fra(1) (p11), fra(1) (q22) and r(1) (p11q22) in a retarded girl.
A mentally retarded girl with a 46,XX/47, XX+r(1) (p11q22q22p11)/47, XX+r(1) (p11q22) fra(1) (p31) fra(1) (p11) fra(1) (q22) karyotype who inherited the fragile sites from the normal mother was studied. The conicidence of fra(1) (p11) and fra(1) (q22) with the ring chromosome breakpoints strongly suggests a cause-effect relationship. This finding agrees with other reported associations between fragile sites and structural chromosome abnormalities and constitutes the fourth reported of a de novo structurally abnormal chromosome as a consequence of presumed in vivo fragile sites instability. Although risk figures for chromosome anomalies and cancer associated with fragile sites are lacking, carriers of fra (1) (p11) may have a higher risk for abnormalities of chromosome 1 in somatic and gonadal cells than the general population.
Ramírez-Dueñas
M L
ML
División de Genética, Instituto Mexicano del Seguro Social Guadalajara, Jalisco.
González
G J
GJ
D002675:Child, Preschool; D043283:Chromosome Fragile Sites; D002873:Chromosome Fragility; D002878:Chromosomes, Human, Pair 1; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D007621:Karyotyping; D012303:Ring Chromosomes