Alternative titles; symbols
SNOMEDCT: 39427000; ORPHA: 2309;
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
Gene/Locus |
Gene/Locus MIM number |
|---|---|---|---|---|---|---|
| 17q21.2 | Pachyonychia congenita 1 | 167200 | Autosomal dominant | 3 | KRT16 | 148067 |
A number sign (#) is used with this entry because pachyonychia congenita-1 (PC1) is caused by heterozygous mutation in the keratin-16 gene (KRT16; 148067) on chromosome 17q21.
Pachyonychia congenita (PC) is an autosomal dominant genodermatosis with the main clinical features of hypertrophic nail dystrophy, painful and highly debilitating plantar keratoderma, oral leukokeratosis, and a variety of epidermal cysts. Although the condition had previously been subdivided clinically into Jadassohn-Lewandowsky PC type 1 and Jackson-Lawler PC type 2, patients with PC were later found to have a mixed constellation of both types, leading to a classification of PC based on genotype (summary by Sybert, 2010; Eliason et al., 2012; McLean et al., 2011).
Historical Classification of Pachyonychia Congenita
Gorlin et al. (1976) suggested that 2 distinct syndromes are subsumed under the designation pachyonychia congenita. PC type 1, the Jadassohn-Lewandowsky type, shows oral leukokeratosis. PC type 2, the Jackson-Lawler type, has natal teeth and epidermoid cysts (cylindromas), but no oral leukoplakia. Corneal dystrophy may be a feature exclusively of the Jackson-Lawler type.
Smith et al. (1998) stated that PC type 2, in contrast to PC type 1, has minimal oral involvement and milder keratoderma, and multiple steatocystomas (184500) is a major clinical feature. Steatocystoma, also known as eruptive vellus cyst, is a cystic hamartoma lined by sebaceous ductal epithelium.
On the basis of a study of 13 patients with PC type 1 or type 2, Terrinoni et al. (2001) concluded that the presence of pilosebaceous cysts following puberty is the best indicator of PC type 2; prepubescent patients are more difficult to classify due to the lack of cysts. Natal teeth are indicative of PC type 2, although their absence does not preclude the PC type 2 diagnosis.
Genetic Heterogeneity of Pachyonychia Congenita
See pachyonychia congenita-2 (PC2; 167210), caused by mutation in the KRT17 gene (148069) on chromosome 17; PC3 (615726), caused by mutation in the KRT6A gene (148041) on chromosome 2; and PC4 (615728), caused by mutation or in the KRT6B gene (148042) on chromosome 12.
See 260130 for a possible autosomal recessive form of pachyonychia congenita.
The form of PC caused by mutation in the KRT16 gene, here designated PC1, has also been designated PC-16 (Eliason et al., 2012) and PC-K16 (Shah et al., 2014).
Pachyonychia congenita is characterized by oral leukokeratosis, onychogryposis, hyperkeratosis of the palms and soles, follicular keratosis, especially of the knees and elbows, and hyperhidrosis of the hands and feet. Occasionally dystrophic changes are also observed in the hair or cornea (Witkop and Gorlin, 1961).
Laryngeal changes requiring tracheostomy for respiratory distress during childhood were reported by Stieglitz and Centerwall (1983) in father and son. Feinstein et al. (1988) classified 168 reported cases into 4 types, of which type IV, present in 7.2% of the cases, had laryngeal lesions, hoarseness, mental retardation, hair anomalies, and alopecia.
Leachman et al. (2005) analyzed clinical, pathologic, and genetic data from the literature in 2 research registries. They found that more than 97% of PC cases exhibited fingernail and toenail thickening, and painful plantar keratoderma. Prospective evaluation of 57 PC patients from 41 families revealed variable clinical findings: hyperhidrosis (79%), oral leukokeratosis (75%), follicular keratosis (65%), palmar keratoderma (60%), cutaneous cysts (35%), hoarseness or laryngeal involvement (16%), coarse or twisted hair (26%), early primary tooth loss (14%), and presence of natal or prenatal teeth (2%). Stratification of these data by keratin mutation confirmed the increased incidence of cyst formation and natal teeth among PC2 patients, although cysts were more commonly seen in PC1 patients than had previously been reported (25-33%). Previously unreported clinical features of PC included development of painful oral and nipple lesions during breastfeeding, copious production of waxy material in ears, and inability to walk without an ambulatory aid (50%).
