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Enzymatic (PK, CK) levels and genetic counseling in duchenne muscular dystrophy

Maria Raquel S. Carvalho^I; Francisco M. Salzano^II; Mayana Zatz^III; Fernando J. da Rocha^II

^IUnidade de Genética Médica, Hospital de Clínicas de Porto Alegre, Ramiro Barcelos, 2350, 90210 Porto Alegre, RS, Brasil. Send correspondence to M.R.S.C.
^IIDepartamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Caixa Postal 1953, 90001 Porto Alegre, RS, Brasil
^IIIDepartamento de Biologia Geral, Instituto de Biociências, Universidade de São Paulo, Caixa Postal 11461, 05499 Sao Paulo, SP, Brasil

ABSTRACT

Twenty-nine patients affected with different forms of muscular dystrophy were ascertained and clinically studied. Pyruvate kinase (PK) and creatine kinase (CK) levels were also determined for 21 of these patients, who had the Duchenne type of the disease. Sixty-eight of their female relatives and normal controls were similarly investigated. Among these patients, serum enzyme levels showed an increase of the order of 15x (PK) and 112x (CK); six of the eight obligate heterozygotes were detected using both enzymes and five of them were detected using one enzyme only. Correlation coefficients between PK and CK levels were generally high (r: 0.79-0.84) for patients and obligate carriers, and decreased in individuals whose probability of having the abnormal gene also decreased. The concomitant use of both enzymes combined with the maximum information available from each genealogy permitted us to determine high (above 80%) and low (below 20%) risks of heterozygosity for 90% of the patients' relatives who asked for genetic counseling.

Keywords: enzymatic; genetic; counseling; duchenne muscular dystrophy.

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