital cataracts, cerebellar ataxia, progressive muscle weakness, and delayed psychomotor development. SIL1, which is located at 5q31.2, is the only gene known to cause MSS. Dandy-Walker syndrome (DWS) is defined by hypoplasia, upward rotation of the cerebellar vermis, and cystic dilation of the fourth ventricle; however, its genetic pathogeny remains unclear. Here, we report a Chinese consanguineous family with MSS and DWS. Whole exome sequencing identified a novel nonstop mutation in SIL1. Sanger sequencing revealed that the mutation was segregated in this family according to a recessive mode of inheritance. We found that the mutation changed a stop codon (TGA) to an arginine codon (CGA), and no in-frame termination codon in the 3' untranslated region (UTR) of SIL1 could be found. The mRNA levels of SIL1 were decreased by 56.6% and 37.5% in immortalized lymphoblasts of the patients respectively; the protein levels of SIL1 were substantially decreased. This case study is the first report on Chinese MSS patients, MSS complicated by DWS, and a nonstop mutation in SIL1. Our findings imply the pathogenetic association between DWS and MSS.

Eclectic Ocular Comorbidities and Systemic Diseases with Eye Involvement: A Review

Coexistence of several ocular diseases is more frequent than suspected. In spite of the refractive errors, one or more of the following can be detected simultaneously: glaucoma, cataracts, uveitis, age-related macular degeneration, and dry eyes. In addition, as people age, ocular comorbidities are much more usually seen. Specific diseases are openly acknowledged to affect the eyes and vision, such as diabetes mellitus, hypertension blood pressure, arthritis, hyperthyroidism, neurodegenerative disorders, hematologic malignancies, and/or systemic infections. Recent advances in early diagnosis and therapy of the ophthalmic pathologies have reinforced patient options to prevent visual impairment and blindness. Because of this, it is essential not to overlook sight-threatening conditions such as the ocular comorbidities and/or the eye involvement in the context of systemic disorders. Moreover, the important role of the multidisciplinary cooperation to improve and sustain management of patients affected with eclectic ocular comorbidities and/or systemic disorders with eye repercussion is specifically addressed. This review intends to shed light on these topics to help in making opportune diagnosis and appropriately managing the affected patients.