Pachyonychia Congenita, Late-Onset
Pachyonychia congenita with late onset of symptoms has been described by several authors (Paller et al., 1991; Iraci et al., 1993; Lucker and Steijlen, 1995; Mouaci-Midoun et al., 1996; Hannaford and Stapleton, 2000) and has been referred to as pachyonychia congenita tarda. Paller et al. (1991) described a late-onset form in which typical subungual hyperkeratoses began during the teenage years. Leukokeratosis and keratoderma of the palms and soles were associated. The family history of 3 of the 5 patients was consistent with autosomal dominant inheritance.
Connors et al. (2001) described a young girl with clinical features of pachyonychia congenita type 1 in whom the typical skin and nail changes were not noted until the age of 6 years. Direct sequencing of the KRT16 gene revealed a novel lys354 to asn mutation (K354N; 148067.0008) in the central 2B domain of the KRT16 polypeptide. Mutations in this region of KRT16 had not been described, but had been described in homologous regions of KRT14 (148066) in the milder Koebner (131900) and Weber-Cockayne (131800) variants of epidermolysis simplex. It was unclear whether the position of the mutation was sufficient to explain the late-onset phenotype.
Pachyonychia congenita is inherited as an autosomal dominant trait (Gorlin et al., 1976). Murray (1921) found 7 affected in 3 generations. Kumer and Loos (1935) found 24 affected in 5 generations. McKusick (1971) observed an apparent new mutation with transmission from father to son in a Jewish family.
Prenatal Diagnosis
Using a genomic PCR system, Smith et al. (1999) carried out the first prenatal diagnosis of Jadassohn-Lewandowsky syndrome using CVS material, correctly predicting a normal fetus.
In a sporadic case of pachyonychia congenita-1, described as the Jadassohn-Lewandowsky type, McLean et al. (1995) identified heterozygosity for a missense mutation (L132P; 148067.0001) in the helix initiation motif of KRT16.
In affected members of a 5-generation Dutch family with the Jadassohn-Lewandowsky type of PC, Smith et al. (1999) identified heterozygosity for a missense mutation (R127P; 148067.0005) in the KRT16 gene. In a sporadic case of pachyonychia congenita-1, they identified heterozygosity for a 3-bp deletion in KRT16 (148067.0004).
Smith et al. (2005) identified keratin mutations in 30 probands from the International Pachyonychia Congenita Research Registry, including 8 patients with mutations in the KRT16 gene (see, e.g., 148067.0001-148067.0003 and 148067.0012). Smith et al. (2005) noted that the probands from 2 families with the same mutation, N125S (148067.0003), had different phenotypes: 1 proband, who had complete lack of thickening and only minor splinter hemorrhages of the nails, was given a diagnosis of FNEPPK (613000), whereas the other proband had typical hypertrophic dystrophy involving 17 of 20 nails. The authors suggested that in keratin disorders, a combination of factors, genetic and environmental, might be involved in determining the overall clinical phenotype.
In a 36-year-old Chinese woman with severe hypertrophic dystrophy of the toenails and diffuse painful plantar keratoderma, with subtle focal palmar hyperkeratoses and normal nails of the hands, Du et al. (2012) identified heterozygosity for a KRT16 missense mutation (N125G; 148067.0013). Her 5-year-old daughter, who had only focal plantar hyperkeratosis at pressure points, without nail or hand involvement, was also heterozygous for the mutation. Both patients reported hyperhidrosis of the hands and feet. The mutation was not found in unaffected family members or in 100 controls.
