A DNA probe for the LDL receptor gene is tightly linked to hypercholesterolemia in a pedigree with early coronary disease.

A large, multigenerational family with dominantly inherited hypercholesterolemia was analyzed for genetic linkage between blood levels of low-density lipoprotein (LDL) cholesterol and the locus for the LDL receptor. A genetic marker was identified by restriction fragment length polymorphism (RFLP) in a cloned segment of the LDL receptor gene. We found no exceptions to segregation of the high-LDL cholesterol phenotype with a unique allele at the LDL receptor locus in this pedigree; tight linkage was indicated by a maximum lod score of 7.

Tetraploid partial hydatidiform moles: two cases with a triple paternal contribution and a 92,XXXY karyotype.

In the course of a systematic study of cytogenetics, morphology, and clinical follow-up of hydatidiform moles we encountered two unusual cases of partial hydatidiform moles each with a 92,XXXY karyotype. Previously reported cases of tetraploidy, of 92,XXXX or 92,XXYY karyotype, resulted from a failure of the first mitotic division of a normal zygote. This is to our knowledge the first report of tetraploidy with XXXY sex chromosomes.

A closely linked genetic marker for cystic fibrosis.

Cystic fibrosis is a recessive genetic disorder, characterized clinically by chronic obstructive lung disease, pancreatic insufficiency and elevated sweat electrolytes; affected individuals rarely live past their early twenties. Cystic fibrosis is also one of the most common genetic diseases in the northern European population. The frequency of carriers of mutant alleles in some populations is estimated to be as high as 1 in 20, carrying a concomitant burden of about one affected child in 1,500 births.

Determination of the parental origin of sex-chromosome monosomy using restriction fragment length polymorphisms.

The parental origin of the single X chromosome in sex-chromosome monosomy was evaluated by comparing restriction fragment length polymorphisms (RFLPs) of 10 spontaneous aborted 45,X conceptions with those of their parents. Seven X-linked marker loci were used, and we were able to specify the origin of the X in nine cases, with six being maternally and three paternally derived. These results demonstrate the efficiency of the technique and show that the single X chromosome in 45,X spontaneous abortions can be derived from either parent.

Construction of linkage maps with DNA markers for human chromosomes.

DNA markers and sampling of three-generation families can be used to construct complete linkage maps of human chromosomes. This is important in mapping disease loci and in determining the genetic or environmental component of a disease.

Interaction of VSV leader RNA and nucleocapsid protein may control VSV genome replication.

The discovery of plus- and minus-strand leader RNAs (short RNAs that are the complement of the exact 3' ends of the viral minus-strand genome and plus-strand antigenome) in VSV-infected cells has led to a model of genome replication in which the viral nucleocapsid protein acts as a modulator of genome transcription and replication. In this model, the VSV leader RNAs are the result of chain termination at an attenuation signal located approximately 50 nucleotides in from the 3' ends of the genome templates. The viral N protein is thought to modulate transcription and replication by its ability to bind to the nascent leader RNA and simultaneously promote read-through of the termination signal and initiate nucleocapsid assembly on the nascent RNA chain.

Effect of defective interfering particles on plus- and minus- strand leader RNAs in vesicular stomatitis virus-infected cells.

Vesicular stomatitis virus-infected cells contain short RNA transcripts, called leader RNAs, which are coded by the exact 3' end of both the minus-strand and plus-strand nucleocapsid templates. The molar amounts of both the plus-strand leader RNA (which is templated from the minus-strand genome) and the minus-strand leader RNA (which is templated from the plus-strand antigenome) were determined both in standard-virus- and mixed-virus-infected cells by using end-labeled genome probes. The results demonstrate that the presence of defective interfering particles in the infecting virus stock decreases the amount of plus-strand leader RNA but increases the amount of minus-strand leader RNA found in the infected cells.

Plus and minus strand leader RNAs in negative strand virus-infected cells.

Sendai virus and VSV minus strand genome RNAs, labeled specifically at their 3' ends with RNA ligase, were used as probes to detect leader RNA--that is, short transcripts (approximately 50 nucleotides) complementary to the exact 3' end of the minus strand genome. These probes have allowed the detection of plus strand leader RNAs in both Sendai virus and VSV-infected cells as well as in the virion transcriptase reactions. The use of a similar probe, prepared from the self-complementary ends of DI genome RNA and containing the 3' end of the plus strand antigenome RNA, has allowed the detection of a minus strand leader RNA of identical size in VSV-infected cells.

5' Terminus of defective and nondefective Sendai viral genomes is ppp Ap.

Using RNase T2 digestion of 32P-labeled Sendai virus nondefective and defective-interfering RNAs, the 5' termini were isolated and demonstrated to be pppAp for both the plus and minus strands.

Further characterization of Sendai virus DI-RNAs: a model for their generation.

Sendai virus DI-RNAs which contain complementary ends have been characterized as follows. First, the complementary ends of three DI-RNAs, although somewhat different in size (110-150 base pairs), contain sequences that are both identical to each other and to the 5' end of the nondefective (ND) genome. Second, almost all the sequences contained sequences that are both identical to each other and to the 5' end of the nondefective (ND) genome.