Identification of a novel missense mutation of MIP in a Chinese family with congenital cataracts by target region capture sequencing

Abstract

Congenital cataract is both clinically diverse and genetically heterogeneous. To investigate the underlying genetic defect in three-generations of a Chinese family with autosomal dominant congenital cataracts, we recruited family members who underwent comprehensive ophthalmic examinations. A heterozygous missense mutation c.634G > C (p.G212R) substitution was identified in the MIP gene through target region capture sequencing. The prediction results of PolyPhen-2 and SIFT indicated that this mutation was likely to damage the structure and function of MIP. Confocal microscopy images showed that the intensity of the green fluorescent signal revealed much weaker signal from the mutant compared to the wild-type MIP. The expressed G212R-MIP was diminished and almost exclusively cytoplasmic in the HeLa cells; whereas the WT-MIP was stable dispersed throughout the cytoplasm, and it appeared to be in the membrane structure. Western blot analysis indicated that the protein expression level of the mutant form of MIP was remarkably reduced compared with that of the wild type, however, the mRNA levels of the wild-type and mutant cells were comparable. In conclusion, our study presented genetic and functional evidence for a novel MIP mutation of G212R, which leads to congenital progressive cortical punctate with or without Y suture.

Identification of a novel MIP frameshift mutation associated with congenital cataract in a Chinese family by whole-exome sequencing and functional analysis

“…Moreover, confocal laser scanning immunofluorescence images indicated that WT-MIP protein was observed at the plasma membrane, which is consistent with the distribution of membrane proteins in cells. However, most of the K228fs-MIP protein was observed in the cytoplasm, which is similar to previously reported studies [ 9 – 11 , 22 ]. The site at MIP Ser235 is required for proper MIP translocation to the plasma membrane by PKC-dependent phosphorylation [ 31 ].…”

“…We suggest that this mutation caused the cataract phenotype in this family. To date, approximately 22 mutations have been identified in the MIP gene that are associated with a cataract phenotype: 16 missense/nonsense mutations [ 9 – 11 , 13 – 22 ], 2 splicing variants [ 23 , 24 ], 2 small deletions [ 25 , 26 ] and 2 small insertions [ 12 , 27 ].…”

“…In this study, we detected a decrease in mRNA transcription in mutants using RT-qPCR and lower expression of K228fs-MIP protein than of WT-MIP protein by western blotting after the HA-WT- MIP and HA-K228fs- MIP vectors were individually transfected into HeLa cells. Several other mutations, such as p.G165D [ 9 ], p.Y219X [ 10 ], p.G212R [ 11 ], p.E134G [ 13 ], p.D150H [ 22 ], and p.G213Vfs [ 26 ], have been functionally characterized in vitro. All the above results indicated that the mutation generated unstable or variant proteins.…”

Embryonic Surface Ectoderm-specific Mitofusin 2 Conditional Knockout Induces Congenital Cataracts in Mice

“…About 20,000 to 40,000 new cases of bilateral congenital cataracts are diagnosed each year worldwide. Approximately 70% of the congenital cataracts involve the lens alone 18 . Hereditary cataracts account for a large portion of congenital cataracts.…”

Arrhythmogenic cardiomyopathy: Identification of desmosomal gene variations and desmosomal protein expression in variation carriers

“…Genomic DNA from the cohort of 23 patients with AC was extracted from the myocardial tissue samples using a QIAamp DNA Mini kit (Qiagen China Co., Ltd., Shanghai, China). The DNA sequence of these patients was screened by target capture sequencing, then verified by Sanger sequencing ( 14 , 15 ). All coding exons of the desmosomal genes (DSG2, NM_001943.3, DSC2, NM_024422.3, JUP, NM_021991.2, PKP2, NM_004572.3 and DSP, NM_004415.2) were enriched using custom-made SureSelectXT Target Enrichment arrays (Agilent Technologies, Inc., Santa Clara, CA, USA).…”