Samuelov et al. (2020) analyzed 815 individuals with confirmed keratin mutations registered in the International Pachyonychia Congenita Research Registry to delineate clinical features and phenotype-genotype correlations. Mutations in KRT6A and KRT16 were the most common (41% and 31%, respectively). Mutations in KRT6B accounted for 9% of PC patients. Young age at diagnosis or involvement of a high number of fingernails and toenails was significantly associated with PC3. Plantar keratoderma was seen in all PC patients; however, palmar keratoderma was most common in PC1. Oral leukokeratosis, nursing difficulties, hoarseness, and ear pain/ear wax were significantly associated with PC3. Cysts and natal teeth were most commonly seen in PC2. Natal teeth were not reported in either PC1 or PC4. Lack of fingernail involvement was most commonly seen in PC1 and PC4.
Lessard and Coulombe (2012) generated Krt16 -/- mice and observed failure to thrive and increased postnatal mortality, with more than 30% of mice dying within 24 hours of birth and over 60% before weaning age. The survivors continued to grow and gained weight but remained smaller and lighter than their littermate controls. Hyperplastic lesions on the dorsal midline posterior tongue were observed in all mutant mice by postnatal day 3 (P3). Surviving mice no longer had visible lesions, but tongue architecture showed thickened epithelium and loss of normal filiform papillae; the authors suggested that the oral lesions might be painful and affect feeding behavior. Starting at 4 to 6 weeks of age, Krt16 -/- mice developed prominent hyperkeratotic calluses of both the front and hind paws, particularly in areas of high physical impact, consistent with the KRT16-associated focal PPK observed in humans. Adult mutant mice were significantly less active than control animals, which the authors hypothesized was the result of substantial discomfort due to the palmoplantar lesions. Reduced filaggrin expression in established front paw calluses was observed, indicating focal loss of barrier protection. In contrast to human disease, nail morphology was not affected in Krt16 -/- mice.
Akesson, H. O. Pachyonychia congenita in six generations. Hereditas 58: 103-110, 1967. [PubMed: 5586605]
Bowden, P. E., Haley, J. L., Kansky, A., Rothnagel, J. A., Jones, D. O., Turner, R. J. Mutation of a type II keratin gene (K6a) in pachyonychia congenita. Nature Genet. 10: 363-365, 1995. [PubMed: 7545493] [Full Text: https://doi.org/10.1038/ng0795-363]
Cohn, A. M., McFarlane, J. F., Knox, J. Pachyonychia congenita with involvement of the larynx. Arch. Otolaryng. 102: 233-235, 1976. [PubMed: 1267708] [Full Text: https://doi.org/10.1001/archotol.1976.00780090075011]
Connors, J. B., Rahil, A. K., Smith, F. J. D., McLean, W. H. I., Milstone, L. M. Delayed-onset pachyonychia congenita associated with a novel mutation in the central 2B domain of keratin 16. Brit. J. Derm. 144: 1058-1062, 2001. [PubMed: 11359398] [Full Text: https://doi.org/10.1046/j.1365-2133.2001.04199.x]
Du, Z.-F., Xu, C.-M., Zhao, Y., Liu, W.-T., Chen, X.-L., Chen, C.-Y., Fang, H., Ke, H.-P., Zhang, X.-N. Two novel de novo mutations of KRT6A and KRT16 genes in two Chinese pachyonychia congenita pedigrees with fissured tongue or diffuse plantar keratoderma. Europ. J. Derm. 22: 476-480, 2012. [PubMed: 22668561] [Full Text: https://doi.org/10.1684/ejd.2012.1773]
Eliason, M. J., Leachman, S. A., Feng, B., Schwartz, M. E., Hansen, C. D. A review of the clinical phenotype of 254 patients with genetically confirmed pachyonychia congenita. J. Am. Acad. Derm. 67: 680-686, 2012. [PubMed: 22264670] [Full Text: https://doi.org/10.1016/j.jaad.2011.12.009]
Feinstein, A., Friedman, J., Schewach-Millet, M. Pachyonychia congenita. J. Am. Acad. Derm. 19: 705-711, 1988. [PubMed: 3053803] [Full Text: https://doi.org/10.1016/s0190-9622(88)70226-1]
Franzot, J., Kansky, A., Kavcic, S. Pachyonychia congenita (Jadassohn-Lewandowsky syndrome): a review of 14 cases in Slovenia. Dermatologica 162: 462-472, 1981. [PubMed: 6456161]
Gorlin, R. J., Pindborg, J. J., Cohen, M. M., Jr. Syndromes of the Head and Neck. (2nd ed.) New York: McGraw-Hill (pub.) 1976. Pp. 600-603.
