BSPD MEETING 87

5/19 (26-3%) of children, all within 3 months oftreatment. Recurring warts responded in all cases tohome application of 0-5% podophyllotoxin. Surgery/electrocautery was well tolerated; no notable side-effectsoccurred.

Electrocautery combined with surgical excision is asimple, safe and efficacious treatment of anogenitalwarts in children.

A double-blind controlled trial ofhyposensitization to the house dust mite inchildhood atopic eczema

M.T.GLOVER AND D.J.ATHERTONDepartment of Dermatology, The Hospital for Sick Children,London WCl

A double-blind controUed-trial of hyposensitization withtyrosine-adsorbed Dermatophagoides pteronyssinus vac-cine in 24 children with atopic eczema and immediatehypersensitivity to D. pteronyssinus failed to demonstratesuperiority over placebo after a standard 8-monthcourse of treatment.

In a second phase, children initially administeredactive treatment were randomly allocated to continuewith active treatment or switched to placebo for afurther 6 months. The clinical scores suggest thatprolonged hyposensitization may be more efi'ective thanplacebo (P = 0-0339) but the numbers were too small topermit confident conclusions. A dramatic placebo effectmay have served to conceal any additional therapeuticeffect from active treatment.

A microbiological study of atopic eczema

H.M.GOODYEAR, S.E.EGAN, P.J.WATSON,E.H.PRICE, P.A.KENNY AND J.I.HARPERQueen Elizabeth Hospital for Children, Ijjndon

Eifty children attending the hospital for the first timewith eczema and 20 age and sex-matched non-atopiccontrols were studied to determine the colonization ofskin and to assess the incidence of antibiotic resistance.Contact agar discs were compared with routine bacterio-logical swabs. Standardized discs were prepared usingagar in a 50-ml syringe and placed directly on the skinsurface. Samples were taken from the worst affected areaof eczema and from an uninvolved site in patients andfrom the anterior forearm in controls. Swabs were takenfrom the nose, axilla and groin in all children.

Staphylococcus aureus (SA) was the most commonpathogen, being detected on the skin in 80% of patientsbut in none of the controls. The contact agar discs werefound to be consistently more sensitive than routineswabs with > 100 SA colonies detected in 70% of thepatients using the discs, compared with 28% usingswabs from the worst-affected sites and 26% comparedwith 4% from uninvolved sites. Other bacteria isolatedwere coliforms (2), /3-haemolytic Streptococcus (1) andBacillus species (1). Carriage rates of SA in patients were20% in the nose, 12% in the axillae and 10% in thegroins. SA was detected from nasal swabs in 10% of thecontrols but not from the other sites. Phage types of SAwere 55 (9), 71 (8), 3A (6), 3C (6), 29 (5), 53 (5) and 75(4). Twenty-seven stains were not typable. SA strainswere resistant to penicillin in 88% of cases and tomultiple antibiotics in 38% of cases.

The importance of these findings is discussed inrelation to the management of atopic eczema.

A novel diagnostic test for incontinentiapigmenti

C.MOSS AND J.GOODSHIPDepartments of Dermatology and "Clinical Genetics.Royal Victoria Infirmary, Newcastle upon Tyne

A 10-year-old girl and her mother were referred fordiagnosis and genetic counselling. The girl was pro-foundly retarded with intractable epilepsy and severehypotonia. She had bilateral dislocated hips, downwardsloping palpebral fissures, fine skin, sparse hair, andpigmented streaks around the left chest and along theposterior thighs. Her teeth were normal and there wasno history of vesicular or verrucous lesions. There wasno relevant family history; in particular her mother wasnormal on examination. Possible diagnoses includedatypical incontinentia pigmenti (IP) and linear dyspig-mentation due to chromosomal mosaicism. However,cytogenetic studies with particular attention to thepossible IP loci at Xpl 1.21 and Xq28 showed a normal46XX karyotype and there was no mosaicism in 50 cellsexamined.

The distribution of skin lesions in IP has beenattributed to random X-inactivation (Lyonization). How-ever, studies in affected females have shown skewedpatterns of X-inactivation with lymphocytes and fibro-blasts from both normal and affected skin predominantlyexpressing the paternal X chromosome, possibly becausecells expressing the maternal X chromosome carrying

88 BSPD MEETING

the lethal incontinentia pigmenti gene are selectivelyeliminated early on. X-inactivation studies in this familyshowed that the patient exclusively expresses the Xchromosome while her mother expresses both. Thisimplies that the patient carries a lethal X-linked genewhich in the clinical context must he IP. Her mother canbe counselled that this arose as a new mutation, with norisk of recurrence.

