Role of Adenotonsillectomy and Tonsillectomy in Children with Down Syndrome Who Develop Obstructive Sleep Apnea by Obesity as a Risk Factor

Table 1

Different origins of Down syndrome (trisomy 21).

Form of DS	Standard trisomy 21 (nondisjunction)	Robertsonian trisomy 21	Mosaic trisomy 21	Partial trisomy (21q22.3)
Frequency	95%	4%	3-5%	1%
Mechanism	Maternal meiosis 85-90%; (i) Meiosis I (75%); (ii) Meiosis II (25%)	Familial 25%	Mitotic	—
Mechanism	Parental meiosis 3-5%; (i) Meiosis I (25%); (ii) Meiosis II (75%)	De novo 75%	—	—
Chromosomal analysis	47 XX+21; 47 XY+21	46 XX/XY Robertsonian translocation between D and G chromosomes; (q10; q10)+21; 46XX/XY+21, i (21) (q10)	47 XX+21; 47XY+21; 46 XX; 46 XY	46 XX/XY, duplication (21) (q22.3)