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Canine Mendelian disease record

Congenital Cornification Disorder (Discovered in the Chihuahua)

Congenital Cornification Disorder (Discovered in the Chihuahua). X-linked semi-dominant. Observed in 1 of 211 breeds tested in the Sniff Atlas, with measured at-risk genotype frequencies drawn from 12,296 dogs (Donner 2023). Because this is a dominant trait, a single copy places a dog at risk rather than making it a silent carrier; whether the phenotype appears still depends on penetrance, modifier genes, and environment.

Dominant trait. A single copy of this variant places a dog at risk; it does not make the dog a silent carrier. The breed frequencies below are therefore at-risk frequencies, and penetrance plus modifier genes determine whether the phenotype actually appears.

OMIA identifier
OMIA:002117-9615
X-linked semi-dominant
Source dataset
Sniff Atlas v1.0.1 / DOI
The human connection

A model of human CHILD syndrome

This is the canine counterpart of CHILD syndrome in people. That makes affected dogs a naturally-occurring model of the human disease, and it is part of why studying dogs moves medicine forward for everyone. It does not mean your dog has the human disease. It means the two share an underlying biology.

In people, the disease is described as: CHILD syndrome (Congenital Hemidysplasia with Ichthyosiform nevus and Limb Defects, CS) is an X-linked dominant genodermatosis characterized by unilateral inflammatory and scaling skin lesions with ipsilateral visceral and limb anomalies.

In humans it is also called: child nevus, CHILD syndrome, X-linked dominant, Ichthyosis, CHILD Syndrome, ichthyosis, child syndrome.

MONDO:0010621 OMIM 308050

Mapped from OMIA via the human disease's OMIM entry to the Mondo Disease Ontology (Monarch Initiative, CC-BY 4.0). Sniff renders this as a model-of link; the canine disease remains the subject of this page.

About this disease

From OMIA's curated record

Documented in OMIA (Online Mendelian Inheritance in Animals). This describes the disease as recorded in the published literature, not a prediction for any individual dog. As of 2026-06-03.

Summary

De Lucia et al. (2019): "Veterinary clinicians should be aware of cutaneous mosaicism and consider X-linked genodermatoses when seeing female cases with segmental cutaneous diseases like the one following the Blaschko’s lines."

Clinical features

Bauer et al. (2017):"No abnormalities were found on the affected daughter during general physical examination except a stunted growth. Linear hyperplastic and partially alopecic lesions, covered with thick brown scales and clusters of dilated follicular ostia were the most prominent dermatological features (Figure 1). The lesions were distributed along Blaschko’s lines in a bilateral rather symmetrical fashion and were more evident on the limbs, the head, the neck and the dorsal trunk. The abdominal and inguinal skin appeared normal. Frond like hyperkeratotic lesions at the margin of all the pawpads with occasional horn-like projections were considered the most probable cause of the visible lameness. Cytological examination of the linear hyperplastic lesions, revealed the presence of variable numbers of coccoid bacteria and a large number of Malassezia yeasts which were suspected to substantially contribute to the pruritus and the offensive odor. Results of the blood tests and urinalysis were unremarkable." De Lucia et al. (2019): "Alopecic scaly plaques following the Blaschko’s lines on the limbs, the head, the dorsal neck and the trunk, and severe foot pads hyperkeratosis were the most relevant lesions"

Molecular genetics

Bauer et al. (2017):"a deletion spanning 14,399 bp including the last three exons of the NSDHL gene . . . . The formal variant designation is chrX:120,749,179_120,763,577del14,399".
Leuthard et al. (2019) detected a heterozygous missense variant in NSDHL in a female affected Chihuahua, c.700G>A or p.Gly234Arg.
Christen et al. (2020): "A heterozygous frameshift variant, c.718_722delGAACA, was identified in . . . a female Chihuahua cross with a clinical and histological phenotype consistent with progressive epidermal nevi"
Kiener et al. (2024) "describe an Appenzeller Mountain Dog with clinical signs suggestive of an NSDHL defect. ... Genetic investigation revealed a large heterozygous de novo deletion spanning the entire NSDHL gene."

Pathology

Bauer et al. (2017):"The histopathological findings were identical in all biopsies . . . . Multifocally, the epidermis and the wall of the hair follicular infundibuli were moderately to severely hyperplastic with abrupt transition to normal skin. Within the hyperplastic area the infundibular epithelium was covered by thick layers of densely packed parakeratotickeratin which was distending the infundibuli. The parakeratotic keratin was often protruding above the epidermal surface. The size of the keratohyalin granules within the granular cell layers of the epidermis and the infundibular wall was within the normal range. Within the parakeratotic keratin, multifocally variable numbers of coccoid bacteria were present and occasionally the lumen of infundibuli contained degenerate neutrophils. Sebaceous glands appeared normal. The interfollicular epidermis was covered by moderate to large amounts of laminar to compact mostly orthokeratotic, but also some parakeratotic keratin. Within the keratin layers of the epidermis multifocally degenerate neutrophils, nuclear debris and small numbers of coccoid bacteria were present. Multifocally exocytosis of neutrophils was seen. Within the superficial dermis there was a mild pigmentary incontinence and a moderate perivascular infiltrate composed of neutrophils, mast cells and fewer lymphocytes."

