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Keywords:

  • ectodermal dysplasia;
  • classification;
  • functioning;
  • ICF-CY;
  • health;
  • disability

Abstract

  1. Top of page
  2. Abstract
  3. Current Classification of ED
  4. Classifications of Functioning
  5. THE ICF-CY AND CLASSIFICATION OF ED
  6. ICF-CY AS A COMPLEMENTARY CLASSIFICATION
  7. MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS
  8. CREATION OF A CONSENSUS TAXONOMY OF ED
  9. Acknowledgements
  10. REFERENCES

Ectodermal dysplasias (ED) encompass more than 200 conditions involving some combination of disorders of hair, nails, teeth, and sweat glands. The incidence of ED is relatively rare affecting about 7 of 10,000 births [Itin and Fistarol (2004)]. Individuals manifesting ED present with a wide range of disorders involving hair, nails, teeth, and sweat glands and in many cases other characteristics as well. The complex nature of the disorder has presented challenges for clinical practice and required the involvement of multiple approaches and disciplines. It has also resulted in significant research initiatives on cause and symptomatology. A significant challenge has been the search for comprehensive documentation of the varied and complex manifestations associated with ED. Existing classification systems of ED have focused on physiological and structural dimensions. Classification approaches with a broader focus including characteristics of functioning in persons with ED could facilitate clinical work and research initiatives. In this context, the potential utility of available classifications that address functioning and disability would be appropriate to consider in the search for a consensus classification of ED. To that end, the purpose of this article is to (a) review the status of classification of ED, (b) provide a brief overview of the International Classification of Functioning, Disability and Health-Children and Youth, ICF-CY [World Health Organization (2007); International Classification of Functioning, Disability and Health-Children and Youth. Geneva: WHO.], and (c) identify possible contributions of the ICF-CY to classification of ED's. © 2009 Wiley-Liss, Inc.


Current Classification of ED

  1. Top of page
  2. Abstract
  3. Current Classification of ED
  4. Classifications of Functioning
  5. THE ICF-CY AND CLASSIFICATION OF ED
  6. ICF-CY AS A COMPLEMENTARY CLASSIFICATION
  7. MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS
  8. CREATION OF A CONSENSUS TAXONOMY OF ED
  9. Acknowledgements
  10. REFERENCES

The challenge to classify characteristics of ectodermal dysplasia (ED) beyond the diagnostic dimensions provided by the ICD-10 has emphasized the need for a comprehensive classification that is applicable across disciplines and health professions and that can facilitate international scientific exchange. In response to this challenge, several classification systems have been proposed to promote a common approach in practice and research. One of these was based on classification of manifestations of ED by Pinheiro and Freire-Maia 1994. This classification was based on descriptions of the major clinical signs and symptoms involving manifestations of skin, sweat glands, hair, nails, teeth, face, and eye abnormalities. The pattern of manifested abnormalities served as the basis for defining two groups, A and B. Individuals defined by Group A pattern were those whose defects involved two or more of the primary disorders of hair, nail, teeth, and sweat glands. Individuals defined by the Group B pattern were those manifesting only one of the major abnormalities in conjunction with another disorder of the ectoderm such as lips or ears.

A second classification proposed by Priolo and Lagana 2001 was based on variations due to genetic factors. Two subgroups were also derived in this classification differentiated by defects of gene regulation and interaction [Itin and Fistarol, 2004]. A third classification proposed by Lamartine 2003 was based on molecular and biochemical factors and yielded four subgroups. The four subgroups are defined by functional criteria and involve cell–cell communication and regulation, adhesion, transcription regulation and development. A fourth molecular-genetic classification was advanced by Priolo et al. 2000 in which established relationships between genes and defects were associated with ED. In this classification, nine separate groups were identified ranging from “pure” ED manifestations to conditions associated with deafness or ocular defects.

The above classifications have focused on documenting characteristics of ED on the basis of biochemical and molecular dimensions and physiological and structural variation. A review of the above four classifications indicates that documentation of ED disorders has focused on the gene, cell, or body structure, however, characteristics of functional limitations of individuals with ED have not been included in the current classifications. Underlying defects of ED expressed in variations of an individual's functioning and adaptation as well as in alterations of that individual's appearance are important to document. Thus abnormalities of hair, skin, teeth, nails, and sweat glands are expressed in corresponding functional limitations of grooming, self-care, physical activities, eating, and speaking. Further, they may also be expressed in social and psychological consequences associated with the person's altered body structures, facial appearance or impaired functioning. Given the multi-dimensional nature of physical characteristics associated with ED, a consensus classification should encompass not only molecular and physiological disorders, but also problems of personal functioning. Such a classification would be an important addition for diagnostic and treatment applications for individuals with ED. With the goal of developing a consensus classification of ED it would be useful to examine classifications that have focused on functional dimensions and possible contributions to such a classification.

