Pelger-Huet Anomaly

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Pelger-Huët anomaly (PHA) is a rare, inherited blood condition in which the nuclei of several types of white blood cells (neutrophils and eosinophils) have unusual shape (bilobed or dumbbell-shaped) and structure (coarse and lumpy). It may also be called Pelger’s nuclear anomaly, or Pelger-Huët nuclear anomaly.

The disorder appears to be an autosomal dominant genetic trait (not related to sex of animal, and one copy of gene leads to disorder) that has been reported to occur in foxhounds, Samoyeds and other dogs, e.g. Basenji. It is also a known problem in Australian Shepherd dogs, although in this breed the penetrance of the trait appears incomplete (dog may have defective gene without exhibiting the disorder). It been reported in humans, rabbits, mice and domestic short-haired cats.

[By itself, PHA is no problem. It does not make the affected animal any more prone to infection. In other species it can be associated with additional problems. When homozygous in humans (two copies of defective gene) it is associated with skeletal abnormalities. In one family of Samoyeds, white cell changes similar to PHA were reported along with dwarfism and ocular problems. ]

Signs and Symptoms

When only one defective copy of the gene is inherited (heterozygous), PHA can exist by itself with no detrimental effect to the dog. However, if a defective gene is inherited from each parent (homozygous), the disorder in dogs is typically lethal in utero or shortly after birth, leading to:

  • Neonatal deaths
  • Lower litter sizes surviving to weaning than in normal dogs


In humans, mutations in the Lamin B Receptor (LBR) gene, which codes for a protein in the nuclear membrane, have been identified as being responsible for PHA. The responsible gene has not yet been identified in dogs.

Risk Factors

Related dogs with the condition

Diagnostic Tests

The condition is diagnosed by observation of white cells in a blood smear. Bilobed or dumbbell-shaped neutrophils with more condensed chromatin (nuclear material) are seen. The total white count is normal, but the differential count (distribution of types of white cells) is atypical.

As the condition is associated with some fairly extreme skeletal disorders in humans, and may have been seen with skeletal disorders in Samoyeds, it is wise to test for other symptoms that could be associated with PHA. For instance, if it is found in association with retinal folds, a degree of dwarfism could be suspected.

PHA must be distinguished from Pseudo PHA, which is an acquired condition with similar white cell changes. Pseudo PHA in humans has been associated with:

  • Blood disorders such as anemia, leukemia and myelodysplastic syndromes
  • Drug therapy with colchicines or ibuprofen
  • Infections such as mononucleosis and malaria

Treatment Guidelines

Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.

There is no treatment for this condition. Associated conditions should be treated according to their presentations.


As this condition has been associated with extreme skeletal disorders, it would be prudent to seek follow up screenings of parents and siblings, even if the diagnosed animal shows no other clinical signs. Siblings and parents should be screened with veterinarian consultations on the advisability of using the stock in future breedings.


  1. Aroch I, Ofri R, Aizenberg I. Haematological, ocular and skeletal abnormalities in a samoyed family. J Small Anim Pract. 1996 Jul;37(7):333-9.
  2. – picture of anomaly in a stained blood smear 3
  3. – photographs of stained blood smears (scroll down the page for Pseudo Pelger Hüet Anomaly 3 bones
  4. – Aussie Genetics Fact Sheet: Pelger-Huet Anomaly (PHA) by C.A. Sharp from the Australian Shepherd Health & Genetics Institute 2
  5. Vikramjit S Kanwar, Andrew L Sherman. Pelger-Huet Anomaly. eMedicine from webMD, September 2007 – Excellent up-to-date paper on PHA in human beings 3 bones

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Katrin Hoffmann, Karl Sperling, Ada L. Olins and Donald E. Olins. The granulocyte nucleus and lamin B receptor: avoiding the ovoid. Chromosoma Volume 116, Number 3 / June, 2007, pp227-235. –Excellent review of PHA 3 bones

Dusse LM, Morais E Silva RM, Freitas VM, Medeiros de Paula GM, Vieira LM, Carvalho MG. Pseudo-Pelger-Huët in kidney-transplanted patients. Acta Haematol. 2006;116(4):272-4. – Excellent paper on pseudo PHA (changes in blood cells that are similar to changes seen in inherited PHA) in Kidney transplant patients. Good frontispiece descriptions of the disease 2 bones

J C Oosterwijk1, S Mansour, G van Noort, H R Waterham, C M Hall and R C M Hennekam. Congenital abnormalities reported in Pelger-Huët homozygosity as compared to Greenberg/HEM dysplasia: highly variable expression of allelic phenotypes. Journal of Medical Genetics 2003;40:937-941. – Includes some of the history of research behind this disease. 3 bones

Tomonaga M. Nuclear abnormalities in Pelger-Huet anomaly; progress in blood cell morphology. [Article in Japanese] Rinsho Byori. 2005 Jan;53(1):54-60.

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