The breakpoints of some deletions are delineated within the DXS164 locus, and it is evident that the deletions at the DMD locus are frequent and extremely large.
The similarities between this patient and previously reported females with Duchenne muscular dystrophy are discussed with reference to de novo translocations with a breakpoint at Xp21 and the risk of DMD in such females.
Nine unrelated pedigrees in which Duchenne muscular dystrophy (DMD) was not present in more than one sibship were studied, using 6 DNA polymorphisms closely linked to the DMD gene.
A sequence derived from the X-chromosomal portion of the clone detects a restriction fragment length polymorphism (RFLP) which is closely linked to the DMD gene and uncovers chromosomal deletions in some male DMD patients.
A girl with full expression of DMD due to a 46 XY karyotype is reported, and other clinical conditions in which expression of the DMD gene occurs in females are reviewed.
Muscle cells were obtained from five doubly heterozygous carriers of two X-linked loci, DMD and glucose-6-phosphate dehydrogenase (G6PD), and compared with those from five sex- and age-matched controls heterozygous for G6PD only.
Although in the eight published cases of girls with DMD and a t(X;aut) different autosomes were involved in the translocation, the breakpoint was always at Xp21.
The biochemical activity of AMP deaminase did not decrease in muscle with mild pathologic change in patients with DMD and tended to decrease according to the progress of the disease.
The biochemical activity of AMP deaminase did not decrease in muscle with mild pathologic change in patients with DMD and tended to decrease according to the progress of the disease.
By cloning the endpoints of a DMD-associated deletion, we have "jumped" 1100 kb from pERT87-1 (DSX164) to a new locus designated J66 (DXS268), mapping distally within the Duchenne muscular dystrophy (DMD) gene.
Since the donor of one of these biopsies has a large deletion of the 5'-region of the DMD gene, our results argue against the recent proposal that nebulin is the gene mutated in DMD.
DNA prepared from these hybrids was probed with sequences physically close to the locus; these include a junction fragment from the site of the X:21 translocation (pXJ1) and subclones from the pERT 87 (DXS164) region which are absent in a minority of male DMD patients.
The segregation of DMD and the DXS164 deletion in this family illustrates the importance of extended pedigree analysis when DXS164 deletions are used to identify female carriers of the DMD gene.