An association and haplotype analysis of porcine maternal infanticide: a model for human puerperal psychosis?

An association analysis using the Illumina porcine SNP60 beadchip was performed to identify SNPs significantly associated with porcine maternal infanticide. We previously hypothesised that this was a good animal model for human puerperal psychosis, an extreme form of postnatal mood disorder. Animals were selected from carefully phenotyped unrelated infanticide and control groups (representing extremes of the phenotypic spectrum), from four different lines. Permutation and sliding window analyses and an analysis to see which haplotypes were in linkage disequilibrium (LD) were compared to identify concordant regions. Across all analyses, intervals on SSCs 1, 3, 4, 10, and 13 were constant, contained genes associated with psychiatric or neurological disorders and were significant in multiple lines. The strongest (near GWS) consistent candidate region across all analyses and all breeds was the one located on SSC3 with one peak at 23.4 Mb, syntenic to a candidate region for bipolar disorder and another at 31.9 Mb, syntenic to a candidate region for human puerperal psychosis (16p13). From the haplotype/LD analysis, two regions reached genome wide significance (GWS): the first on SSC4 (KHDRBS3 to FAM135B), which was significant (-logP 5.57) in one Duroc based breed and is syntenic to a region in humans associated with cognition and neurotism; the second on SSC15, which was significant (-log10P 5.68) in two breeds and contained PAX3, which is expressed in the brain.

Analysis of X chromosome genomic DNA sequence copy number variation associated with premature ovarian failure (POF).

BACKGROUND: Premature ovarian failure (POF) is a heterogeneous disease defined as amenorrhoea for >6 months before age 40, with an FSH serum level >40 mIU/ml (menopausal levels). While there is a strong genetic association with POF, familial studies have also indicated that idiopathic POF may also be genetically linked. Conventional cytogenetic analyses have identified regions of the X chromosome that are strongly associated with ovarian function, as well as several POF candidate genes. Cryptic chromosome abnormalities that have been missed might be detected by array comparative genomic hybridization. METHODS: In this study, samples from 42 idiopathic POF patients were subjected to a complete end-to-end X/Y chromosome tiling path array to achieve a detailed copy number variation (CNV) analysis of X chromosome involvement in POF. The arrays also contained a 1 Mb autosomal tiling path as a reference control. Quantitative PCR for selected genes contained within the CNVs was used to confirm the majority of the changes detected. The expression pattern of some of these genes in human tissue RNA was examined by reverse transcription (RT)-PCR. RESULTS: A number of CNVs were identified on both Xp and Xq, with several being shared among the POF cases. Some CNVs fall within known polymorphic CNV regions, and others span previously identified POF candidate regions and genes. CONCLUSIONS: The new data reported in this study reveal further discrete X chromosome intervals not previously associated with the disease and therefore implicate new clusters of candidate genes. Further studies will be required to elucidate their involvement in POF.

Analysis of the non-recombining Y chromosome defines polymorphisms in domestic pig breeds: ancestral bases identified by comparative sequencing.

Sequences from 20 amplicons representing nine different loci and 11369bp from the short arm of the pig Y chromosome were compared using pools of DNA from different European and Chinese breeds. A total of 33 polymorphic sites were identified, including five indels and 28 single nucleotide polymorphisms (SNPs). Three high frequency SNPs within the coding regions of SRY were further analysed across 889 males representing 25 European and 25 Asian breeds or Lines, plus a European Line of Meishan. Two haplotypes seen to be associated with 'European' or 'Chinese' origin in the initial SNP discovery phase were found to be the most common in their respective groups of breeds in a more detailed genotyping study. Two further SRY haplotypes are relatively rare. One was found exclusively within Tamworth, at low frequency in Retinto, and in three Chinese breeds (Huai, Sahwutou and Xiaomeishan). The other uncommon haplotype is found exclusively in Bamajiang, two further Chinese breeds (Hangjiang Black and Longling) and two European rare breeds (Mangalica and Linderödssvin), but appears based on comparison with other suids to represent an ancestral sequence.

Chromosomal mapping, sequence and transcription analysis of the porcine fertilin beta gene (ADAM2).

Fertilin beta (ADAM2) forms a part of the heterodimeric surface protein fertilin, found on the plasma membrane of mammalian sperm, and has been implicated in the process of sperm-egg fusion. Analysis of cDNA products obtained from adult porcine testis mRNA has presented a sequence corresponding to 2620 bp of the ADAM2 gene. This sequence contained an open reading frame encoding a 735-amino acid protein and homologous to ADAM2 genes known in other mammalian species. Polymerase chain reaction (PCR) analysis of genomic DNA showed that the 2620 bp of cDNA sequence comprises at least 21 exons and spans approximately 76 kb of genomic DNA, with its size and structure being relatively conserved between mouse, human and pig. Fluorescence in situ hybridization was used to map ADAM2 to chromosome 15 of the pig, using a bacterial artificial chromosome clone from the PigE BAC library. This finding is consistent with comparative mapping experiments performed between pig and human chromosomes. Analysis of nine mRNA samples, by reverse transcriptase-PCR, from different porcine tissues has also suggested that expression of ADAM2 is limited to the testis, a finding that is consistent with other mammalian species.

