Trisomy 18
By Levi Clancy for Student Reader on
updated
- Genetic disease
- Androgen Insensitivity
- Balanced Rearrangement
- Cancer genetics
- Chromosome Number Abnormalities
- Cystic Fibrosis
- Down Syndrome
- Duchenne Muscular Dystrophy
- Fragile X Syndrome
- Hemoglobinopathy
- Huntington Disease
- Hurler Syndrome
- Hyperphenylalaninemia
- Nondisjunction
- Penis-At-Twelve Syndrome
- Relative Risk
- Sickle Cell Disease
- Spinal Muscular Atrophy
- Tay-Sachs Disease
- Thalassemia
- Triplet Repeat Expansions
- Trisomy 13
- Trisomy 18
- Unbalanced Rearrangement
- Uniparental Disomy
- mRNA Splicing Aberrations
Trisomy 18 is one of only three thoroughly-studied viable non-mosaic autosomal disorders (the others being trisomies 18 and 21), all of which result in stunted growth, mental retardation and multiple congenital deformities. Trisomy 18 frequently arises via translocation of all or most of Chromosome 18. Trisomy 18's phenotype is mental retardation in all cases, with most cases also involving: severe heart malformation; a receded jaw (overbite); low-set malformed ears; rocker-like feet; and hypertonia, usually leading to unique clenched fists characteristic of trisomy 18.