[Neonatal screening for duchenne myopathy by serum elevation of creatine phosphokinase activity. 5 years experience]

The systematic seek of an increased activity of the SCK among all newborns has permitted the detection of the Duchenne-type muscular dystrophy in the "Rhone-alpes" area. By the survey of 40,000 births during 5 years and the detection of 16 Duchenne-type muscular dystrophies the authors estimate the incidence of DMD at 1/6500 living new born boys. The number of false positives (1,5 p. 1000) is little and, up to now, no false negative has been recorded. A few boys and girls keep and increased activity of the SCK, and 3 boys hae a Becker-type muscular dystrophy.

[Early clinical and histopathological manifestations in 14 boys showing elevated serum creatine-phosphokinase levels in their first year]

The detection of Duchenne muscular dystrophy in the neonate by a determination of the serous activity of CPK allowed the authors to study the muscular, clinical and histopathological features among 14 boys born from 1976 to 1979, showing a raise in the enzymatic activity, confirmed during the first 6 months. 11 boys showed a Duchenne muscular dystrophy, and 3 likely a Becker muscular dystrophy. The authors point out the interest of early findings of hyaline degeneration of the fibers and indicate the variations, from one case to another, of the histopathological evolution in the pre-symptomatic stage. A well examined muscular biopsy is usually conclusive without using an electron microscope, from the age of one year, if serous activity of CPK reaches twenty times the normal rate. If not, waiting for the age of 2 would be advisable, since the initial lesions of the Becker D.M. are not yet clearly defined. When no systematic detection and no familial context, a dosage of the CPK serous activity should be made in the last during the third year, on every boy revealing an unexplained motor retardation. In that purpose, a definition and an application of a motor development score are proposed.

Duchenne muscular dystrophy: systematic neonatal screening and earlier detection of carriers

Systematic neonatal screening programme for DMD has been set up since June 1975. Constant and specific SCK increase in DMD newborn can be found on whole dried blood between the 5th and 8th day after birth. The amount of false positives is small : 1,6%. At the first control, DMD diagnosis is very probable and is made certain by EMG and muscle microscopic observations. For a period of 3 years and 6 months, we have achieved 138 579 screening tests, and 12 DMD were found, among 71 091 boys (1/5 929 male births). Genealogical data from 11 families out of the 12 lead to identify 93 women relatives as possible carriers; 23 of them are menstruating women who benefit by recognition and receive genetic information several years before the DMD clinical diagnosis in the first family's proband could have been done. Systematic neonatal screening programme for DMD seems to be a means to reduce the incidence of DMD to the theoretical mutation cases.

[Systematic neonatal screening for Duchenne muscular dystrophy]

More than 15% of cases of Duchenne muscular dystrophy (DMD) may be preventable by the neonatal diagnosis of another affected relative. Systematic neonatal screening seems a more efficient way of getting information for genetic counseling. The principle of the test described is the detection of a specific increase of the activity of Creatine-Kinase (CK) in the blood of newborn children with myopathy. Blood may be spotted on paper and posted to a central laboratory. Furthermore this program can be integrated into the systematic screening of phenylketonurie. The specificity and accuracy of the bioluminescent reaction used for the evaluation of CK suggest that this screening reaction is reliable. A systematic neonatal screening program for DMD such as ours in the Rhône-Alpes area (France) will lead to frequent recourse to prenatal diagnosis now possible through sex fetal determination and which would be possible through in utero blood sampling.