The stallion Apache is carrier of the WFFS-gene, which is shown by the recent test result of the hair sample of the KWPN-stallion. On May 24th we published the results of the research that had been conducted by Van Haeringen Laboratory on all active KWPN riding stallions. The KWPN was one of the first studbooks to decide to test the stallions, as we wish to inform our breeders optimally with regards to their stallion choice and also highly value a healthy population. The test results of Apache indicated that he was no carrier of the WFFS-gene. Early July, a number of Apache-descendants turned out to be carrier, also ones that came out of dams that had tested negatively themselves. A carrier always has one parent that is carrier, that is why the KWPN, in agreement with Ad Valk Dressage Horses BV, had the stallion Apache retested based on a newly taken hair sample.

For the original test, the KWPN requested the DNA-samples at the Van Haeringen Laboratory that had been used for the identity check of the offspring of the stallion, to be sure that the right sample would be tested. This DNA-sample can consist of hair roots, blood, semen or other tissue. For the vast majority of the stallions a hair sample is available, for Apache a blood sample was used. In examination of the blood sample of Apache has been made a mistake at the Van Haeringen Laboratory. Apache was classified as a ‘non-carrier’ while the test results of the recently taken second test (on the hair sample) shows that Apache is in fact carrier of the WFFS-gene.

The research into the WFFS-carriers was conducted based on a blood sample for a total of two stallions. Besides Apache this was one other KWPN-stallion and a number of non-KWPN horses. All these horses have been retested and no mistakes were found, making the results consistent with the ones published earlier. Therefore, there is no reason to doubt the on the KWPN-website published results of the active KWPN-stallions.

The Warmblood Fragile Foal Syndrome is a genetic disorder that bears no consequences for the suitability of the horse in the sport. As far as we now, the disorder is determined by one particular gene. Only if the stallion and mare are both carrier of the gene, a 25% chance arises that the foal suffers from WFFS, although there is an equally sizeable chance that the foal is completely free of WFFS and there is a 50% chance that the foal is also a carrier. If only the mare or stallion is a carrier, the foal can never suffer from WFFS, but there is a 50% chance that the foal is carrier of the WFFS-gene. A foal that suffers from WFFS may abort, be born prematurely and/or born with abnormalities. The most important abnormalities of the newborn foal are: skin abnormalities (such as a too elastic skin that tears easily, wounds that appear ‘out of nowhere’) and hyper extension of the joints. In general, foals are non-viable. It is advisable to test the broodmares, so you know if your mare is a carrier.

The Van Haeringen Laboratory deeply regrets the mistake. Below you find their response.

Response Van Haeringen Laboratory:

Based on the results of offspring, doubts were raised about the WFFS-result that was given by VHL for the stallion Apache. At the request of KWPN a retest was initiated, based on a newly supplied hair sample. The retest of the hair sample brought a different result forward than the one priorly given out by VHL. Where in first instance a blood sample of Apache was tested as ‘free’ for the WFFS-test, the hair sample was tested as ‘carrier’. We deeply regret this and therefore offer the breeders that expect a foal by Apache next year from a cover in the period of May 24th until today, July 31th 2018, a free WFFS-test for their foal.

From internal analysis it appears that at the extraction of the blood sample in which the initial result was issued, a human error occurred at the set-up of the DNA extraction. Directly following the establishement of the mistake, all the samples in the test batch have been retested. All other results were in accordance with the earlier issued results. Thus, it can be concluded that the mistake was limited to the result of Apache only. In addition, the other test batches have been checked for divergences independently from each other. During this check it was determined that the positive and negative reaction checks showed no discrepancies. Thus, it can be concluded that it is technically unlikely that other test mistakes have been made.

The procedures of the VHL provide that all the samples that will be tested, will be prepared by a trained lab technician, who is checked by a second, independent lab technician. Unfortunately, the VHL had to conclude that in spite of these strict procedures a mistake has been made at the set-up of the sample of Apache. Based on the deviating test result, additional measures have been taken to prevent sample mix-ups in the future. VHL aspires to provide her clients service of the highest possible quality. The organization ensures this by amongst others a management system that is certified by the ISO:9001-norm. In addition, the organization performs a portion of her tests under ISO:17025-accredditation. For that reason, we consider this casus as an incident.

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