Chromosome 18q deletion syndrome. de Grouchy syndrome 2. 18q minus syndrome. Monosomy 18q
Incidence
It is a rare chromosomal disorder. Chromosome 18q- syndrome usually appears to result from spontaneous (de novo) errors very early during embryonic development that occur for unknown reasons (sporadically).
Clinical Characteristics
Chromosome 18q- syndrome is a rare chromosomal disorder in which there is deletion of part of the long arm (q) of chromosome 18. Associated symptoms and findings may vary greatly in range and severity from case to case. However, characteristic features include short stature; mental retardation; poor muscle tone (hypotonia); malformations of the hands and feet; and abnormalities of the skull and facial (craniofacial) region, such as a small head (microcephaly), a \\\"carp-shaped\\\" mouth, deeply set eyes, prominent ears, and/or unusually flat, underdeveloped midfacial regions (midfacial hypoplasia). Some affected individuals may also have visual abnormalities, hearing impairment, genital malformations, structural heart defects, and/or other physical abnormalities. Chromosome 18q- syndrome usually appears to result from spontaneous (de novo) errors very early during embryonic development that occur for unknown reasons (sporadically). Deletion of the long arm of chromosome 18 with a phenotype that may vary considerably, depending on the type of deletion and location of the breakpoint. The syndrome is marked mainly by mental retardation, midface hypoplasia, deeply set eyes, carp mouth, mild obesity, ataxia, hypotonia, malformed ears, and hyperactive and aggressive behavior. Neoplastic diseases may occur.
Precipitants
None
Provocation Tests
None
Diagnostic Procedures
Karyotype. Chromosome 18q- syndrome is a rare chromosomal disorder in which there is deletion of part of the long arm (q) of chromosome 18.