Chromosome 9p duplication syndrome. Rethoré syndrome. 9p+ syndrome. Trisomy 9p.
Incidence
Very rare syndrome. Sporadic. In some cases, the trisomy appears to result from a balanced chromosomal rearrangement in one of the parents; in others, it is thought to arise from spontaneous (de novo) errors very early in embryonic development that occur for unknown reasons (sporadically).
Clinical Characteristics
Chromosome 9, Trisomy 9p is a rare chromosomal syndrome in which a portion of the 9th chromosome appears three times (trisomy) rather than twice in cells of the body. The trisomy may involve a portion of the short arm (9p), the entire short arm, or the short arm and a portion of the long arm (9q) of chromosome 9. (Each chromosome contains a short arm known as "p" and a long arm designated as "q.") Evidence suggests that, in many cases, associated symptoms and findings may be relatively similar among affected infants despite differing lengths of the trisomic (duplicated) segment of 9p. However, in those with larger trisomies (e.g., extending to middle or end [distal] regions of 9q), additional features may also be present that appear to correlate with the extent of the duplication. Virtually all individuals with Trisomy 9p are affected by mental retardation and distinctive malformations of the skull and facial (craniofacial) region. In some instances, additional physical abnormalities may also be present, such as other skeletal defects, structural malformations of the heart that are present at birth (congenital heart defects), and/or other findings. In some cases, the trisomy appears to result from a balanced chromosomal rearrangement in one of the parents; in others, it is thought to arise from spontaneous (de novo) errors very early in embryonic development that occur for unknown reasons (sporadically). Duplication of the short arm of chromosome 9 presents with psychomotor retardation, hypertelorism, deep-set eyes, downslanting palpebral fissures, large nose, short upper lip, down-curved corners of the mouth, cup-shaped ears, kyphoscoliosis, small hands and feet, characteristic dermatoglyphic patterns, and cryptorchidism.
Precipitants
None
Provocation Tests
None
Diagnostic Procedures
Karyotype. Duplication of the short arm of chromosome 9.