Classifications of Functioning

  1. Top of page
  2. Abstract
  3. Current Classification of ED
  4. Classifications of Functioning
  5. THE ICF-CY AND CLASSIFICATION OF ED
  6. ICF-CY AS A COMPLEMENTARY CLASSIFICATION
  7. MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS
  8. CREATION OF A CONSENSUS TAXONOMY OF ED
  9. Acknowledgements
  10. REFERENCES

There are three classifications that have addressed dimensions of functioning and disability. The International Classification of Impairments, Disabilities and Handicaps—ICIDH [WHO, 1980] represented an initial classification system of the consequences of disease manifested in relationships of impaired body function or structure, reduced ability to perform and associated disadvantage in social roles. Although representing a significant shift toward classification of functioning, the fact that it was published as a research document and not adopted by the World Health Assembly as a formal classification limited its widespread adoption and use. The Quebec Classification [Fougeyrollas et al., 1998a] is a taxonomy that frames disability within an interactive model of risk factors, organ system, capacities, and the environment expressed in life habits. It provides a useful perspective on the role of the environment in documenting the consequences of impairments and chronic conditions [Fougeyrollas et al., 1998b]. Although its application is expanding beyond Canada, the lack of universal status as a WHO publication limits its consideration as a candidate classification for application to ED.

The International Classification of Functioning, Disability and Health-ICF [WHO, 2001] is a comprehensive classification of health and functioning and joins the ICD-10 as a member of the WHO family of international classifications. The ICF drew on the ICIDH in its development but presented an interactive model of disablement rather than the linear model of the ICIDH. The ICF is unique in that it is a classification of health and functioning conceptualized in terms of neutral codes under four dimensions of Body Functions, Body Structures, Activities and Participation and Environmental Factors (Fig. 1). Each of these domains is defined by codes at the 4th, 5th, and 6th character level and organized in chapters. The content of codes follows a hierarchical structure with codes defining a major characteristic of function, structure, activities, or participation with sub-codes providing additional detail. Since its publication, the ICF has been adopted in health and health-related settings with growing applications including the use of codes in health records, assessment measures, and patient care. Of particular significance has been its promise as a common language for medicine as well as allied health disciplines as evidenced by the preparation of a practice manual by the American Psychological Association [Reed et al., 2005]. At broader levels, recommendations have been made for the adoption of the ICF to guide the initiatives of U.S. Government Agencies [National Academy of Sciences, 2007].

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Figure 1. Diagram of components of the WHO International classification of functioning, disability, and health.

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Since disorders associated with ED are congenital in nature and manifested in childhood [Lynch, 1992], it is important that a resource for a consensus classification is inclusive of developmental characteristics of children defined by the first two decades of life [Simeonsson et al., 2003; Simeonsson, 2005]. The ICF for children and youth ICF-CY [WHO, 2007] was derived from the ICF with the nature and organization of domains and the hierarchical structure codes within chapters identical to that of the ICF. The ICF-CY expanded content and increased specificity of detail focusing on developmental aspects of body functions and structures, activities and participation displayed by infants, toddlers, children, and adolescents. In keeping with the taxonomical structure of the ICF, new codes were added to the ICF-CY, for example, Primary Dentition (s32000) to the domain of Body Structures and Indicating the Need for Eating (d5500) to the domain of Activities and Participation. Documentation of the child's functioning with a code such as Caring for Teeth (d5201) is defined by an initial letter of “d” to indicate the domain of activity and participation, “5” as the chapter for self-care, “20” designating the caring for body parts and “1” as caring for teeth. The expansion of content in the ICF-CY was designed to capture indicators with codes for structures or functions appearing earlier in development anticipating codes of functioning manifested later in the individual's life. For example, the code for Primary Dentition (s32000) as noted previously is a precursor of the later code for Secondary Dentition (s32001).

The ICF-CY provides a classification of disability when documentation is made of structural or functional problems at the body or person level with the application of a universal qualifier. The defining values for the universal qualifier are mild = 1, moderate = 2, severe = 3, or complete = 4 problem and are entered following a decimal point in the numerical code. Disability is an umbrella term that refers to Impairments of Body Functions or Structures, Activity Limitations and Participation Restrictions. To reference “nails” as a characteristic of ED, the code for the typical state of Functions of Nails would be b860 and for the Structure of Nails it would be s830. To document a nail disorder in ED, the codes illustrated previously would be noted as b860.3 and s830.2 to reflect severe and moderate problems of function and structure, respectively. Coding these nail structures and function disorders with the ICF-CY could provide a standard language for the Freire-Maia and Pinheiro classification of ED. Since such disorders of nails are likely to negatively impact the performance of tasks involving hands and fingers, problems in Fine Hand Use and Caring for Fingernails could be documented with codes d440.2 and d5203.3 to denote moderate and severe problems respectively. A central contribution of the domain of Activities and Participation for classification of ED is thus that it offers codes to document how disorders of hair, nails, skin, and sweat glands affect the persons functioning in everyday life and relationships with others.

