A 10 year old male, although mentally retarded, is able to carry out activities of daily living, including feeding and dressing himself.On physical examination, he has branchycephaly and oblique palpebral fissures with prominent epicanthal folds. On the palm of each hand is seen a transverse crease. On auscultation of the chest, there is a grade III/IV systolic murmur. Which of the following diseases will be most likely have by the age of 20 -

From the symptoms, the patient is suffering from Down&;s syndrome. Down syndrome is the most common of the chromosomal disorders. About 95% of affected persons have trisomy 21. Children with trisomy 21 have a 10- to 20-fold increased risk of developing acute leukemia. Both acute lymphoblastic leukemias and acute myeloid leukemias occur. Viually all patients with trisomy 21 older than age 40 develop neuropathologic changes characteristic of Alzheimer disease Approximately 40% of the patients have congenital hea disease, most commonly defects of the endocardial cushion, including atrial septal defects, atrioventricular valve malformations, and ventricular septal defects (Robbins Basic Pathology, 9 th edition. page : 237)