Hannaford, R. S., Stapleton, K. Pachyonychia congenita tarda. Australas. J. Derm. 41: 175-177, 2000. [PubMed: 10954990] [Full Text: https://doi.org/10.1046/j.1440-0960.2000.00425.x]
Iraci, S., Bianchi, L., Gatti, S., Carrozzo, A. M., Bettini, D., Nini, G. Pachyonychia congenita with late onset of nail dystrophy--a new clinical entity? Clin. Exp. Derm. 18: 478-480, 1993. [PubMed: 8252777] [Full Text: https://doi.org/10.1111/j.1365-2230.1993.tb02257.x]
Jadassohn, J., Lewandowsky, F. Pachyonychia congenita. In: Jacobs Ikonographia Dermatologica. Vol. 1. Berlin: Urban and Schwarzenberg (pub.) 1906. P. 29.
Joseph, H. L. Pachyonychia congenita. Arch. Derm. 90: 594-603, 1964. [PubMed: 14206866] [Full Text: https://doi.org/10.1001/archderm.1964.01600060060011]
Kumer, L., Loos, H. O. Ueber Pachyonychia congenita (Typus Riehl). Wien. Klin. Wschr. 48: 174-178, 1935.
Leachman, S. A., Kaspar, R. L., Fleckman, P., Florell, S. R., Smith, F. J. D., McLean, W. H. I., Lunny, D. P., Milstone, L. M., van Steensel, M. A. M., Munro, C. S., O'Toole, E. A., Celebi, J. T., Kansky, A., Lane, E. B. Clinical and pathological features of pachyonychia congenita. J. Invest. Derm. Symp. Proc. 10: 3-17, 2005. [PubMed: 16250204] [Full Text: https://doi.org/10.1111/j.1087-0024.2005.10202.x]
Lessard, J. C., Coulombe, P. A. Keratin 16-null mice develop palmoplantar keratoderma, a hallmark feature of pachyonychia congenita and related disorders. J. Invest. Derm. 132: 1384-1391, 2012. [PubMed: 22336941] [Full Text: https://doi.org/10.1038/jid.2012.6]
Lucker, G. P. H., Steijlen, P. M. Pachyonychia congenita tarda. Clin. Exp. Derm. 20: 226-229, 1995. [PubMed: 7671418] [Full Text: https://doi.org/10.1111/j.1365-2230.1995.tb01307.x]
McKusick, V. A. Pachyonychia congenita in father and son. Birth Defects Orig. Art. Ser. VII(8): 274-275, 1971. [PubMed: 5173283]
McLean, W. H. I., Hansen, C. D., Eliason, M. J., Smith, F. J. D. The phenotypic and molecular genetic features of pachyonychia congenita. J. Invest. Derm. 131: 1015-1017, 2011. [PubMed: 21430705] [Full Text: https://doi.org/10.1038/jid.2011.59]
McLean, W. H. I., Rugg, E. L., Lunny, D. P., Morley, S. M., Lane, E. B., Swensson, O., Dopping-Hepenstal, P. J. C., Griffiths, W. A. D., Eady, R. A. J., Higgins, C., Navsaria, H. A., Leigh, I. M., Strachan, T., Kunkeler, L., Munro, C. S. Keratin 16 and keratin 17 mutations cause pachyonychia congenita. Nature Genet. 9: 273-278, 1995. [PubMed: 7539673] [Full Text: https://doi.org/10.1038/ng0395-273]
Mouaci-Midoun, N., Cambiaghi, S., Abimelec, P. Pachyonychia congenita tarda. J. Am. Acad. Derm. 35: 334-335, 1996. [PubMed: 8698920] [Full Text: https://doi.org/10.1016/s0190-9622(96)90663-5]
Murray, F. A. Congenital anomalies of the nails: four cases of hereditary hypertrophy of the nail bed associated with a history of erupted teeth at birth. Brit. J. Derm. 33: 409-412, 1921.
