Potter Sequence - Genetics

Genetics

While genetic research has linked certain genetic mutations to be the cause of ARPKD, ADPKD and possibly MRD, to date no genetic mutation or chromosomal anomaly has been linked to be the cause of BRA. Chromosomal anomalies have been associated with BRA in certain cases (chromosomes 1, 2, 5 and 21), but these anomalies were not inherited and have not been observed in subsequent cases. Additionally, neither extreme substance abuse or environmental factors (high power line, mercury, etc.) have been reported to be linked to an increased incidence of BRA or other cause of Potter sequence. BRA and other causes of oligohydramnios sequence have been linked to a number of other problems, to include Down syndrome, Kallmann syndrome, branchio-oto-renal syndrome and others.

The high-risk obstetrician or genetic counselor may ask for a blood sample from the fetus or will perform an amniocentesis. These samples are used to perform several tests, one of which may be to check for the proper number of chromosomes, called a karyotype, of the fetus. Some birth defects are known to be associated with missing a chromosome, having an extra chromosome, such as in Down syndrome, as well as by having a part of one chromosome break off and relocate to a portion of another chromosome (called a translocation). However, on each of the 23 pairs of chromosomes are thousands of different genes. While chromosomes are easy to visualize under a microscope and count, the genes on them are not. Genes are very small pieces of DNA when compared to the chromosomes they reside on. A gene contains a code for a protein and if the gene is mutated (different from normal) the protein that is made from it may not function properly - if at all. Unfortunately, genetic abnormalities could still exist despite having normal chromosomes. The only way to determine genetically inherited mutations in the infant is to perform a genome scan of the mother, father, affected infant and any unaffected siblings of the affected fetus. These analyses will reveal what genetic mutations are present in the affected infant, and by comparing these results to the surviving siblings and parents, it can be determined which mutations were inherited or were not.