Kirsti-Maria Niemi

Assignment of a Novel Locus for Autosomal Recessive Congenital Ichthyosis to Chromosome 19p13.1-p13.2

Autosomal recessive congenital ichthyosis (ARCI) is a rare, clinically and genetically heterogeneous genodermatosis. One gene (transglutaminase 1, on 14q11) and one additional locus (on 2q33-35, with an unidentified gene) have been shown to be associated with a lamellar, nonerythrodermic type of ARCI. We performed a genomewide scan, with 370 highly polymorphic microsatellite markers, on five affected individuals from one large Finnish family with nonerythrodermic, nonlamellar ARCI. The only evidence for linkage emerged from markers in a 6.0-cM region on chromosome 19p13.1-2. The maximum two-point LOD score of 7.33 was obtained with the locus D19S252, and multipoint likelihood calculations gave a maximum location score of 5.2. The affected individuals share two common core haplotypes, which makes compound heterozygosity possible. The novel disease locus is the third locus linked to ARCI, supporting previous evidence for genetic heterogeneity of ARCI. This is also the first locus for a nonlamellar, nonerythrodermic phenotype of ARCI.

Recessive ichthyosis congenita type II

SummaryIn the hetereogeneous group of recessive congenital ichthyoses the disorder of desquamation seems to be a basic problem. Desquamation is strongly dependent on the normal lipid metabolism of the keratinocytes. We describe a group of patients who have a typical clinical picture of large scale ichthyosis and cholesterol clefts in the thickened corneal layer, evidencing a disturbance of the lipid metabolism of the skin. The corneocytes also show a thin or absent cornified envelope, which could indicate a disturbance of protein synthesis. These patients have a severe ichthyosis, but good general health and no associated symptoms. This disorder has recently been named ‘ichthyosis congenita type II’ by the Heidelberg group on the basis of electron microscopic findings. According to the present examination this group corresponds clinically to the currently used diagnosis ‘lamellar ichthyosis’.

Recessive ichthyosis congenita type IV

Two patients suffering from ichthyosis with unusual ultrastructural features were examined. One was a 14-year-old boy with ichthyotic skin since birth. The ichthyosis was initially erythrodermic and later presented as follicular hyperkeratosis. The other patient was an ichthyotic child who died 2 days after birth of respiratory distress syndrome. Although apparently not consanguineous, both families came from the same relatively isolated rural area and autosomal recessive inheritance seems likely. Light microscopy did not yield diagnostic features, but the ultrastructural findings in the granular and horny cells showed diagnostic lamellar membrane packages. Identical ultrastructural features have previously been published in one prematurely born baby who died soon after birth and once in a prenatal diagnosis in the same family; the disease was termed “ichthyosis congenita type IV.”

Epidermodysplasia verruciformis. Clinical and light-and electron-microscopic observations during etretinate therapy

SummaryThree patients with epidermodysplasia verruciformis (EV) were treated with etretinate for 9–13 months. The patients had lesions characteristic of EV, including flat warts, common genital warts, pityriasis-versicolor-like lesions and malignant changes such as actinic keratosis and Bowenoid cancer in situ. During etretinate treatment, some flattening of the warts was observed in all three patients, and the lesions on the chest and back became less red and scaling. However, none of the lesions disappeared completely, and when the treatment was discontinued, the lesions relapsed. No malignant changes were detected during the period of therapy. Electron microscopy revealed the presence of typical large, clear cells containing viral particles in the upper epidermis. Etretinate therapy induced the same type of fine-structural changes as those seen in keratinization disorders and genodermatoses. The clear cells and virus particles persisted throughout the treatment period. More long-term, controlled studies are necessary to make possible an estimate of the curative and cancer-inhibitory effect of etretinate treatment in patients with EV.

Clinical, light and electron microscopic features of recessive congenital ichthyosis type I

Summary Based on electron microscopic features, recessive congenital ichthyoses have recently been divided into four subgroups designated ichthyosis congenita (IC) types I, II, III and IV, Type II is characterized by cholesterol clefts in the horny cells, type III by perinuclear elongated membranes in the granular and horny cells, and type IV by masses of lipid membranes in granular and horny cells. Clear electron microscopic criteria for type I are lacking, although the presence of lipid droplets in the horny cells has been suggested as a criterion. In the present study we included ichthyosis patients with (i) recessive inheritance, (ii) erythrodermic fine scaling, (iii) lack of line structural markers of IC types II‐IV, Patients with ichthyotic syndromes were excluded. The case material consisted of 21 patients from 14 families. Eight were collodion babies at birth, but three were normal. Nine had ectropion, the flexures were affected in 12, and the palms and soles were thickened in all but one patient. On electron microscopy lipid vacuoles in the horny cells were common, but were absent in four patients. Changes in other lipid‐related structures, including keratinosomes, were common. We conclude that currently type I can be diagnosed only by excluding the other types of ichthyosis. Clinically, IC type I corresponds to classical non‐bullous congenital ichthyosiform erythroderma, but there is marked heterogeneity among affected individuals.

