Inability of a man to synthesise tyrosine results in

Phenylketonuria (PKU) is a genetic disorder that is characterised by an inability to metabolise the amino acid phenylalanine. PKU is caused by a deficiency of the enzyme phenylalanine hydroxylase, which is responsible for converting phenylalanine to another amino acid called tyrosine. If left untreated, PKU can cause intellectual disability and other serious health problems. 

Alzheimer's disease is the most common cause of dementia in older adults and is characterised by the abnormal accumulation of amyloid beta protein in the brain. 

Thalassemia is an inherited blood disorder that affects the production of haemoglobin. 

Cystic fibrosis is a genetic disorder characterised by the production of thick, sticky mucus that can block the airways and other serious health problems.