HLA typing in actinic prurigo

Associations between human leukocyte antigens and renal function

Human leukocyte antigens (HLA) have been associated with renal function, but previous studies report contradictory findings with little consensus on the exact nature or impact of this observation. This study included 401,307 white British subjects aged 39–73 when they were recruited by UK Biobank. Subjects’ HLA types were imputed using HLA*IMP:02 software. Regression analysis was used to compare 362 imputed HLA types with estimated glomerular filtration rate (eGFR) as a primary outcome and clinical indications as secondary outcome measures. 22 imputed HLA types were associated with increased eGFR (and therefore increased renal function). Decreased eGFR (decreased renal function) was associated with 11 imputed HLA types, seven of which were also associated with increased risk of end-stage renal disease and/or chronic kidney disease. Many of these HLA types are commonly inherited together in established haplotypes, for example: HLA-A*01:01, B*08:01, C*07:01, DRB1*03:01, DQB1*02:01. This haplotype has a population frequency of 9.5% in England and each allele was associated with decreased renal function. 33 imputed HLA types were associated with kidney function in white British subjects. Linkage disequilibrium in HLA heritance suggests that this is not random and particularly affects carriers of established haplotypes. This could have important applications for the diagnosis and treatment of renal disease and global population health.

Human leukocyte antigen associations with renal function among ethnic minorities in the United Kingdom

Human leukocyte antigens (HLA) have been associated with renal function, but previous studies report contradictory findings. There has been a lack of research into how HLA affects renal function in Black, Asian and Minority Ethnic (BAME) people in the UK, despite BAME people being disproportionately affected by renal dysfunction. This study included >27 000 UK Biobank subjects of six ethnicities (>12 100 Irish, >5400 Indian, >4000 Black Caribbean, >3000 Black African, >1600 Pakistani, and >1400 Chinese) aged 39 to 73. Subjects' high-resolution HLA genotypes were imputed using HLA*IMP:02 software. Regression analysis was used to compare 108 imputed HLA alleles with two measures of estimated glomerular filtration rate (eGFR): one based on serum creatinine; one based on serum cystatin. Secondary analysis compared CKD stage 2 subjects to healthy controls. Nine imputed HLA alleles were associated with eGFR (adjusted P < .05). Six associations were based on creatinine in Black African subjects: HLA-B*53:01 (beta = -2.628, adjusted P = 4.69 × 10^-4 ); C*04:01 (beta = -1.667, adjusted P = .0269); DPA1*02:01 (beta = -1.569, adjusted P = .0182); and DPA1*02:02 (beta = -1.716, adjusted P = .0251) were linked to decreased renal function, while DRB1*03:01 (beta = 3.200, adjusted P = 3.99 × 10^-3 ) and DPA1*01:03 (beta = 2.276, adjusted P = 2.31 × 10^-5 ) were linked to increased renal function. Two of these (HLA-B*53:01 and C*04:01) are commonly inherited together. In Irish subjects, HLA-DRB1*04:01 (beta = 1.075, adjusted P = .0138) was linked to increased eGFR (based on cystatin); in Indian subjects, HLA-DRB1*03:01 (beta = -1.72, adjusted P = 4.78 × 10^-3 ) and DQB1*02:01 (beta = -1.755, adjusted P = 2.26 × 10^-3 )were associated with decreased eGFR (based on cystatin). No associations were found in the other three ethnic groups. Nine HLA alleles appear to be associated with kidney function in BAME people in the UK. This could have applications for the diagnosis and treatment of renal disease and could help reduce health inequalities in the UK.

Recent Developments in the Diagnosis and Management of Photosensitive Disorders

Photodermatoses occur in males and females of all races and ages. Onset can be variable in timing and influenced by genetic and environmental factors. Photodermatoses are broadly classified as immunologically mediated, chemical- and drug-induced, photoaggravated, and genetic (defective DNA repair or chromosomal instability) diseases. Advances in the field have led to improved recognition and treatment of many photodermatoses. The purpose of this focused review is to provide an update on the diagnosis and management of a variety of photodermatoses, both common and less common, with review of recent updates in the literature pertaining to their diagnosis and management.

HLA-A, B, DRB1, DQA1, DQB1 alleles and haplotype frequencies in Dene and Cree cohorts in Manitoba, Canada

BACKGROUND

First Nations in the Canadian province of Manitoba have disproportionately high rates of epidemic and endemic TB. Gene polymorphisms that modulate HLA Class I and II antigens are among the risk markers for TB, along with other biologic, and social determinants of health. HLA-A, B, DRB1, DQA1, DQB1 were typed in two Manitoba First Nation indigenous groups to identify and compare the frequency of gene polymorphisms that may influence susceptibility or resistance to TB.