Inheritance

De Lucia et al. (2019): "In heterozygous females, with an X-linked dominant or semidominant genodermatosis, . . . random inactivation of the X chromosome is responsible for the development of normal and abnormal skin segments distributed in a mosaic pattern. In fact, normal skin derives from progenitor cells in which the X-chromosome carrying the pathogenic variant has been inactivated, whereas stripes or patches of abnormal skin result from progenitor cells after the inactivation of the wild-type (normal) X-chromosome. X-linked cutaneous mosaicism can be heritable and is normally observed in heterozygous females." The trait is embryonic lethal in hemizygous mutant males (Bauer et al. 2017).

Human analog

OMIA links this condition to its human counterpart in OMIM (Mendelian Inheritance in Man), the place to read across to the deeper human literature for the same biology.

Disease · OMIM 308050 Gene · OMIM 300275

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:002117-9615, doi:10.25910/2AMR-PV70 (CC-BY 4.0).

The evidence

Published references

The peer-reviewed papers behind this disease, curated by OMIA. Starred entries are OMIA-designated landmark papers. Showing 6 of 11.

  1. Development of cost-effective PCR-RFLP methods for screening Mendelian disorders in Chihuahua dogs. · F.U. Vet. J. Health Sci. · 2026
  4. Genetics of inherited skin disorders in dogs. · Vet J · 2022 · PMID 34861369
  5. Ichthyosis and hereditary cornification disorders in dogs. · Vet Dermatol · 2021 · PMID 34796560

References curated by OMIA (Nicholas, Tammen & the Sydney Informatics Hub), doi:10.25910/2AMR-PV70 (CC-BY 4.0). Full list at the OMIA entry.

Predict a litter

Set each parent's status for Congenital Cornification Disorder (Discovered in the Chihuahua) and see the odds for their puppies. Single dominant variant, exact Mendelian math.

Parent A
Parent B
NDAffected
NDAffected
NNUnaffected
NNUnaffected
Unaffected50%
Affected50%

These are the genetic odds for one known variant, not a promise: a real litter varies around them, and penetrance or other genes can change whether the condition ever appears. Use it to avoid pairing two carriers and to keep a line healthy, not to engineer a dog. Inheritance mode per OMIA.
Your breed

See what Congenital Cornification Disorder (Discovered in the Chihuahua) looks like in your dog's breed.
At-risk frequency by breed

Observed only in small-sample breeds

Maximum at-risk frequency per breed across variants in the Donner 2023 cohort, with . The list below is split into well-sampled breeds (n ≥ 50 tested) and small-sample breeds (n < 50, where the Wilson CI typically spans more than 20 percentage points and frequencies should not be compared directly to the well-sampled entries). Frequencies are population-level, not per-litter or per-line.

▸ Also observed in 1 small-sample breed (n < 50)

Frequencies in this section are statistical estimates with wide Wilson 95% confidence intervals (typically >20 percentage points). Treat these as "at-risk dogs observed but the true population frequency is not yet measurable" rather than as comparable to the well-sampled entries above.

Breed Estimate n tested
Azawakh 11.5% 13

210 additional breeds in the Donner 2023 cohort were tested but showed no at-risk genotypes.

Scope of this record

Scope

This record carries the breed-level carrier frequencies from the Donner 2023 cohort. Penetrance data (the fraction of at-risk dogs that develop the phenotype) is not yet quantified for this disease in the Sniff Atlas v1.0.1. The OMIA entry is the authoritative reference for the clinical phenotype, inheritance pattern, and gene assignment.

Predicted disease relevance at the per-dog level is UNPROVEN. The at-risk frequency is measured; phenotype outcome depends on penetrance, environment, and modifier loci. Consult a veterinarian for clinical interpretation.

How to cite this record

Citations

If you use this record in published work, cite the Sniff Atlas (the published dataset that carries the breed-level carrier frequencies) and the upstream sources:

  • Sniff Atlas v1.0.1 for the per-breed carrier frequencies:

    Gehring, M. (2026). Sniff Atlas v1.0.1. Zenodo. https://doi.org/10.5281/zenodo.20566358. CC-BY 4.0.

  • OMIA for the disease definition, inheritance, and gene assignment:

    Nicholas, F. W., & Tammen, I. (2024). OMIA. Sydney Informatics Hub, The University of Sydney. https://doi.org/10.25910/2AMR-PV70. Entry: OMIA:002117-9615.

  • Donner et al. 2023 for the breed × variant carrier-frequency cohort:

    Donner, J., Freyer, J., Davison, S., Anderson, H., Blades, M., Honkanen, L., et al. (2023). Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs. PLOS Genetics, 19(2), e1010651. https://doi.org/10.1371/journal.pgen.1010651.

Full citation formats (BibTeX, RIS, CITATION.cff) at sniff.world/cite.

Related

Related

Last updated
Sources: Sniff Atlas v1.0.1 · OMIA OMIA:002117-9615 · Donner et al. 2023