Altered keratin expression in ichthyosis hystrix Curth-Macklin

SummaryThe pathogenesis of a rare form of the ichthyotic diseases, ichthyosis hystrix Curth-Macklin, was investigated by immunohistochemistry and electron microscopy. Monoclonal antibodies (Mabs) against keratins expressed in normal basal cells (PKK2 and KA1), Mabs against keratins only present in normal fetal skin (PKK1), and Mabs against keratins 1, 2, 10, and 11 (KA5 and K8.60) were used. The Mabs reacting with normal basal cells showed an increased reaction with many cell layers. The Mab PKK1 distinctly reacted with the basal cell layer, suggesting an expression of fetal keratins. Electron microscopic study of both normal-looking and involved skin revealed the keratinization disorder characterized by tonofilament shells, perinuclear vacuoles, and binuclear keratinocytes. The results suggest that there is no prematurity of keratinization, but rather a pathological expression of specific keratin genes leading to expression of fetal keratins in this form of ichthyosis hystrix.

Deletion 3q27→3qter in an infant with mild dysmorphism, parietal meningocele, and neonatal miliaria rubra-like lesions

SummaryDeletion 3q27→3qter in an infant is described. A chromosomal abnormality was suspected because of minor facial dysmorphism and closed parietal meningocele. On the first day of life, a large exudative inflammation appeared on the skin of her back, which completely resolved after 1 week. Biopsy showed dilated sweat gland openings resembling miliaria rubra, which has not been previously reported in this age group. It is unclear if the skin change was due to the chromosomal abnormality. The meningocele was repaired at age 8 months. At age 20 months, slight neurodevelopmental delay was evident, the main features being hypertonicity and inability to walk without support. The patient has two healthy sisters, and prometaphase chromosome studies in both parents were normal. This infant represents the first example of del3q27→3qter and the first reported association of meningocele with an abnormality of chromosome 3.

Clinical, light and electron microscopic features of recessive ichthyosis congenita type III.

SummaryThe recessively inherited congenital ichthyoses have ultrastructural features which indicate abnormal epidermal lipid metabolism. The ultrastructural markers of the three recessive congenital ichthyosis groups are lipid droplets in horny layers (type I), cholesterol clefts (type II) and membrane structures (type III). We describe six patients from five families belonging to the last group. The variable clinical phenotype alone does not allow the delineation of this disease, but together with the ultrastructural characteristics the subtype is unequivocal. In addition to the membrane structures, half of the cases showed abnormal keratinosomes and vesicular complexes. Membrane-bound vacuoles and needle-like slits were exceptionally found. The onset of the ichthyosis was variable, in contrast to other patients described under the heading recessive congenital ichthyosis.

Ultrastructural features resembling those of harlequin ichthyosis in patients with severe congenital ichthyosiform erythroderma.

Congenital ichthyoses are a group of heterogeneous disorders of cornification. Autosomal recessive congenital ichthyosis (ARCI) can be clinically subdivided into congenital ichthyosiform erythroderma and lamellar ichthyosis. Ultrastructurally, ARCI is classified into four groups: ichthyosis congenita (IC) types I–IV. The genetic background of the ARCI disorders is heterogeneous, but only one disease gene, transglutaminase 1, has been detected so far. We describe six patients with severe congenital ichthyosis from six different Scandinavian families. They could not be classified ultrastructurally into the four IC groups because of atypical findings of electron microscopy. These included abnormal lamellar bodies, alterations in keratohyalin, remnant organelles and lipid inclusions in the upper epidermal cells, which resembled the ultrastructural findings of harlequin ichthyosis (HI), although the HI phenotype was not present at birth. Some clinical features, such as thick scales, erythroderma, alopecia and ectropion were common to all patients. Ichthyosis was usually accentuated in the scalp and four patients had clumped fingers and toes. None of the patients carried the transglutaminase 1 mutation. We conclude that ultrastructural findings resembling those detected in previous HI cases (type 1 and 2) can also be found in patients who do not have classic clinical features of that rare ichthyosis. This may be due to lack of specificity of ultrastructural markers for HI or to its clinical heterogeneity.

Histological and ultrastructural study of a family with erythrokeratodermia progressiva symmetrica

We have examined a family with 4 members in three succeeding generations suffering from a severe keratinization disorder. The clinical phenotype, with symmetric plaques on the extremities, corresponded to erythrokeratodermia progressiva symmetrica. It was manifested at birth, however, and in addition to the hyperkeratotic plaques, follicular hyperkeratosis was also observed. Electron microscopy revealed multiple morphological changes such as myelinated membrane structures, or needles, which were similar to those occurring in ichthyotic disorders and tyro sinemia, as well as in harlequin fetuses, all of which were excluded clinically or biochemically in our patients.