Genetic alterations are a major cause of microphthalmos, while novel-related genes and mutations in microphthalmos have rarely been explored. To identify the underlying genetic defect responsible for microphthalmos eyes in two three-generation Chinese families, we screened 425 genes involved in common inherited non-syndromic eye diseases with next-generation sequencing-based target capture sequencing of the two probands of two three-generation Chinese families diagnosed with microphthalmos. Variants were filtered and analyzed to identify possible disease-causing variants before Sanger sequencing validation. We enrolled two families with microphthalmos (Family 1: microphthalmos with congenital ocular coloboma and Family 2: simple microphthalmos). Two novel heterozygous mutations, Peroxidasin (PXDN) c.3165C>T (p.Pro1055Pro) and PXDN c.2640C>G (p.Arg880Arg), were found in Family 1, and Crystallin Beta B2 (CRYBB2) c.481G>A (p.Gly161Arg) was found in Family 2, but none of the mutations were found in the unaffected individuals, who were phenotypically normal. Multiple orthologous sequence alignment (MSA) revealed that the CRYBB2 p.Gly161Arg mutation was a deleterious effect mutation. In conclusion, the three novel mutations found in our study extend our current understanding of the genetic basis of microphthalmos and provide early pre-symptomatic diagnosis and emphasize the significance of genetic diagnosis of microphthalmos.

Purpose: To broaden the mutation and phenotype spectrum of the GJA8 and CHMP4B genes and to reveal genotype-phenotype correlations in a cohort of Chinese patients with congenital cataracts (CCs). Methods: Six Chinese Han families with CCs inherited in an autosomal dominant (AD) pattern were recruited for this study. All patients underwent full ocular examinations. Genomic DNA was extracted from the leukocytes of peripheral blood collected from all available patients and their unaffected family members. Whole-exome sequencing (WES) was performed on all probands and at least one of their parents. Candidate variants were further confirmed by Sanger sequencing. Bioinformatic analysis with several computational predictive programs was performed to assess the impacts of the candidate variants on the structure and function of the proteins. Results: Four heterozygous candidate variants in three different genes (CRYBB2, GJA8, and CHMP4B) were identified in affected individuals from the six families, including two novel missense variants (GJA8: c.64G > C/p. G22R, and CHMP4B: c.587C > G/p. S196C), one missense mutation (CRYBB2: c.562C > T/p. R188C), and one small deletion (GJA8: c.426_440delGCTGGAGGGGACCCT/p.143_147delLEGTL). The three missense mutations were predicted as deleterious in all four computational prediction programs. In the homologous model, the GJA8: p.143_147delLEGTL mutation showed a sequence deletion of five amino acids at the cytoplasmic loop of the Cx50 protein, close to the third transmembrane domain. Patients carrying mutations in the same gene showed similar cataract phenotypes at a young age, including total cataracts, Y-sutural with fetal nuclear cataracts, and subcapsular cataracts. Conclusion: This study further expands the mutation spectrum and genotype-phenotype correlation of CRYBB2, GJA8, and CHMP4B underlying CCs. This study sheds light on the importance of comparing congenital cataract phenotypes in patients at the same age stage. It offers clues for the pathogenesis of CCs and allows for an early prenatal diagnosis for families carrying these genetic variants.

Congenital cataracts is the most common cause of visual impairment and blindness in children. Although there have been extensive studies into the pathogenesis of congenital cataracts, the pathogenic mechanism underlying the recurrent variant CRYBB2:c.62T>A(p.I21N) has not been previously reported. Thus, the present study aimed to use whole-exome sequencing (WES) to identify potential genetic variants and investigate how they may have induced the occurrence of cataracts in a four-generation Chinese family with congenital nuclear cataracts. The medical history of this family was recorded and WES was conducted for one proband. Sanger sequencing was used to verify the presence of the putative variant in all participants. PolyPhen-2, SIFT and ProtScale were used to analyze the effect of the identified variants on protein function and hydrophobicity, and Pymol was used to show the structure of the wild-type (Wt) and mutant β-crystallin B2 (CRYBB2) protein. Full-length Wt-CRYBB2 or mutant-CRYBB2 (I21N-CRYBB2) were fused to green fluorescent protein (GFP), and the recombinant plasmids were transfected into HeLa cells. Reverse transcription-quantitative PCR and western blotting were used to detect the expression levels of CRYBB2 mRNA and protein. Immunofluorescence and flow cytometry analyses were used to detect protein localization and apoptosis, respectively. A recurrent variant CRYBB2:c.62T>A(p.I21N) was identified in a four-generation Chinese family with congenital nuclear cataracts. Multiple-sequence alignment of CRYBB2 demonstrated that codon 21 was highly conserved. Pymol revealed that the structure of the I21N-CRYBB2 protein was distinct from that of Wt-CRYBB2. PolyPhen-2 predicted that it had a variant provean score 1.0, suggesting it was \'probably damaging\', and SIFT predicted it had a variant provean score of -5.113, indicating it was \'deleterious\'. ProtScale indicated that the hydrophobicity of the mutation site was significantly reduced. The protein expression levels of the I21N-CRYBB2 were decreased compared with the Wt-CRYBB2. Immunofluorescence analysis revealed that the variant I21N-CRYBB2 protein tended to accumulate around the nucleus, and flow cytometry analysis indicated that it increased cell apoptosis. Furthermore, I21N-CRYBB2 induced the activation of the unfolded protein response (UPR). In conclusion, a pathogenic variant of CRYBB2:c.62T>A(p.I21N) was identified via WES in a four-generation Chinese family with congenital nuclear cataracts. Through biological analysis, it was found that the variant induced abnormal protein aggregation, activated the UPR and triggered excessive cell apoptosis, which may lead to the occurrence of congenital nuclear cataracts in this family.

