The relative significance of different aggregation species may depend on the protein involved and the organ system affected. Diagnosis
Diagnosis of amyloidosis generally requires tissue biopsy. The biopsy is assessed for evidence of characteristic amyloid deposits. The tissue is treated with various stains. The most useful stain in the diagnosis of amyloid is Congo red, which, combined with polarized light, makes the amyloid proteins appear apple-green on microscopy. Also, thioflavin T stain may be used. A number of imaging techniques such as a DPD scan or SAP scan are also in use.A sample of tissue can be biopsied or obtained directly from the affected internal organ, but the first-line site of biopsy is subcutaneous abdominal fat, known as a "fat pad biopsy", due to its ease of acquisition. An abdominal fat biopsy is not completely sensitive and may result in false negatives, which means a negative result does not exclude the diagnosis of amyloidosis. However, direct biopsy of the affected organ may still be unnecessary as other less invasive methods of biopsy can also be used, including rectal mucosa, salivary gland, lip, or bone marrow biopsy which can achieve a diagnosis in up to 85% of people.In the amyloid deposition of the joints, there will be a decreased signal in both T1 and T2 weighted MRI images.
Up to 40% of women with a urogenital tract anomaly also have an associated renal tract anomaly.Adults with unilateral renal agenesis have considerably higher chances of hypertension (high blood pressure). People with this condition are advised to approach contact sports with caution. A possible complication later in life of unilateral renal agenesis is Focal Segmental Glomerular Sclerosis (FSGS) which will cause nephrotic syndrome, potentially resulting from glomerular overload. Genetics
In 2008 researchers found autosomal dominant mutations in the RET and GDNF genes to be linked to renal agenesis in unrelated stillborn fetuses through PCR and direct sequence analysis. In the study, DNA from 33 stillborn fetuses were sequenced for mutations in RET, GDNF and GFRA1. Nineteen of the fetuses had BRA, ten had URA and 4 had congenital renal dysplasia. Seven of the 19 BRA fetuses were found to have a mutation in the RET gene (37%), while two of the ten URA fetuses did (20%). One of the URA fetuses had two RET mutations and one GDNF mutation. There were no GFRA1 mutations found.However, the results of Skinner et al. study were questioned by a more recent study with a larger number of cases. In this study 105 fetuses were analyzed. Sixty-five fetuses had BRA while 24 had URA with an abnormal contralateral kidney. Mutations in the RET gene were only found in seven of the fetuses (6.6%).In 2014 researchers found autosomal recessive mutations in ITGA8 in three members of two unrelated families utilizing Exome Sequencing.