Deletion syndromes most often occur as a result of the loss of short arms of chromosomes.
Syndrome "cat's scream" is associated with the deletion of the short arm of chromosome 5 (syndrome 5p-). A typical symptom of the disease is the characteristic crying of a newborn, resembling the meowing of a cat (due to an anomaly in the development of the larynx and vocal cords). This symptom appears immediately after birth, persists for several weeks, and then disappears. In most cases, the syndrome also manifests itself in multiple malformations and mental retardation.
The 4p-deletion syndrome is very rare. Clinically it resembles the "cat's scream" syndrome, but there is no characteristic crying. Characteristic microcephaly, cleft palate, deep mental retardation.
Syndromes of microdeletions of neighboring genes. Microdeletions of neighboring genes on the chromosome cause a number of very rare syndromes (Prader-Willi, Miller-Dicker, Di-Georgie, etc.). Diagnosis of these syndromes became possible due to the improvement of the method of preparation of chromosome preparations. In the event that the microdeletion can not be detected by karyotyping, DNA probes specific to the region that has undergone deletion are used.
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