METHODS

Participants who self-identified as either Dene or Cree enrolled into the study from two First Nation communities in Manitoba, Canada. Genomic DNA was extracted from blood samples collected with informed consent from Dene (N=63) and Cree (N=42) First Nation study participants. Participants self-reported having treated active TB, treated latent TB or no TB. HLA Class I and II molecules were typed using sequence-specific oligonucleotide (SSO) probes from commercially available kits.

RESULTS

The rates of treated active and latent TB were marginally higher among the Dene than the Cree participants (p=0.112). Class I and II HLA loci were in Hardy-Weinberg equilibrium in both the Dene and Cree groups. In this exploratory analysis of TB and HLA allele frequencies in Dene and Cree cohorts HLA-A*03 and HLA-DQB1*05:03 were significantly associated with TB.

CONCLUSIONS

The high incidence of TB in both Dene and Cree populations in Canada requires both biomedical and socioeconomic prevention and control measures. Among the former, an understanding of HLA diversity among First Nations groups may aid the development of new effective vaccine and therapeutic modalities that depend on the interaction between small molecules and specific HLA epitopes.

Actinic Prurigo in Singaporean Chinese: A Positive Association with HLA-DRB1*03:01

Studies have reported the association of human leukocyte antigen (HLA) genes with susceptibility to develop actinic prurigo (AP) in Caucasians, but there were no studies in Asian populations, including the Chinese. Our study was performed to determine if AP is associated with susceptibility or protective HLA alleles or haplotypes in Singaporean Chinese. All Chinese patients diagnosed with AP at National Skin Center, Singapore, from January 2002 to April 2015 were invited to participate in the study. Clinical data and phototesting results were collated, and HLA typing was performed. Among 14 patients included, 11 were male and the mean age was 49.6 (37.9-61.3) years. All patients did not have a family history of AP and none had mucosal involvement, as such these clinical features differed from Caucasian AP patients. The frequency of DRB1*03:01 in AP patients was significantly higher compared to healthy controls (43% vs 16%, P = 0.022, odds ratio (OR) 3.89). Concurrently, the frequency of HLA-B*58:01-DRB1*03:01 haplotype was also significantly increased (25% vs 7%, P = 0.004, OR 4.23). In conclusion, HLA-DRB1*03:01 was associated with AP in Singaporean Chinese patients. This novel allelic association may possibly be utilized as a biological marker to aid in the diagnosis of AP in Chinese patients.

Dermatology in the North American Indian/Alaska Native population

Dermatology is greatly understudied in the American Indian/Alaska Native (AIAN) population. This topic deserves attention in light of the changing demographics of the United States and the healthcare disparities faced by AIAN, including access to dermatologic care. In this review, we discuss disorders that are more prevalent or otherwise important in the AIAN population, such as cutaneous malignancies, photodermatoses, acanthosis nigricans, connective tissue disorders, cutaneous infections, hypertrophic scar formation, and Heck's disease. We aim to provide an updated review and increase awareness of the dermatologic needs of the AIAN population.

Actinic prurigo

Actinic prurigo is a chronic photodermatosis with onset in childhood or before 20 years of age. It is most prevalent in Amerindians and Latin American mestizos, although it has been reported worldwide. Patients present with photodistributed, erythematous excoriated papules, cheilitis, and conjunctivitis. There is strong association with human leukocyte antigen DR4, especially the DRB1*0407 subtype. Treatment consists of photoprotection and the use of thalidomide.

Hereditäre Photodermatosen

Hereditary photodermatoses are characterized by an increased photosensitivity caused by an inherited single gene defect. With few exceptions, they manifest in early childhood, reveal heterogeneous clinical symptoms, and are difficult to treat. Although these diseases are rare, it is very important to make an accurate diagnosis on the basis of clinical symptoms, specific diagnostic tests, and direct DNA analysis. We review the spectrum of inherited photodermatoses, including porphyria cutanea tarda, erythropoietic protoporphyria, actinic prurigo, Kindler syndrome, and disorders associated with a defect in DNA repair, including xeroderma pigmentosum, trichothiodystrophy, Cockayne syndrome, and Bloom syndrome. Early diagnosis may prevent complications associated with prolonged unprotected exposure to sunlight and makes it possible to offer genetic counseling and, when indicated, prenatal diagnosis to families at risk for these rare heritable disorders.

