A Family Segregating Lethal Primary Coenzyme Q10 Deficiency Due to Two Novel COQ6 Variants.

Primary coenzyme Q10 deficiency-6 (COQ10D6), as a rare autosomal recessive disease caused by COQ6 mutations, is characterized by progressive infantile-onset nephrotic syndrome resulting in end-stage renal failure and sensorineural hearing loss. Here, we report two Chinese siblings with COQ10D6 who primarily presented with severe metabolic acidosis, proteinuria, hypoalbuminemia, growth retardation, and muscle hypotonia and died in early infancy. Using whole-exome sequencing and Sanger sequencing, we identified two rare recessive nonsense mutations in the COQ6 gene segregating with disease in affected family members: c.249C > G (p.Tyr83Ter) and c.1381C > T (p.Gln461Ter), resulting in two truncated protein products. Both mutations are located in a highly conserved area and are predicted to be pathogenic. Indeed, the death of our patients in early infancy indicates the pathogenicity of the p.Tyr83Ter and p.Gln461Ter variants and highlights the significance of the two variants for COQ6 enzyme function, which is necessary for the biosynthesis of coenzyme Q10. In conclusion, we discovered a novel compound heterozygous pathogenic variant of the COQ6 gene as a cause of severe COQ10D6 in the two siblings. Based on the clinical history and genetic characteristics of the patients, our cases expand the genotypic spectrum of COQ10D6 and highlight the heterogeneity and severity of clinical features associated with COQ6 mutations. For patients with clinical manifestations suggestive of COQ10D6, early testing for COQ6 mutations is beneficial for disease diagnosis and therapeutic interventions as well as disease prevention in future generations.

A new genotype imputation method with tolerance to high missing rate and rare variants.

We report a novel algorithm, iBLUP, to impute missing genotypes by simultaneously and comprehensively using identity by descent and linkage disequilibrium information. The simulation studies showed that the algorithm exhibited drastically tolerance to high missing rate, especially for rare variants than other common imputation methods, e.g. BEAGLE and fastPHASE. At a missing rate of 70%, the accuracy of BEAGLE and fastPHASE dropped to 0.82 and 0.74 respectively while iBLUP retained an accuracy of 0.95. For minor allele, the accuracy of BEAGLE and fastPHASE decreased to -0.1 and 0.03, while iBLUP still had an accuracy of 0.61.We implemented the algorithm in a publicly available software package also named iBLUP. The application of iBLUP for processing real sequencing data in an outbred pig population was demonstrated.

Genome-wide association studies for growth and meat production traits in sheep.

BACKGROUND: Growth and meat production traits are significant economic traits in sheep. The aim of the study is to identify candidate genes affecting growth and meat production traits at genome level with high throughput single nucleotide polymorphisms (SNP) genotyping technologies. METHODOLOGY AND RESULTS: Using Illumina OvineSNP50 BeadChip, we performed a GWA study in 329 purebred sheep for 11 growth and meat production traits (birth weight, weaning weight, 6-month weight, eye muscle area, fat thickness, pre-weaning gain, post-weaning gain, daily weight gain, height at withers, chest girth, and shin circumference). After quality control, 319 sheep and 48,198 SNPs were analyzed by TASSEL program in a mixed linear model (MLM). 36 significant SNPs were identified for 7 traits, and 10 of them reached genome-wise significance level for post-weaning gain. Gene annotation was implemented with the latest sheep genome Ovis_aries_v3.1 (released October 2012). More than one-third SNPs (14 out of 36) were located within ovine genes, others were located close to ovine genes (878bp-398,165bp apart). The strongest new finding is 5 genes were thought to be the most crucial candidate genes associated with post-weaning gain: s58995.1 was located within the ovine genes MEF2B and RFXANK, OAR3_84073899.1, OAR3_115712045.1 and OAR9_91721507.1 were located within CAMKMT, TRHDE, and RIPK2 respectively. GRM1, POL, MBD5, UBR2, RPL7 and SMC2 were thought to be the important candidate genes affecting post-weaning gain too. Additionally, 25 genes at chromosome-wise significance level were also forecasted to be the promising genes that influencing sheep growth and meat production traits. CONCLUSIONS: The results will contribute to the similar studies and facilitate the potential utilization of genes involved in growth and meat production traits in sheep in future.

