A rapid non-enzymatic method for the preparation of HMW DNA from blood for RFLP studies

A linkage between DNA markers on the X chromosome and male sexual orientation

The role of genetics in male sexual orientation was investigated by pedigree and linkage analyses on 114 families of homosexual men. Increased rates of same-sex orientation were found in the maternal uncles and male cousins of these subjects, but not in their fathers or paternal relatives, suggesting the possibility of sex-linked transmission in a portion of the population. DNA linkage analysis of a selected group of 40 families in which there were two gay brothers and no indication of nonmaternal transmission revealed a correlation between homosexual orientation and the inheritance of polymorphic markers on the X chromosome in approximately 64 percent of the sib-pairs tested. The linkage to markers on Xq28, the subtelomeric region of the long arm of the sex chromosome, had a multipoint lod score of 4.0 (P = 10(-5), indicating a statistical confidence level of more than 99 percent that at least one subtype of male sexual orientation is genetically influenced.

Production and characterization of human proliferative T-cell clones specific for human papillomavirus type 1 E4 protein

Human papillomavirus type 1 (HPV1) virions and E4 protein purified from cutaneous warts were tested in lymphocyte proliferation assays using normal individuals. Both antigens were found to be capable of eliciting good lymphoproliferative responses. Several T-cell clones specific for wart E4 protein were obtained from a donor who had consistently responded very well to E4 in these initial assays. They were maintained in culture by repeated stimulation with antigen and interleukin-2, using an autologous mitomycin-treated lymphoblastoid cell line as a source of antigen-presenting cells. Two of these clones (3F5 and 4A8), which behaved identically, have been studied in more detail. A series of overlapping synthetic peptides covering the entire E1 E4 protein sequence was used to identify a single T-cell epitope which maps to a strongly hydrophilic region spanning amino acid residues 38 to 50. We have also tested the ability of a panel of major histocompatibility complex class II-matched and -mismatched lymphoblastoid cell lines to present this peptide to the T-cell clones in proliferation assays. The study reports that the epitope is restricted through HLA-DQ7 and that it can be recognized by T cells with different T-cell receptor gene rearrangements.

A non-organic and non-enzymatic extraction method gives higher yields of genomic DNA from whole-blood samples than do nine other methods tested

We compared ten methods for extraction of DNA from whole blood. Nine methods require incubation with either enzymes or treatment of organic solvents or both. The 'Rapid Method' (RM) (Method 10) avoids the use of organic solvents (phenol/chloroform) and eliminates completely the use of proteinase K. Thus, the time and cost of DNA extraction are reduced significantly. This is accomplished by salting out and precipitation of the cellular proteins in saturated sodium chloride. This method takes less than an hour to completion, without compromising the yield or the quality of DNA. Using RM, we can make DNA from 0.1 ml of whole blood and as little as 0.5 ml of blood yields DNA sufficient to run a few Southern blots. The RM can also be applied to packed cells. The DNA is free of RNA, protein and degrading enzymes. The uncut DNA runs as a typical slow-migrating, high-molecular-weight and undegraded species in an agarose gel. The DNA is suitable for digestion by various restriction endonucleases. This procedure works equally well with fresh blood samples and with those that are stored at 4 degrees C and -70 degrees C. To our knowledge the RM reported here is the safest, fastest and most quantitative and economical method for preparation of DNA from whole blood and cells.

ARMS test for diagnosis of factor VLeiden mutation, a common cause of inherited thrombotic tendency

We developed a simple and rapid amplification-refractory mutation system (ARMS) assay for the factor V mutation [R506Q] (factor VLeiden), which results in the autosomal dominant thrombotic tendency, resistance to activated protein C (rAPC). PCR primers within Exon 10 of the factor V gene were designed. A common upstream primer was paired with either a mutant or wild-type-specific downstream primer. The 3'-most nucleotide of the specific primers recognized either the mutant or normal allele, and the 3' penultimate nucleotide was mismatched to enhance specificity of the reaction. The assay was validated using authentic factor VLeiden DNA samples. Seven of 103 hematologically normal children (6.8%) were found to be heterozygotes. Among 27 patients studied by the rAPC assay, ARMS assay and rAPC results were concordant in 26. Among these were a 1-year-old child with a calcified clot in the inferior vena cava. Both the patient and his father were heterozygous for the mutation and both had abnormal rAPC assays. rAPC and factor VLeiden assays were discordant in a young girl with a history of stroke. Biochemical rAPC assay was abnormal, while ARMS assay revealed amplification only with wild-type primers, suggesting a non-[R506Q] mechanism for rAPC. This assay will be a valuable tool for studying subjects with thromboses and their family members.