Reticular Erythematous Mucinosis Occurring in a Brother and Sister

Reticular erythematous mucinosis (REM) is a rare, primary cutaneous mucinosis clinically characterized by a persistent reticular erythema on the mid chest and mid-upper back, and histologically by a mononuclear cell infiltrate and deposits of mucin in the dermis. To our knowledge, the present report of REM occurring in a Caucasian man and his sister is the first reported case of familial REM. Since a host-specific immune response to unknown antigens may be involved in the pathogenesis of this entity, human leukocyte antigen typing was determined and compared to those reported in autoimmune diseases.

Association of HLA subtype DRB1*0407 in Colombian patients with actinic prurigo

BACKGROUND

Human leukocyte antigen (HLA) DRB1*0407 had been associated with actinic prurigo in different populations. This class II HLA-DR subtype had not been studied in Colombia.

OBJECTIVE

The objective of this study was to establish whether there was an association of actinic prurigo with HLA DR in a Colombian population.

MATERIALS AND METHODS

Forty patients with a clinical diagnosis of actinic prurigo and 40 healthy subjects, paired by age, sex and birthplace, were studied. HLA typing for HLA DRB1 and DRB1*04, if necessary, was performed by the PCR-SSP method using blood samples.

RESULTS

A high frequency of HLA DRB1*0407 was found in the patients (97.5% vs. 30%; P<0.00001). The allelic frequency of HLA DRB1*0407 was 63.8% in the case group, and 14.5% in the controls (P<0.00001). In the control group, there was a higher frequency of the alleles DRB1*01 (14.5% vs. 1.25%; P=0.0027) and DRB1*13 (23.7% vs. 2.5%; P=0.00013).

LIMITATIONS

The small number of controls does not allow us to drive conclusions about other HLA alleles.

CONCLUSIONS

HLA subtype DRB1*0407, found in actinic prurigo patients in studies conducted in England, Scotland, Ireland and Mexico, was also associated in Colombian patients. This finding, concordant in patients from different ethnic groups, could be helpful in the diagnosis of this disease and probably important in its pathogenesis. DRB1*01 and DRB1*13 alleles were more frequent in controls than in patients; we do not know whether they play any role in the resistance to the disease.

Evidence that thalidomide modifies the immune response of patients suffering from actinic prurigo

BACKGROUND

Actinic prurigo (AP) is a photodermatosis with a restricted ethnic distribution, mainly affecting Mestizo women (mixed Indian and European). The lesions are polymorphic and include macules, papules, crusts, hyperpigmentation and lichenification. Thalidomide, an effective immunomodulatory drug, was first used successfully to treat AP in 1973. In this work we describe the effect that thalidomide had on TNF-alpha sera levels and on IL-4- and IFN gamma (IFNgamma)-producing lymphocytes of actinic prurigo (AP) patients.

METHODS

Actinic prurigo patients were analyzed before and after thalidomide treatment. The percentage of IL-4+ or IFNgamma+ CD3+ lymphocytes was analyzed in eight of them by flow cytometry. TNFalpha in sera was measured by ELISA in 11 patients.

RESULTS

A direct correlation was observed between resolution of AP lesions and an increase in IFNgamma+ CD3+ peripheral blood mononuclear cells (P < or = 0.001) and a decrease in TNFalpha serum levels (no statistical difference). No IL-4+ CD3+ cells were detected.

CONCLUSIONS

Our findings confirm that AP is a disease that has an immunological component and that thalidomide clinical efficacy is exerted not only through inhibition of TNFalpha synthesis, but also through modulation of INFgamma-producing CD3+ cells. These cells could be used as clinical markers for recovery.

Diagnosis and treatment of actinic prurigo

Actinic prurigo (AP) is an idiopathic photodermatosis that affects mainly the mestizo population in Latin America. It has an early onset, a slight predominance in women, and affects the sun-exposed areas of the skin, causing erythematous papules and lichenified plaques secondary to intense and chronic pruritus. Lesions can be induced by both ultraviolet A (UVA) and ultraviolet B (UVB). An association with several human leukocyte antigen (HLA) alleles has been reported. AP is unique among all photodermatoses in its remarkable response to thalidomide. In the past the microscopic features of AP have been considered as nonspecific; however, the constant finding of dense lymphocytic inflammatory infiltrates and the immunogenetic features of AP support the existence of an immunologic mechanism in its pathogenesis.