Genotyping by genome reducing and sequencing for outbred animals.

Next-generation sequencing (NGS) approaches are widely used in genome-wide genetic marker discovery and genotyping. However, current NGS approaches are not easy to apply to general outbred populations (human and some major farm animals) for SNP identification because of the high level of heterogeneity and phase ambiguity in the haplotype. Here, we reported a new method for SNP genotyping, called genotyping by genome reducing and sequencing (GGRS) to genotype outbred species. Through an improved procedure for library preparation and a marker discovery and genotyping pipeline, the GGRS approach can genotype outbred species cost-effectively and high-reproducibly. We also evaluated the efficiency and accuracy of our approach for high-density SNP discovery and genotyping in a large genome pig species (2.8 Gb), for which more than 70,000 single nucleotide polymorphisms (SNPs) can be identified for an expenditure of only $80 (USD)/sample.

[Genetic diversity and origin of mitochondria DNA D-loop region of some Chinese indigenous cattle breeds].

The complete D-loop region of mitochondrial DNA from 206 individuals in 16 Chinese indigenous cattle breeds was sequenced and analyzed to detect variability of D-loop region of mitochondria DNA for those breeds. The results showed as follows: 101 variations and 99 haplotypes were found, in which 73 haplotypes were of Bos taurus and the other 26 haplotypes were of Bos indicus, and the average number of nucleotide differences was 22.6920, haplotype diversity was 0.9320, and nucleotide diversity was 0.0227, indicating high genetic diversity in Chinese indigenous cattle breeds. According to the NJ phylogenetic tree, 16 cattle breeds were divided into two clades, Bos taurus and Bos indicus. Based on the Network graphics, the 73 haplotypes of Bos taurus were classified into 3 groups and the 26 haplotypes of Bos indicus were classified into 5 groups. It was inferred that cattle breeds of Bos indicus in China had experienced at least 4 population expansions during their movement. There was only 16% of H3 haplotype sequences similar to the sequence of Nellore, and 84% of those sequences had purine C variation in Chinese indigenous cattle breeds through the analysis on their common H3 haplotypes. It was concluded that those purine C decrease was possibly originated in Chinese Bos indicus.

[Genetic variation of A-FABP microsatellites in eleven pig breeds].

The genetic variations of microsatellites in intron 2 of the porcine adipocyte fatty acid-binding protein (A-FABP) genes were investigated in 420 pigs including Wuzhishan pig, Yimeng black pig, Hanjiang black pig, Laiwu pig, Beijing black pig, Min pig, Chenghua pig, Neijiang pig, Erhualian pig, Bama xiang pig and Large White pig. The results suggested as follows: (i)PIC of the Wuzhishan pig breed is the highest (0.7904) and 11 alleles were detected. Compared with Large White pig,Chinese pig breeds showed a great polymorphism of A-FABP microsatellites except Beijing black pig in which only 2 alleles were detected. (ii) Only Min pig, Bama xiang pig, Beijing black pig and Large White pig were in Hardy-Weinberg equilibrium. (iii) The analysis of genetic differentiation showed that the average value of the A-FABP gene differentiation of 10 Chinese pigs is about 40.83%.

[Sequence analysis of polymorphic fragments of porcine H-FABP gene].

Three variant restriction sites of porcine H-FABP gene,including HinfI-RFLP in 5'-upstream, HaeIII-RFLP and HinfI*-RFLP in intron 2, were confirmed by PCR-RFLP method. The polymorphic fragments were cloned and sequenced. The results revealed a single nucleotide substitution of T-->C at position 1324 for HinfI-RFLP,C-->G at position 1811 for HaeIII-RFLP and T-->C at position 1970 for HinfI*-RFLP, respectively.