Sarah, age 14 months, was born with microcephaly, small head (cranium) size and is severely retarded. Chromosome analysis indicates that she lacks a piece of one of her number 13 chromosomes. Her parents come in to have their chromosomes analyzed to see whether one of them may have been a carrier for a translocation that could result in children affected like Sarah or children with other chromosomal, anomalies.
I understand your concern but that specific genetic anomaly which you are quoting itself can be a risk factor for microcephaly, please. So it is appropriate that both the parents need to be tested for genetic analysis if either one of them is the carrier to predict the future pregnancy risk.
Hope I have answered your query. Let me know if I can assist you further.