As the underlying framework of the ICF-CY presents disability as a product of the person–environment interaction, the domain of Environmental Factors consists of codes to classify the nature and extent of environmental barriers experienced by an individual. In that the severity of defects associated with ED such as disorders of the skin, nails, and hair may be impacted by the environment, the ICF-CY includes means to classify those aspects of the environment that may impede or facilitate functioning. In this context, the universal qualifier can be applied to quantify the extent to which environmental factors such as temperature (e2550) or humidity (e2251) may constitute barriers to functioning for a child with sensitive skin disorder of ED. Alternatively, documentation can be made of the extent to which a prosthetic device (e1151) facilitates the child's Biting (b15011) or Chewing (b1502) using the positive values (+1,2,3,4) of the universal qualifier.

The universal scope of the ICF and the ICF-CY provides a standard for classifying dimensions of functioning and disability regardless of underlying cause. The potential contribution of the ICF as a tool for dermatologic rehabilitation has been described by Niederauer et al. 2005. The ICF and ICF-CY can be applied to classify variations of body structures, body functions, activity and participation of persons with the health condition of ED as well as defining environmental factors influencing their condition or indicated in their treatment and care. As developmental indicators characterize many codes in the ICF-CY, it is well suited to document the onset of disorders in infancy and early childhood as well as their manifestation with maturity [Lollar and Simeonsson, 2005], a feature of value in documentation of developmental markers of ED. In addition, the ICF-CY may also be of use to define overlapping physical characteristics of children presenting with ED and other syndromes [Bertola et al., 2000].

THE ICF-CY AND CLASSIFICATION OF ED

  1. Top of page
  2. Abstract
  3. Current Classification of ED
  4. Classifications of Functioning
  5. THE ICF-CY AND CLASSIFICATION OF ED
  6. ICF-CY AS A COMPLEMENTARY CLASSIFICATION
  7. MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS
  8. CREATION OF A CONSENSUS TAXONOMY OF ED
  9. Acknowledgements
  10. REFERENCES

Potential contributions of the ICF-CY to the development of a consensus classification of ED could take a number of forms depending on what defines the intended outcome for the consensus classification. Three possible consensus outcomes that could be identified in this case are the combined use of available taxonomies, the modification of existing classifications or the generation of a new and unique classification. Three corresponding approaches that may be considered with respect to applications of the ICF-CY are: (a) use of the ICF-CY as a complement to existing classification of ED; (b) modification and expansion of content of an existing classification; and (c) contribution to an entirely new classification. Applications of the ICF-CY under each of these approaches are summarized in Table I with details discussed in the sections below.

Table I. Summary of Proposals for Using the ICF-CY in Classification of Ectodermal Dysplasias
Approach to ED classificationApplication of ICF-CY
ICF-CY complements existing ED classificationsa. Adoption as clinical tool in patient care
 b. Adopt conceptual framework to integrate classification
 c. Develop ED “core sets”
Expansion/modification of existing classificationsa. Cross reference ICF-CY notation in classifications
 b. Insert selected ICF-CY codes in classifications
Creation of new classificationa. Develop multi-axial classification

ICF-CY AS A COMPLEMENTARY CLASSIFICATION

  1. Top of page
  2. Abstract
  3. Current Classification of ED
  4. Classifications of Functioning
  5. THE ICF-CY AND CLASSIFICATION OF ED
  6. ICF-CY AS A COMPLEMENTARY CLASSIFICATION
  7. MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS
  8. CREATION OF A CONSENSUS TAXONOMY OF ED
  9. Acknowledgements
  10. REFERENCES

There are several ways in which the ICF-CY could be used to complement existing classifications currently used with individuals with ED. Each of these applications would serve to expand documentation of ED in children and adults and could be applied separately or in combination. First, the ICF-CY could be adopted as a clinical tool for documentation of patient characteristics for diagnosis and for recording health status over time. In this application, the ICF-CY would be accepted as an official classification for documenting characteristics of ED, in much the same way that the ICD-10 and other classifications are used for medical records.

In a second application, the conceptual framework as illustrated earlier in Figure 1 could be applied to identify the nature, focus, and means of assessing ED. With reference to the components of the model shown Figure 1, diagnostic information from ICD-9 CM would relate to the health condition component, whereas documentation of characteristics defined in the taxonomies proposed by Pinheiro and Freire-Maia 1994 and Priolo and Lagano would relate to the domains of Body Functions and Body Structure. The characteristics defined under the classifications proposed by Lamartine 2003 and Priolo et al. 2000 on the other hand are at the molecular level, a level not represented in the ICF-CY model or taxonomy. A review of these current classifications of ED indicates that their coverage would not provide documentation of problems with activities, participation, and the environment experienced by persons with ED.

