[Cytogenetic and clinical aspects of Prader-Willi syndrome].

Two male nonconsanguineous cases (aged 4 years) of Prader-Willi syndrome are clinically and cytologically studied. Both had obesity, marked hypogonadism, reduced head circumference, psychomotor impairment, hypotonia, tooth decay, small hands and feet, immature EEG. Case 1 showed a "de novo" translocation 7;15 and case 2 showed a normal karyotype. According to various authors, many cases of Prader-Willi syndrome show the presence of a translocation of chromosome 15 onto an autosome or X chromosome. This is the first observation of chromosome 7 involvement in this translocation.