X/XY/XYY mosaicism as a cause of subfertility in boars: a single case study.

Sex chromosome abnormalities are common in mammals and humans and are often associated with subfertility. In this study a boar with normal sperm parameters was indicated to have reduced prolificacy from figures obtained for return rate, farrowing rate and total number of piglets born. G-banded cytogenetic analysis of peripheral blood identified an abnormal mosaic sex chromosome constitution 39,XYY[74]/38,XY[23]/37,X[3]. Cytogenetic analysis of fibroblasts confirmed this mosaic karyotype with similar percentages of cell lines observed 39,XYY[76]/38,XY[19]/37,X[5]. External genitalia revealed a poorly developed scrotum with the right testicle being smaller than the left. To the best of our knowledge this is the first time that this chromosome constitution has been reported in the pig. It is of particular interest that this karyotype is associated with reduced boar fertility, which could lead to potential economic losses if such a boar were selected for breeding purposes.

Characterization of the porcine sperm adhesion molecule gene SPAM1- expression analysis, genomic structure, and chromosomal mapping.

Sequence analysis of cDNA products, derived from adult porcine testis mRNA, gave overlapping nucleotide sequence correlating to 1952 bp of the sperm adhesion molecule 1 (SPAM1) gene. This sequence was shown to be homologous to SPAM1 genes known in other mammalian species and contained an open reading frame encoding a 493-amino acid protein. Fluorescence in situ hybridization (FISH), using a bacterial artificial chromosome (BAC) clone from the PigE BAC library, was used to map SPAM1 to chromosome 18 of the pig. This finding is consistent with comparative mapping experiments performed between pig and human chromosomes. Polymerase chain reaction (PCR) analysis of genomic DNA has shown that the 1952 bp of cDNA sequence spans approximately 9 kb of genomic DNA and comprises of at least four exons, with its size and structure being relatively conserved between mouse, human and pig. Reverse transcriptase (RT)-PCR analysis of mRNA from nine porcine tissues has also suggested that expression of SPAM1 is limited to the testis.

Aneuploidy screening in direct chorionic villus samples by fluorescence in situ hybridisation: the use of commercial probes in a clinical setting.

The results of screening for the common aneuploidies involving chromosomes 13, 18, 21, X and Y by florescent in-situ hybridisation (FISH) in direct preparations from 100 chorionic villus samples from pregnancies between 10 and 20 weeks' gestation are reported. Samples prepared using routine methods and analysed with commercially available probes, accurately detected 12 cases of fetal aneuploidy, all referred because of developmental abnormality. Three of the four cases where chromosome abnormality was detected in cultured villi but not by the direct fluorescence in situ hybridisation (FISH) assay, were due to confined placental mosaicism. No chromosomal anomalies were found in the 20 low risk cases where the referral reason was a familial single gene disorder. We conclude that the FISH assay with commercial probes may act as an accurate and less labour intensive alternative to direct chromosome analysis of chorionic villus samples. In cytogenetically low risk cases its use can obtain a result within the time needed for DNA analysis and avoid the need to set up cultures.

A familial case of X chromosome deletion ascertained by cytogenetic screening of women with premature ovarian failure.

The association between X chromosome deletions and premature ovarian failure is well established. Previous anecdotal reports however, have not documented the prevalence of X deletions in women with premature ovarian failure. We therefore performed cytogenetic analyses on 79 women with primary or secondary amenorrhoea to assess the utility of screening for a genetic marker for familial premature ovarian failure. A normal karyotype was found in 77 women. One woman with primary amenorrhoea had an XY karyotype and a woman with secondary amenorrhoea had a deletion at Xq 26.1. This second case had a family history of premature ovarian failure, and her mother who underwent premature ovarian failure at 28 years shared this deletion. The early diagnosis of familial X deletions causing premature ovarian failure allowed for the prediction of impending menopause and the implementation of manoeuvres to advance conception. Although cytogenetic aberrations are rare in secondary amenorrhoea, the ability to predict premature ovarian failure can be vital.

Cytogenetic and molecular investigations of Y chromosome sequences and their role in Turner syndrome.

It has been proposed that all live born females with Turner syndrome carry a cell line containing two sex chromosomes, which may be present at a low level of mosaicism (Hook & Warburton, 1983; Hassold et al. 1985; 1988; Connor & Loughlin, 1989). If the second sex chromosome is a Y, these patients are at risk of developing gonadoblastoma. In this study, 50 patients found to have a 45,X karyotype by conventional cytogenetic analysis, were screened by the polymerase chain reaction (PCR), for the presence of Y chromosome sequences. Two patients were positive for six of the eight Y chromosome loci tested and additional cytogenetic analysis confirmed the presence of a marker chromosome, in 8% and 3% of cells respectively. Fluorescence in situ hybridization (FISH) was used to confirm that the markers were of Y chromosome origin and helped to elucidate their structure. In addition, four other patients were found to have a Y chromosome by initial routine cytogenetic analysis. FISH, in conjunction with PCR, elucidated the structure of the Y chromosomes. This study illustrates the value of using a combination of cytogenetic and molecular techniques, to identify Y chromosome sequences in Turner syndrome.