A chromosome disorder associated with TRISOMY of all or part of CHROMOSOME 18. Clinical manifestations include INTRAUTERINE GROWTH RETARDATION; CLEFT PALATE; CONGENITAL HEART DEFECTS; MICROCEPHALY; MICROGNATHIA and clenched fists with overlapping fingers. Most affected fetuses do not survive to birth. Those who survive through their first year often have severe INTELLECTUAL DISABILITY. [MeSH]
