Trisomy 8 and trisomy 9 are distinctly different clinical entities.
Schinzel
A
A
D000015:Abnormalities, Multiple / Q000235:genetics*; D025063:Chromosome Disorders; D002898:Chromosomes, Human, Pair 8; D006801:Humans; D007223:Infant; D008297:Male; D009030:Mosaicism; D014314:Trisomy