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Children who have the disease may have some of a number of symptoms, including heart problems, speech and language problems, specific facial characteristics and mild to severe mental retardation. Many of the children are high functioning in spite of the challenges posed by the structural abnormality of their chromosomes. Environmental factors cause 7 to 10 percent of congenital anomalies and are throught to be the main cause of structural abnormalities.
Although the specific location of the chromosome deletion which 'qualifies' as Jacobsen's varies among the research articles which have been published, a parent group has been formed to provide support and organizational efforts for parents of all children with 11th chromosome abnormalities, including deletions (monosomy), duplications (trisomy) and translocations .
"Deletion" occurs when a chromosome breaks and a portion of the chromosome is lost. This is also called "monosomy". The incidence of 11q deletions is thought to be less than 1 in 100,000; however, partial trisomy ("duplication") of 11q seems to be even more rare.
"Duplication" of a portion of a chromosome
may attach to a chromosome or remain as a separate fragment. This is also
called "trisomy".
"Translocation" is the consequence of chromosomal breakage but the broken segment transfers itself to a broken segment of another chromosome. There are both balanced and unbalanced translocations. An example of a balanced translocation would be when the broken segment of the 11th chromosome transfers itself to the 22nd chromosome (for example) and the genetic material broken off the 22nd chromosome transfers itself to the 11th chromosome.
Information provided in a recent issue of the 11q Research and Resource
Newsletter,
Starla Pfeiffer, editor.
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