Читать книгу Essential Endocrinology and Diabetes - Richard I. G. Holt - Страница 39

Abnormalities in DNA (genetic)

 Base substitution – swapping different nucleotides

 Insertion or deletion – alters frame if exonic and not a multiple of three

Chromosomal abnormalities (genomic)

 Numerical – loss of an X chromosome as in Turner syndrome (45,XO)

 Structural:Inversion – region of a chromosome is turned upside downTranslocation – regions swapped between chromosomesDuplication – region of a chromosome is present twiceDeletion – region of a chromosome is excised and lost

Imprinting abnormalities (epigenetic)

 Methylation – altered methylation changing local gene expression, such as Beckwith–Wiedemann syndrome with neonatal hypoglycaemia or transient neonatal diabetes mellitus associated with over‐expression of the gene called PLAGL1

 Structural chromosomal abnormalities (above) can also cause imprinting errors