Question

patients with down syndrome have three copies of chromosome 21, resulting in characteristics like a small head with a flat face and small ears, a short neck, a bulging tongue, upward slant eyes, and impaired development of the nervous system. why does a patient with down syndrome have these characteristics? due to reduced expression of genes resulting from missing genetic information due to the overproduction of proteins resulting from extra genetic information due to the abnormal multiplication of cells caused by environmental factors due to mutations in the cells of the patient caused by environmental factors

Explanation:

Down - syndrome patients have an extra copy of chromosome 21. This extra genetic material leads to overproduction of proteins encoded by genes on chromosome 21, causing the characteristic features.

Answer:

due to the overproduction of proteins resulting from extra genetic information