OBJECTIVE: To summarize the phenotypes and identify the underlying genetic cause of the CRYBB1 and CRYBB2 gene responsible for congenital cataract in two Chinese families.
METHODS: Detailed family histories and clinical data were collected from patients during an ophthalmologic examination. Of 523 inheritable genetic vision system-related genes were captured and sequenced by targeted next-generation sequencing, and the results were confirmed by Sanger sequencing. The possible functional impacts of an amino acid substitution were performed with PolyPhen-2 and SIFT predictions.
RESULTS: The patients in the two families were affected with congenital cataract. Sixty-five (FAMILY-1) and sixty-two (FAMILY-2) single-nucleotide polymorphisms and indels were selected by recommended filtering criteria. Segregation was then analyzed by applying Sanger sequencing with the family members. A heterozygous CRYBB1 mutation in exon 4 (c.347T>C, p.L116P) was identified in sixteen patients in FAMILY-1. A heterozygous CRYBB2 mutation in exon 5 (c.355G>A, p.G119R) was identified in three patients in FAMILY-2. Each mutation co-segregated with the affected individuals and did not exist in unaffected family members and 200 unrelated normal controls. The mutation was predicted to be highly conservative and to be deleterious by both PolyPhen-2 and SIFT.
CONCLUSIONS: The CRYBB1 mutation (c.347T>C) and CRYBB2 mutation (c.355G>A) are novel in patients with congenital cataract. We summarize the variable phenotypes among the patients, which expanded the phenotypic spectrum of congenital cataract in a different ethnic background.

As part of the βγ-superfamily, βB2-crystallin (CRYBB2) is an ocular structural protein in the lens, and mutation of the corresponding gene can cause cataracts. CRYBB2 also is expressed in non-lens tissue such as the adult mouse brain and is associated with neuropsychiatric disorders such as schizophrenia. Nevertheless, the robustness of this association as well as how CRYBB2 may contribute to disease-relevant phenotypes is unknown. To add further clarity to this issue, we performed a comprehensive analysis of behavioral and neurohistological alterations in mice with an allelic series of mutations in the C-terminal end of the Crybb2 gene. Behavioral phenotyping of these three βB2-mutant lines Crybb2O377, Crybb2Philly, and Crybb2Aey2 included assessment of exploratory activity and anxiety-related behavior in the open field, sensorimotor gating measured by prepulse inhibition (PPI) of the acoustic startle reflex, cognitive performance measured by social discrimination, and spontaneous alternation in the Y-maze. In each mutant line, we also quantified the number of parvalbumin-positive (PV+) GABAergic interneurons in selected brain regions that express CRYBB2. While there were allele-specific differences in individual behaviors and affected brain areas, all three mutant lines exhibited consistent alterations in PPI that paralleled alterations in the PV+ cell number in the thalamic reticular nucleus (TRN). The direction of the PPI change mirrored that of the TRN PV+ cell number thereby suggesting a role for TRN PV+ cell number in modulating PPI. Moreover, as both altered PPI and PV+ cell number are schizophrenia-associated endophenotypes, our result implicates mutated Crybb2 in the development of this neuropsychiatric disorder.

Dendrite morphogenesis is a complex but well-orchestrated process. Various studies reported the involvement of alteration in dendrite morphology in different brain disorders, including neuropsychiatric disorders. Initially, βB2-crystallin (gene symbol: Crybb2/CRYBB2) has been described as a structural protein of the ocular lens. Mutations of the corresponding gene, Crybb2, lead to cataract. Recent studies in mice suggested that mutations in Crybb2 cause alterations in hippocampal morphology and function, albeit its function in hippocampal neuron development remained elusive. In the current study, we found that Crybb2 contributes to dendritogenesis in vitro and in vivo. Furthermore, screening of previous data on differential expression-arrays, we found Tmsb4X up-regulated in Crybb2 mutants mouse brain. Additionally, Tmsb4X was co-expressed with Crybb2 at actin-enriched cell ruffles. Over-expression of Tmsb4X in cultured hippocampal neurons inhibited dendritogenesis, which phenocopied Crybb2 knock-down. The current study uncovers a new function of Crybb2 in brain development, especially in dendritogenesis, and the possible interplay partner Tmsb4X involved in this process.

