A search for linkage in cystic fibrosis

Timelines of translational science: From technology initiation to FDA approval

While timelines for clinical development have been extensively studied, there is little data on the broader path from initiation of research on novel drug targets, to approval of drugs based on this research. We examined timelines of translational science for 138 drugs and biologicals approved by the FDA from 2010-2014 using an analytical model of technology maturation. Research on targets for 102 products exhibited a characteristic (S-curve) maturation pattern with exponential growth between statistically defined technology initiation and established points. The median initiation was 1974, with a median of 25 years to the established point, 28 years to first clinical trials, and 36 years to FDA approval. No products were approved before the established point, and development timelines were significantly longer when the clinical trials began before this point (11.5 vs 8.5 years, p<0.0005). Technological maturation represents the longest stage of translation, and significantly impacts the efficiency of drug development.

Absence of an association between HLA typing in cystic fibrosis arthritis and hypertrophic osteoarthropathy

Fourteen patients with cystic fibrosis arthritis and eight patients with cystic fibrosis and hypertrophic osteoarthropathy were typed for HLA-A, B, C, DR, and DQ antigens and were compared with age and sex matched controls with cystic fibrosis. The diagnosis of cystic fibrosis arthritis and hypertrophic osteoarthropathy was confirmed by radiography and bone scanning. The prevalence of HLA-A, B, C, D, antigens in the cystic fibrosis group (44 patients) did not differ from that in the control group. A comparison between patients with cystic fibrosis arthritis or hypertrophic osteoarthropathy and their respective controls did not show any significant differences in HLA prevalence. It is concluded that HLA antigens may not be a factor in the susceptibility of patients with cystic fibrosis to cystic fibrosis arthritis or hypertrophic osteoarthropathy.

Exclusion mapping

The basis for using information against linkage to some loci to support linkage to other loci is discussed and data on cystic fibrosis available up to late July 1985 used as an example.

Linkage between the loci for cystic fibrosis and paraoxonase

In a material of 22 Danish, 26 Canadian, 10 Australian, 5 English and 5 American families with at least 2 children affected with cystic fibrosis (CF) a combined positive LOD score of 3.46 was found for the relationship cystic fibrosis-paraoxonase (PON) at recombination fraction theta = 0.07 in males and theta = 0.13 in females. Assuming a three allele model for PON the LOD score was 4.50 at the same recombination fractions. This confirms our earlier finding of an indication of CF-PON synteny.

Exclusion of human chromosome 13q34 as the site of the cystic fibrosis mutation

We have studied a family in which both cystic fibrosis (CF) and an unbalanced translocation between chromosomes 6 and 13 are found. As CF occurs in the child who is effectively monosomic for the translocated part of the long arm of chromosome 13, it was suggested that the locus of the gene mutation causing CF is on chromosome 13q34. The gene for human coagulation factor X is located at 13q34, and we have found a restriction fragment length polymorphism (RFLP) that is revealed by a cloned cDNA coding for this protein. Linkage analysis in eight CF families shows no evidence of cosegregation between CF and the gene for factor X, strongly suggesting that the locus for the defect causing cystic fibrosis is not at 13q34.

The musculoskeletal manifestations of cystic fibrosis

Twenty-seven patients with CF and joint complaints were reviewed. Twelve patients had arthritis, 11 had HPO, and four had symptoms of mechanical neck and back pain. We have confirmed the association of CF with an episodic form of arthritis. For the first time, we have reported that a subgroup of these patients later develop persistent synovitis with progressive asymmetric, erosive disease. The etiology of CF arthritis is unclear, but may relate to chronic infection and immune complex mechanisms. CF arthritis can be contrasted with CF induced HPO, which is associated with worse lung disease, a male predominance, and an older mean age of onset of symptoms. Mechanical neck and back pain may relate to an associated scoliosis or kyphosis in CF.

The analysis of multiple polymorphic loci on a single human chromosome to exclude linkage to inherited disease: cystic fibrosis and chromosome 4

Classical linkage programs analyze the segregation of two markers in informative families. When several markers are available for one human chromosome, pairwise analysis can exclude linkage between each marker and an inherited disease. The identification of restriction fragment length polymorphisms has made many new informative markers, assigned to chromosomes, available. We have adapted the multipoint linkage program MLINK developed by Lathrop et al. in order to exclude linkage between cystic fibrosis and several markers known to be on human chromosome 4. The exclusion obtained is greater than that for a pairwise analysis.

Linkage relationships of paraoxonase (PON) with other markers: indication of PON-cystic fibrosis synteny

The linkage relationships of the serum arylesterase paraoxonase (PON) was examined in our Danish material of normal families and in Danish and English cystic fibrosis families. Highest lod scores were found between PON and cystic fibrosis. The combined lod score for this relationship was z = 2.69 at theta = 0.07 in males and theta = 0.00 in females. When scored in accordance with a tentative three allele model for PON, the score was z = 3.70 at the same theta values. Linkage studies for PON against 64 other polymorphic marker systems did not give any lod score above +1.3 and PON still remains chromosomally unassigned. By the present screening about 2/3 of the genome could tentatively be excluded as the region of PON and cystic fibrosis.

Linkage studies between polymorphic markers on chromosome 4 and cystic fibrosis

It has been suggested that a protein factor causing ciliary dyskinesis is a marker for the basic defect causing cystic fibrosis (CF), and that the structural gene for this protein may be (amongst others) on human chromosome 4. We have isolated two DNA sequences mapping to chromosome 4 which show restriction fragment length polymorphisms (RFLPs), and have followed their segregation in families in which cystic fibrosis occurs. Eleven families with a total of 30 children with CF and ten unaffected sibs were studied. We have also followed the inheritance of RFLPs revealed by two probes mapping to chromosome 4 and obtained from another laboratory, polymorphisms revealed by cloned coding sequences for albumin and fibrinogen, and the inheritance of the MNS blood group. Although the level of albumin is altered in children with CF, the gene does not segregate with CF, and therefore albumin can be excluded as the site of the basic defect. Tight linkage with CF was not found with any of the seven markers investigated, and therefore, assuming that the markers (excepting MNS and fibrinogen) are unlinked to one another, approximately half of the total genetic length of chromosome 4 may be excluded.