5. The clinical apperance ofthe scalp hair is due mainlyto the weathering.

Hair analysis in trichothiodystrophy todistinguish primary and secondary features

D.DE BERKER, J.TOLMIE* AND R.P.R.DAWBERDepartment of Dermatology, The Slade Hospital, Oxford and

'Duncan Guthrie Institute of Medical Genetics, Glasgow

Trichothiodystrophy (TTD) is a highly specific haircondition which can be found alone or as part of certainsevere neuroectodermal syndromes. Deficient sulphurincorporation into the hair, with distinctive hair micro-scopic findings, provides a characteristic (usually diag-nostic) sign. In many dermatological, paediatric andgenetic textbooks the primary and secondary changes inthe hair are not differentiated. The instrinsic hairchanges said to be specific to TTD are often confused withthe secondary acquired weathering which can varyconsiderably from case to case.

During the last 10 years we have seen 14 cases of thiscondition and noted a considerable range of clinical andmicroscopic hair findings. We have carried out thefollowing investigations of scalp hair to characterize thedefect: transmitted and polarizing light microscopy,scanning electron microscopy and transmission electronhistochemistry. From these we draw the followingconclusions.

1. The intrinsic defect is due to the failure of incorpora-tion of sulphur-rich protein into the cuticle andmatrix of the hair cortex.

2. The 'zigzag' pattern seen with polarized light is notalways present, even in severe cases.

3. The hair shafts weather prematurely due mainly tothe failure of migration ofthe sulphur-rich protein tothe outer surface of each cuticle cell, i.e. there isdeficient exocuticle and A-layer which normallyprotect against weathering.

4. Because of this, weathering begins very proximallyon the hair shaft in the cuticle leading to non-specifictrichoschisis, trichorrhexis nodosa and fracture.

Linkage analysis of Weber-Cockayneepidermolysis bullosa simplex

K.E.MCKENNA, A.E.HUGHES, W.H.I.MCLEANAND N.C.NEVINDepartment of Dermatology. Royal Victoria Hospital. Belfast and

Department of Medical Genetics. The Queen's University of Belfast.

Belfast City Hospital

Epidermolysis bullosa is a heterogeneous group ofgenetic disorders which can be subdivided into thesimplex, junctional and dystrophic classes. The simplexform (EBS) is characterized by intraepidermal blisterswhich heal without scarring. Weber-Cockayne EBS(with generalized blistering) both show autosomal domi-nant inheritance. Pooled data from Weber-Cockayneand Kobner EBS families has suggested tentative looselinkage to the Duffy (Fy) blood group locus on chromo-some lq. Recently a Kobner EBS family from Ireland hasbeen reported to show linkage to the antithrombin IIIgene (AT3) locus at Iq23-q25.' We have tested aNorthern Irish Weber-Cockayne EBS family for possiblelinkage to this region of chromosome 1. Polymorphismswere typed using DNA probes on Southern blots or bypolymerase chain-reaction amplification and agarose orpolyacrylamide gel electrophoreses. Analysis of haplo-types of three polymorphisms within the AT3 geneexcluded close linkage to this locus (z<—2 at 0 = 0-10).Typing of Fy blood group suggested possible linkage(Zmax=l"01 at 0 = 0-01). However, this is discounted onthe basis of non-linkage to the more informative MUCand AP0A2 loci which are thought to flank the Fy geneand also to the SPTAl locus (MUC Z < - 2 at 0 = 0-07;AP0A2 Z< - 2 at 0 = 0-08).

These results indicate that the gene causing Weber-Cockayne EBS in this family does not lie between theMUC and AT3 loci on chromosome lq. Linkage distal tothe AT3 gene is being coasidered. There is also thepossibility of genetic heterogeneity between the Weber-Cockayne and Kobner varieties of EBS.

Reference1 Humphries MM et al. Epidermolysis bullosa: evidence for linkage to

genetic markers on chromosome 1 in a family with the autosomal

dominant simplex form. Genomics 1990: 7: 377-81.