Paller, A. S., Moore, J. A., Scher, R. Pachyonychia congenita tarda: a late-onset form of pachyonychia congenita. Arch. Derm. 127: 701-703, 1991. [PubMed: 1827243]
Samuelov, L., Smith, F. J. D., Hansen, C. D., Sprecher, E. Revisiting pachyonychia congenita: a case-cohort study of 815 patients. Brit. J. Derm. 182: 738-746, 2020. [PubMed: 31823354] [Full Text: https://doi.org/10.1111/bjd.18794]
Shah, S., Boen, M., Kenner-Bell, B., Schwartz, M., Rademaker, A., Paller, A. S. Pachyonychia congenita in pediatric patients: natural history, features, and impact. JAMA Derm. 150: 146-153, 2014. [PubMed: 24132595] [Full Text: https://doi.org/10.1001/jamadermatol.2013.6448]
Smith, F. J. D., Jonkman, M. F., van Goor, H., Coleman, C. M., Covello, S. P., Uitto, J., McLean, W. H. I. A mutation in human keratin K6b produces a phenocopy of the K17 disorder pachyonychia congenita type 2. Hum. Molec. Genet. 7: 1143-1148, 1998. [PubMed: 9618173] [Full Text: https://doi.org/10.1093/hmg/7.7.1143]
Smith, F. J. D., Liao, H., Cassidy, A. J., Stewart, A., Hamill, K. J., Wood, P., Joval, I., van Steensel, M. A. M., Bjorck, E., Callif-Daley, F., Pals, G., Collins, P., Leachman, S. A., Munro, C. S., McLean, W. H. I. The genetic basis of pachyonychia congenita. J. Invest. Derm. Symp. Proc. 10: 21-30, 2005. [PubMed: 16250206] [Full Text: https://doi.org/10.1111/j.1087-0024.2005.10204.x]
Smith, F. J. D., McKusick, V. A., Nielsen, K., Pfendner, E., Uitto, J., McLean, W. H. I. Cloning of multiple keratin 16 genes facilitates prenatal diagnosis of pachyonychia congenita type 1. Prenatal Diag. 19: 941-946, 1999. [PubMed: 10521820]
Stieglitz, J. B., Centerwall, W. R. Pachyonychia congenita (Jadassohn-Lewandowsky syndrome): a seventeen-member, four-generation pedigree with unusual respiratory and dental involvement. Am. J. Med. Genet. 14: 21-28, 1983. [PubMed: 6829608] [Full Text: https://doi.org/10.1002/ajmg.1320140105]
Sybert, V. P. Genetic Skin Disorders. (2nd ed.) New York: Oxford Univ. Press (pub.) 2010. Pp. 248-253.
Terrinoni, A., Smith, F. J. D., Didona, B., Canzona, F., Paradisi, M., Huber, M., Hohl, D., David, A., Verloes, A., Leigh, I. M., Munro, C. S., Melino, G., McLean, W. H. I. Novel and recurrent mutations in the genes encoding keratins K6a, K16 and K17 in 13 cases of pachyonychia congenita. J. Invest. Derm. 117: 1391-1396, 2001. [PubMed: 11886499] [Full Text: https://doi.org/10.1046/j.0022-202x.2001.01565.x]
Witkop, C. J., Jr., Gorlin, R. J. Four hereditary mucosal syndromes. Arch. Derm. 84: 762-771, 1961. [PubMed: 14007732] [Full Text: https://doi.org/10.1001/archderm.1961.01580170056008]