The pituitary gland is an endocrine gland the size of a pea that is made up of two separate, structurally and functionally separate parts known as the anterior and posterior lobe. The anterior lobe of the pituitary gland secretes six hormones essential for growth, reproduction, and other essential physiological functions. Abnormal development of the pituitary gland, or hypopituitarism, can cause a mild or complete deficiency of one or more pituitary hormones, which appear as highly variable symptoms. Tumors mainly cause hypopituitarism in humans, but a congenital factor can also be associated with this disorder.
The POU1F1 gene regulates the development of the anterior lobe of the pituitary gland, and the disturbance in its function leads to hormonal changes, which in affected dogs are manifested as dwarfism and abnormalities of the coat. A gene test developed based on the results supports the diagnosis and a breeding program to eliminate disease from the strain.
Roughly 30 genes have been associated with inherited hypopituitarism in humans, many of which are regulatory genes that affect pituitary development. In addition to humans, the pituitary gland malfunctions in mice and dogs. In German Shepherds, hypopituitarism was previously associated with the LHX3 gene, while in the case of Karelian Bear Dogs, the disease was described in Denmark already 45 years ago. Now, we have identified a related cause in the POU1F1 gene. This is only the second canine model of human pituitary disease, making it so important, says Professor Hannes Lohe.
Study samples were collected from asymptomatic and asymptomatic Finnish and Swedish Karelian Bear Dogs.
“We were able to obtain samples from a total of eight sick dogs from five different mothers. The size of the pups was up to 20 cm smaller than normal, and many of them also had a puppy-like coat or significant hair loss. Symptoms of the typical disease varied. It was also found. A handful of carriers of the POU1F1 variant in Lapponian Herders in an analysis of more than 8,000 dogs, says Kaisa Kyöstilä, PhD, first author of the article.
The study confirmed that the disease is inherited recessively, meaning that affected dogs inherit the genetic variant from both parents. Among Karelian Bear Dogs, only 8% of the breed carry this defect, and their carriers do not develop the disease. A gene test based on research results can be used to identify carriers, avoid groups of vectors in reproduction and eliminate this severe disease from the strain completely.
The most recent discovery of the POU1F1 gene is indeed the third disease gene described in Karelian Bear Dogs. The research group previously described gene discoveries associated with dwarfism (link in Finnish only) and phosphate deficiency.
The study is part of Professor Hans Lohe’s genetic research program at the Faculties of Veterinary Medicine and Medicine, University of Helsinki, and Folklore Research Center. This study was supported in part by the Dog Health Research Fund, the Jane and Athos Erko Foundation, the Academy of Finland and HiLIFE – Helsinki Institute of Life Sciences and Wisdom Health.