The COL4A3 and COL4A4 genes are affected equally often in both AD Alport syndrome and in AR Alport syndrome.
Genetic testing is the gold standard for diagnosis of AD and AR Alport syndrome. However even in people with strongly suspected AD Alport syndrome, no mutation may be identified in COL4A3 or COL4A4. This is because of limitations of Whole Exome Sequencing in detecting some of the disease-causing mutations.
With AD Alport syndrome the types of mutations indicates how severe the disease will be.
With AD Alport syndrome, the disease is inherited by half of the children of an affected person but not everyone who is affected necessarily develops blood and protein in the urine.
With AR Alport syndrome, the affected person has a one in four chance of having another affected family member. Their parents and their children will usually have only one copy of the COL4A3 or COL4A4 variant and will be diagnosed with AD Alport syndrome.
COL4A4