Nothing is more devastating than waiting almost one year for a cria to arrive, and when it is here, it is born with a birth defect. Genetic studies are being done on alpacas at this time, but at this point the etiologies of many birth defects are unknown. I haven't had a cria born with CA (or any other birth defects, for that matter), but I can understand the knee-jerk reaction to remove all related individuals from the gene pool. But I believe that determination needs to be made with scientifically based data, rather than tradition.
Some of these articles may not be alpaca related, but I have included them to give an overview of the etiology in other species.
Choanal Atresia - this is a web site devoted to CHARGE syndrome in humans. The "A" stands for atresia of the choanae. I think the most telling part of this page is about 3/4 of the way down - " In the vast majority, the mutation was new in the child - not detected in the parents." It is a small sampling of children - only ten in number, but none the less speaks volumes in the spontaneous nature of the defect in the cases invovled. Also mentions the fact that parents with an affected child are not counseled against having further children.
Choanal Atresia part II - on page 5, below the pictures in Fig. 5, is this paragraph:
The present study reveals that aldh1a3-null mutants display
severe malformations of the nasal cavities, including CA, which
results in a lethal respiratory distress syndrome at birth. On the
other hand, the associated ocular defects are much milder and
may remain functionally silent. Importantly, the occurrence of
CA can be prevented by maternal administration of nonteratogenic
doses of RA, thus providing the demonstration that a
lethal genetic defect can be prevented by a simple treatment with
a vitamin derivative. Isolated CA is a rare, heritable, developmental
defect in humans (39). Our present data suggest that it
could be due to mutation(s) at the aldh1a3 locus. Such mutation(
s) could also be at the origin of the isolated cases of CA that
have devastating consequences on breeding programs of llamas
(48). Whether maternal RA administration could prevent CA in
this species remains to be investigated.
To me, the most important sentences are the occurrence of choanal atresia can be prevented by maternal administration of non–teratogenic doses of RA and the last sentence about llamas. Interesting stuff, and makes me seriously question breeders who advocate removal of all related individuals to the cria. Only time will tell who is right.