[Photodermatoses during childhood]

Actinic dermatitis and phototoxic and idiopathic photodermatoses occur relatively often during childhood. Photodermatoses stemming from enzyme defects and genetic disorders are much less common, while photoallergic and chronic actinic dermatitis have not been dealt with to date. A specific sensitivity of a child's skin to light is often the first manifest clinical symptom of a photodermatosis, the key is to ensure early diagnosis. However, it is often difficult to reach a diagnosis, as the lesions are barely perceptible or have even healed by the time the patient is examined. This is why photoprovocation tests are so important in diagnosing photodermatoses, particularly during childhood. In addition to early diagnosis of these illnesses and offering the appropriate treatment, it is also crucial that the parents be well informed and aware of what symptoms to look for so that they can protect their children from overexposure to UV light and thereby avoid later actinic injuries that can become as serious as malignancies.

Polymorphous light eruption

Polymorphous light eruption (PLE) is a common idiopathic photosensitivity disorder with an estimated prevalence of 10-20%. It is characterized by an intermittent skin reaction to ultraviolet (UV) radiation exposure, consisting of non-scarring pruritic erythematous papules, vesicles or plaques that develop on light-exposed skin. Despite the different morphology in different individuals, the eruption tends to have a monomorphous presentation in any single subject. The histopathological features of PLE are distinct and comprise a perivascular lymphocytic infiltrate in the dermis, subepidermal oedema and variable epidermal changes. The pathogenesis of PLE is not well known, but findings suggest that it is a delayed-type hypersensitivity reaction to one or more UV-modified cutaneous antigens. The principal action of PLE is mainly in the UVA region, although some subjects exhibit sensitivity to UVB alone or to both UVA and UVB radiation at the same time. Preventive measures in PLE include the regular use of photoprotective methods combined with graduated exposures to natural sunlight. The induction of immune tolerance by phototherapy and photochemotherapy are useful prophylactic methods in moderate to severe cases. The role of systemic agents in the management of PLE is under investigation. This article reviews the epidemiological, pathogenetic and clinical aspects of PLE and discusses recent advances in the diagnostic approach and management of this condition.

Lymphocyte subtypes and adhesion molecules in actinic prurigo: observations with cyclosporin A

BACKGROUND

Actinic prurigo is a photodermatitis in which UV light is implicated by an unknown mechanism.

METHODS

Skin biopsies of 19 patients with actinic prurigo and 11 controls were analyzed by immunohistochemistry.

RESULTS

In actinic prurigo patients, there was a significant increase in the number of CD3, CD4, CD8, CD45RA, CD45RO, and CD45RB lymphocytes and Langerhans cells, as well as in the level of human leukocyte antigen-DR (HLA-DR) expression and cell adhesion molecules lymphocyte functional antigen-1 (LFA-1), intercellular adhesion molecule-1 (ICAM-1), and endothelial leukocyte adhesion molecule-1 (ELAM-1). Actinic prurigo patients were treated with cyclosporin A (CsA), and a final skin biopsy was taken after 6 months of treatment. All the cell populations and markers studied, except for the CD4 lymphocytes, Langerhans cells, and HLA-DR expression, returned to normal levels.

CONCLUSIONS

CsA was found to be effective in relieving the clinical symptoms of actinic prurigo.

A case of severe actinic prurigo successfully treated with thalidomide

Actinic prurigo is an uncommon and usually persistent idiopathic photodermatosis with typical human leukocyte antigen (HLA) associations (HLA-DR4, particularly subtypes DRB1*0407 and DRB1*0401). Although its mechanism of action is not clearly understood, thalidomide has been shown to be particularly efficacious in treating actinic prurigo, among other conditions. A 31-year-old Australian woman who had suffered actinic prurigo for most of her life was treated with two courses of thalidomide (50-100 mg nocte) over consecutive summers. Remission was observed after cessation of the second course of thalidomide and had continued 4 years later. Abnormalities in the cutaneous response to ultraviolet radiation at the time of diagnosis, detected by monochromator phototesting, reverted to normal following treatment.

Actinic prurigo: Clinical features and HLA associations in a Canadian Inuit population

BACKGROUND

Actinic prurigo (AP) is an idiopathic familial photodermatitis. AP of the Inuit is rarely reported and poorly characterized.

OBJECTIVE

Our purpose was to examine the clinical features and HLA associations of AP in an Inuit population.

