This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
A 12 year old female patient complains of multiple missing teeth. The karyogram of  the patient is shown below. Intra-oral ﬁndings include missing 12, 17, 33 and 43.
Open bite, macroglossia and generalised periodontitis is also present. Which of the  following is commonly seen in this condition? 
Select and explain. 
A. Mouth breathing, B. Prognathic maxilla, C. Macrodontia, D. High level of caries
A: Mouth breathing
Answer: A: Mouth breathing 
Explanation: Patient is suffering from Down's syndrome (trisomy of chromosome No. 21).
Skeletal ﬁndings are an underdeveloped mid-face, creating a prognathic occlusal relationship. 
Oral ﬁndings include mouth breathing, open bite, appearance of macroglossia, ﬁssured lips and tongue, angular cheilitis, delayed eruption times, missing and malformed teeth, oligodontia, small roots, microdontia, crowding, and a low level of caries. 
Children with Down syndrome experience a high incidence of rapid, destructive periodontal disease, which may be related to local factors such as tooth morphology, bruxism, malocclusion, and poor oral hygiene.