I am reading a journal paper about a patient who has intellectual disability. The patient was found to have a balanced chromosomal translocation t(11;16)(q24.2;q24).
This chromosomal translocation disrupted two genes: CDH15 and KIRREL3. By using a genomic probe, the authors fine mapped the 16q24 translocation breakpoint to the second intron of CDH15. The chromosome 11 breakpoint junction sequence mapped to intron 1 of KIRREL3. Only one chromosomal copy of CDH15 and KIRREL3 were disrupted.
However, there is something about this paper that I don't fully understand. The authors state in the following:
We began by sequencing both copies of the CDH15 and KIRREL3 genes in the patient with the translocation. No alterations were identified, indicating that the t(11;16) translocation does not unmask a recessive mutation in either gene.
In the above, it seems that the authors are trying to identify whether there are any recessive mutations in the CDH15 and KIRREL3 genes. I have read online that a recessive mutation is one in which both alleles must be mutant in order for the mutant phenotype of be observed.
However, since the chromosomal translocation disrupted one of the alleles for both CDH15 and KIRREL3, wouldn't you need both alleles of the CDH15/KIRREL3 genes to be intact in order to successfully identify a recessive mutation?
Any insights are appreciated.