METHODS

Thirty-seven Inuit subjects with AP were administered a questionnaire and underwent a cutaneous examination. Other causes of photosensitivity were excluded. HLA class I typing was performed by polymerase chain reaction and sequence-specific primers and class II typing by polymerase chain reaction and sequence-specific oligonucleotide probes.

RESULTS

Subjects were 81.1% female, 67.6% had a family history of photosensitivity, and all experienced seasonal variation. The average age at onset of photosensitivity was 29 years, and only 27% had a trend toward improvement in photosensitivity. Involvement of eyes and nonexposed skin was reported in 62.2% and 18.9% of subjects, respectively. Physical examination revealed involvement of the face (64.9%), lip (32.4%), ear (13.5%), and dorsal aspect of the hand (24.3%). HLA-DRB1*14 was present in 51.2% of subjects and 26.2% of controls (P =.022, odds ratio = 2.975). This is a previously unreported HLA association.

CONCLUSION

AP in the Inuit is a seasonal, pruritic photodermatitis, often commencing in adulthood and worsening over time. A novel association with HLA-DRB1*14 has been discovered. Overall, this novel HLA association, the absence of HLA associations previously reported in non-Inuit populations, and clinical distinguishing features support the concept that AP in the Inuit may have a distinct immunopathogenic basis that translates into a different phenotype. It also raises the question of whether AP in the Inuit is a distinct photosensitivity disorder specific to this group that has been genetically isolated because of geographic and cultural seclusion.

A case of actinic prurigo in Thailand

Actinic prurigo is a separate entity from the polymorphous light eruption that affects American Indians. It has been reported mainly from North and South America, with only few reported cases from Britain or Asia. We report a case of actinic prurigo in a Thai girl who showed cheilitis and pruritic papules on exposed areas for three years. We were able to induce populovesicular lesions by three consecutive irradiations with 100 J/cm2 UVA and 2 minimal erythematous dose of UVB. However, three weeks after irradiation, a prurigo papule developed at the UVB irradiated site.

The idiopathic photodermatoses

The idiopathic photodermatoses present a challenge for dermatologists. Although, as in other specialty areas, the classical clinical presentation produces few problems, it is the severe forms and overlap cases that cause the most difficulty. It is fortunate that the semi-objective investigation of phototesting is available, which, when conducted carefully, reveals so much about the nature of this group of conditions. This essential investigation not only helps achieve a diagnosis, but also affords material for study and a means of monitoring therapy response or progress towards spontaneous resolution. Although these conditions are grouped together, throughout this century we have seen a continuing process of distinct diseases emerging as a consequence of careful clinical observation and investigation.

The clinical features and management of actinic prurigo: a retrospective study

Actinic prurigo (AP) is a rare photodermatosis, mostly affecting young American Indian girls. A retrospective descriptive study was done in the National Skin Centre, Singapore. Our patients have different characteristics compared to the previous reports. Of the 11 cases found between 1990 and 1998, 10 were male. All of the patients had the onset in adulthood. The condition was recognised by the presence of papules and nodules on the sun-exposed areas, predominantly on forearms and back of hands. Phototests revealed lowered minimal erythemal dose (MED) to ultraviolet A (UVA) alone in 2 patients and lowered MED to both UVA and UVB in another 4 patients. Patch, photopatch and histological examination did not show any significant finding. Sun protection, emollients and topical steroid were the baseline treatment for all patients. Intralesional steroid, systemic steroid, psoralen plus ultraviolet A (PUVA), azathioprine and thalidomide were used in some patients, with variable results.

Further evidence of the role of HLA-DR4 in the genetic susceptibility to actinic prurigo

BACKGROUND

Actinic prurigo (AP) is triggered by sun exposure. Its prevalence in Mexicans seems to be particularly high, which suggests a genetic susceptibility.

OBJECTIVE

Our purpose was to determine the role of major histocompatibility complex (MHC) genes in the genetic susceptibility to AP.

METHODS

Fifty-six Mexican Mestizo patients with AP underwent serologic typing for HLA class I and class II antigens. Class II MHC genes were also studied by DNA analysis. Findings in patients were compared with 100 ethnically matched healthy controls.

RESULTS

We found that 92.8% of patients with AP were HLA-DR4 positive (corrected p = 0.002; odds ratio [OR] = 10.1). The class I antigens HLA-A28 and HLA-B39 (B16) were also significantly increased (p < or = 0.000001, OR = 20.9 and p = 0.0001, OR = 6.7, respectively) compared with normal controls. Allele-specific oligonucleotide DR4 subtyping showed that 80.7% of HLA-DR4+ patients with AP were also positive for the DRB1*0407 allele.