Congenital cataract, an important cause of reversible blindness, is due to several causes including Mendelian inheritance. Thirty percent of cataracts are hereditary with participation of the gamma crystallin genes. Clinical and genetic heterogeneity is observed in patients with gene mutations and congenital cataract; about 40 genetic loci have been associated with hereditary cataract. In this study, we identified the underlying genetic cause of an autosomal dominant pulverulent cataract (ADPC) in a large Mexican family. Twenty-one affected patients and 20 healthy members of a family with ADPC were included. Genomic DNA was analyzed by whole exome sequencing in the proband, a normal daughter, and in an affected son, whereas DNA Sanger sequencing was performed in all members of the family. After the bioinformatics analysis, all samples were genotyped using Sanger sequencing to eliminate variants that do not cosegregate with the cataract. We observed a perfect cosegregation of a nonsense mutation c.475C>T (p.Q155*) in exon 6 of the CRYBB2 gene with ADPC. We calculated a logarithm of the odds score of 5.5. This mutation was not detected in healthy members of the family and in 100 normal controls. This is the first Mexican family with ADPC associated with a p.Q155* mutation. Interestingly, this specific mutation in the CRYBB2 gene seems to be exclusively associated with pulverulent/cerulean cataract (with some clinical variability) independent of the population\'s genetic background.

We observed bilateral cataracts on second trimester ultrasound, in two consecutive pregnancies, with no other structural defects detected. The parents were unrelated and had no family history for the disease. The first pregnancy was terminated in week 22. Copy number variation analysis revealed, in both the aborted fetus and the mother, a 495 kb duplication at 22q11.23 encompassing CRYBB3 and CRYBB2, and not present in variation databases. In the second pregnancy, lens hyperechogenicity was detected by ultrasound at week 13 and 4 days. The identical duplication at 22q11.23 was found in the fetus and considered as possibly pathogenic. At weeks 22 and 30, smaller orbit measurements were elucidated on ultrasound, raising concerns as to the underlying molecular genetic cause, necessitating further investigation. Whole-exome sequencing, using DNA of the first fetus, was performed shortly after the birth of a male child, and two truncating RAB3GAP1 mutations were detected: c.538G>T; p. (Glu180*) and c.943C>T; p. (Arg315*). Neither mutation has been previously reported to be disease-causing; however, evaluation in the context of previously published literature indicated their deleterious nature, implying a clinical diagnosis of Warburg micro syndrome or Martsolf syndrome. Sanger sequencing confirmed segregation of the two mutations within the family, consistent with autosomal recessive inheritance. The child born from the second pregnancy showed features typical of Warburg micro syndrome, with the exception of microcephaly, at age 31 months. © 2016 Wiley Periodicals, Inc.

OBJECTIVE: Prostate cancer (PCa) shows disproportionately higher incidence and disease-associated mortality in African Americans. The human crystallin beta B2 (CRYBB2) gene has been reported as one tumor signature gene differentially expressed between African American and European American cancer patients. We investigated the role of CRYBB2 genetic variants in PCa in African Americans.
METHODS: Subjects comprised of 233 PCa cases and 294 controls. Nine haplotype-tagged single nucleotide polymorphisms (SNPs) in and around the CRYBB2 gene were genotyped by pyrosequencing. Association analyses were performed for PCa with adjustment for age and prostate-specific antigen (PSA), under an additive genetic model.
RESULTS: Out of the nine SNPs examined, rs9608380 was found to be nominally associated with PCa (odds ratio (OR)=2.619 (95% confidence interval (CI)=1.156-5.935), p=0.021). rs9306412 was in strong linkage disequilibrium with rs9608380 that showed an association p-value of 0.077. Using ENCODE data, we found rs9608380 mapped to a region annotated with regulatory motifs, such as DNase hypersensitive sites and histone modifications.
CONCLUSIONS: This is the first study to analyze the association between genetic variations in the CRYBB2 gene with PCa. rs9608380, associated with PCa, is a potentially functional variant.

OBJECTIVE: To describe at molecular level a family with pulverulent congenital cataract associated with a CRYGC gene mutation.
METHODS: One family with several affected members with pulverulent congenital cataract and 230 healthy controls were examined. Genomic DNA from leukocytes was isolated to analyze the CRYGA-D cluster, CX46, CX50 and MIP genes through high-resolution melting curve and DNA sequencing.
RESULTS: DNA sequencing in the affected members revealed the c.143G>A mutation (p.R48H) in exon 2 of the CRYGC gene; 230 healthy controls and ten healthy relatives were also analyzed and none of them showed the c.143G>A mutation. No other polymorphisms or mutations were found to be present.
CONCLUSIONS: In the present study, we described a family with pulverulent congenital cataract that segregated the c.143G>A mutation (p.R48H) in the CRYGC gene. A few mutations have been described in the CRYGC gene in autosomal dominant cataract, none of them with pulverulent cataract making clear the clinical heterogeneity of congenital cataract. This mutation has been associated with the phenotype of congenital cataract but also is considered an SNP in the NCBI data base. Our data and previous report suggest that p.R48H could be a disease-causing mutation and not an SNP.