Pachyonychia congenita (PC) is a rare genodermatosis affecting the nails, skin, oral mucosae, larynx, hair, and teeth. Pathogenic mutations in keratins K6a or K16 are associated with the PC-1 phenotype whereas K6b and K17 mutations are associated with the PC-2 phenotype. Analysis of clinical, pathological, and genetic data from the literature and two research registries reveal that >97% of PC cases exhibit 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 PC-2 patients, although cysts were more commonly seen in PC-1 than previously reported (25%-33%). Previously unreported clinical features of PC include 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%). Possible pathogenic mechanisms are discussed with respect to the clinicopathologic and genetic correlations observed.
Pachyonychia congenita (PC) is a rare autosomal dominant condition characterized by multiple ectodermal abnormalities. Patients with Jadassohn-Lewandowsky Syndrome (MIM #167200; PC-1) have nail defects (onchyogryposis), palmoplantar hyperkeratosis, follicular hyperkeratosis and oral leukokeratosis. Those with the rarer Jackson-Lawler Syndrome (MIM #167210; PC-2) lack oral involvement but have natal teeth and cutaneous cysts. Ultra-structural studies have identified abnormal keratin tonofilaments and linkage to the keratin gene cluster on chromosome 17 has been found in PC families. Keratins are the major structural proteins of the epidermis and associated appendages and the nail, hair follicle, palm, sole and tongue are the main sites of constitutive K6, K16 and K17 expression. Furthermore, mutations in K16 and K17 have recently been identified in some PC patients. Although we did not detect K16 or K17 mutations in PC families from Slovenia, we have found a heterozygous deletion in a K6 isoform (K6a) in the affected members of one family. This 3 bp deletion (AAC) in exon 1 of K6a removes a highly conserved asparagine residue (delta N170) from position 8 of the 1A helical domain (delta N8). This is the first K6a mutation to be described and this heterozygous K6a deletion is sufficient to explain the pathology observed in this PC-1 family.
The skin disease erythrokeratoderma variabilis (EKV) has been shown to be associated with mutations in GJB3 and GJB4 encoding connexin (Cx)31 and Cx30.3, respectively. Gap junctions composed of Cx proteins are intracellular channels providing a mechanism of synchronized cellular response facilitating metabolic and electronic functions of the cell. In the skin, Cx31 and Cx30.3 are expressed in the stratum granulosum of the epidermis with a suggested role in late keratinocyte differentiation. Molecular investigations of GJB3 and GJB4 were performed in five pedigrees and three sporadic cases of EKV. Mutational analyzes revealed disease-associated Cx31 or Cx30.3 mutations in only three probands of which two were novel mutations and one was a recurrent mutation. These genetic studies further demonstrate the heterogeneous nature of the erythrokeratodermas as not all individuals that were clinically diagnosed with EKV harbor Cx31 or Cx30.3 mutations.
We report the results of patch tests with fragrance-mix as a part of the standard series carried out over the last 10 years (1989-1998) during routine testing of 6129 patients in our department. 5.9% of the total number of patients who were patch tested were positive to fragrance mix. The sex ratio was 2.3:1 with a female predominance. In 1989-1993, the frequency of contact sensitivity to fragrance mix was 3.9% (4.9% for females and 2.1% for males). This rate rose both in female and male patients during the observed period of time and attained 8.9% (females) and 4.1% (males) in 1994-1998; the overall frequency in 1994-98 was 7.5%. This rising trend, which was statistically significant, might be the consequence of an increased use of cosmetics and toiletries containing fragrances in our population.
To determine the occurrence of hereditary bullous epidermolyses (EB) in Croatia, Yugoslavia, from 1960 to 1987, cases were gathered from the hospital files of dermatologic and pediatric clinics and departments throughout the area. The diagnosis of EB type was made on the basis of clinical features, patients' histories, and light microscopy and electron microscopy findings. Fifty families with 58 patients were registered; 44 patients were examined personally by one of the authors. The most frequent type of EB in Croatia was recessive dystrophic EB Hallopeau-Siemens, occurring in 35 of the 58 individuals. Regional accumulation of cases within the Varazdin area was noted (13 patients). Prevalence of EB in Croatia is 0.956 cases per 100,000 inhabitants. One case of recessive dystrophic EB Hallopeau-Siemens occurred in about every 52,000 live births.
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