CONCLUSION

These results confirm the role of HLA-DR4 (DRB1*0407) in the genetic susceptibility to AP and raise the possibility of a role for class I MHC antigens HLA-A28 and B16 in Mexican patients.

Hereditary polymorphic light eruption of American Indians: occurrence in non-Indians with polymorphic light eruption

BACKGROUND

Hereditary polymorphic light eruption (HPLE) occurs unique ly in the American Indian and Inuit and exhibits autosomal dominant transmission. Because the cutaneous expression of HPLE resembles that of polymorphic light eruption (PLE) and because many non-Indians in the United States have American Indian heritage, some instances of PLE may actually be HPLE.

OBJECTIVE

Our purpose was to determine whether non-Indian patients with PLE have characteristics suggestive of HPLE.

METHODS

We surveyed in Nebraska 25 European-Caucasian and 36 African-American patients with PLE for American Indian heritage and photosensitive relatives. Nonphotosensitive subjects (52 Caucasians and 40 African Americans) were surveyed for American Indian heritage.

RESULTS

American Indian heritage occurred in 11 Caucasian patients (44%); of those, seven (64%) had photosensitive relatives. Likewise, 29 African Americans (81%) had American Indian heritage; 19 (66%) of those had photosensitive relatives. American Indian heritage occurred in 10 Caucasian control subjects (19%) and in 34 African-American control subjects (85%).

CONCLUSION

If American Indian heritage and a family history of photosensitivity are definitive for HPLE, seven (28%) of our Caucasian patients and 19 (53%) of our African-American patients have HPLE rather than PLE. We urge physicians who suspect PLE in non-Indians to ask about American Indian heritage and photosensitive relatives and to screen their present patients with PLE for such characteristics.

HLA-DR4 may determine expression of actinic prurigo in British patients

Human leukocyte antigen (HLA) associations have been reported in Amerindian patients with actinic prurigo. To determine if similar associations are present in the British Caucasoid population with actinic prurigo, 26 patients underwent serological typing for HLC Class I and II antigens. DNA analysis by both sequence-specific priming and group-specific amplification with single-stranded oligonucleotide probe hybridization was used to confirm the DR and DQ typing and to perform DR4 subtyping. All patients were DR4 positive, and 25 of 26 patients were DQ7 positive. DR4 subtyping revealed 12 of 20 patients tested to be DRB1*0407. A nonsignificant association was also found with HLA B55 that is in linkage disequilibrium with DRB1*0407. No HLA associations were found in 25 British Caucasoid patients with polymorphic light eruption. DRB1*0407 is rare in European Caucasoids without actinic prurigo, and HLA-DR4 may have an important role in determining expression of this disease.

Actinic prurigo: clinical features and prognosis

BACKGROUND

Actinic prurigo, an idiopathic familial photodermatosis, has been described in Amerindians in Manitoba, Canada, as well as in the United States, Mexico, and South America.

OBJECTIVE

Our purpose was to describe the clinical features and prognosis of actinic prurigo in Amerindians in Saskatchewan, Canada.

METHODS

Clinical examinations, questionnaires, phototesting, and laboratory tests were used.

RESULTS

We present a series of 93 Amerindian patients. The face is the most commonly involved area. A hereditary tendency, cheilitis, and pruritus are prominent features. One third of patients report some lesions, often minor, during the winter. The majority of patients phototested were sensitive to ultraviolet A light.

CONCLUSION

We find the age of onset of actinic prurigo to be the most important feature in determining the type of eruption and the prognosis for the patient. In general the younger ages of onset (up to 20 years of age) are associated with cheilitis and more acute eruptions and are more likely to improve over 5 years. Those who develop actinic prurigo as adults (21 years of age and older) tend to have a milder and more persistent dermatosis.

HLA typing in polymorphous light eruption

Human leukocyte antigen typing of 41 white patients with polymorphous light eruption (limited concept) showed no significant differences when compared with the typing of 51 white control subjects. We previously found that actinic prurigo, an idiopathic photodermatosis particularly associated with Amerindians, has a positive association with antigens A24 and Cw4 and a negative association with A3. We suggest, on the basis of both laboratory and clinical findings, that polymorphous light eruption (limited concept) and actinic prurigo are two different and distinct diseases.