A third potential application of the ICF-CY related to classification of ED is the development of “core sets” to summarize characteristics of the disorder. A core set consists of a limited number of classification codes that represent key indicators of characteristics associated with a health condition. The development of core sets has been a substantial application in rehabilitation medicine in which a specified set of ICF codes have been identified to characterize selected medical conditions such as multiple sclerosis [Kesselring et al., 2008] and rheumatoid arthritis [Stucki and Cieza, 2004]. Although the number of codes to include in a core set depends on the specific health condition, the goal is to select a relatively limited number that can capture the characteristics most persons with ED, perhaps a range including 20–50 codes. If core sets were to be developed for the condition of ED, it would be important to focus on codes that would capture the characteristics of ED that change with development. Given that manifested characteristics of ED differ significantly with age, core sets should be developed that correspond to key age groups (e.g., 0–2, 3–11, 12–19, 20+ years). In addition to codes capturing major disorders of hair, nails, teeth, and sweat glands, there are other codes from the domains of Body Functions and Structures, such as facial [Dellavia et al., 2008] and otologic disorders [Shin and Hartnick, 2004] that could be included. Codes from the domain of Activities/Participation also need to be identified representing difficulties experienced by persons with ED related to quality of life [Mehta et al., 2007]. It is important that characteristics selected for coding are ones that can be reliably observed by others with primary knowledge of the person with ED such as caregivers, teachers, and health professionals. Although some codes would be unique for a particular age group, many codes would be common across some or all age groups. An illustration of a possible core sets is presented in Table II with selected codes reflecting characteristics of ED. In the process of selecting codes for age group core sets, it is important to identify those that are specific to an age group and for which evidence can be reliably obtained in the form of test results, laboratory values, observations, and clinical report. Such evidence is necessary for applying the universal qualifier to define the severity of the problem (e.g., mild, moderate, severe, complete). If the core set is developed in a checklist format, a profile of functional status across codes can be obtained, defining the nature and severity of ED. A potentially useful application of core set data, or codes within the core set, are as variables in longitudinal studies of growth and development in children and youth with ED [Dellavia et al., 2008].

Table II. ICF-CY Codes in the Development of a Core Set for Characteristics of ED
ICF-CY codeDescriptionInfantChildrenYouthAdult
B550Thermoregulatory functions××××
B810Protective functions of skin××××
B850Functions of hair××××
B860Functions of nails××××
S32000Primary dentition××  
S32001Secondary dentition  × 
S820Structure of skin glands××××
D5200Caring for skin  ××
D5201Caring for teeth ×× 
D570Looking after one's health  ××
Other     

MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS

  1. Top of page
  2. Abstract
  3. Current Classification of ED
  4. Classifications of Functioning
  5. THE ICF-CY AND CLASSIFICATION OF ED
  6. ICF-CY AS A COMPLEMENTARY CLASSIFICATION
  7. MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS
  8. CREATION OF A CONSENSUS TAXONOMY OF ED
  9. Acknowledgements
  10. REFERENCES

The direct application of content from the ICF-CY is another form of contribution to a consensus classification of ED. One approach in this regard would be to include notation that cross-references the ICF-CY relative to items in an existing classification such as entries in clinical manifestation groups proposed by Pinheiro and Freire-Maia 1994. An example of notation referencing ICF-CY codes for a Group A combination of impaired sweat gland function and hair abnormalities is presented in Table III.

Table III. ICF-CY Notation in a Consensus Classification
Impaired sweat gland function (cf. ICF-CY b550)
 Absence or reduction of sweating
 Hyperthermia under warm condition
Abnormalities in hair follicles (cf. ICF-CY s840)
 Sparse, curly and fair hair
 Alopecia because of hypotrichosis
 Eyebrows or eyelashes absent

A second approach in the direct application of ICF-CY content for a consensus classification of ED would be the modification or expansion of an existing classification by inserting ICF-CY codes into relevant sections of the classification. An illustration of the insertion of ICF-CY codes into a consensus classification is presented in Table IV drawing on the list of clinical manifestations described by Itin and Fistarol 2004. The selection of codes to insert in the consensus classification should prioritize characteristics of ED that are not adequately detailed or covered in existing classifications.

Table IV. Example: Insertion of ICF-CY Codes Into Classification of Clinical Manifestations of ED
ManifestationBody structures codesBody function codes
Skin alterationS810B810-849
Impaired sweat glandsS820B550
Abnormalities in hair folliclesS840B850
Nail changesS830B860
Dental changesS32000/s32001B5101/b5101
Facial changesS7101/s8100 
Eye abnormalitiesS210-230B210-229

As noted previously, the focus of existing classifications of ED has been at molecular, genetic, or structural levels. Coverage of dimensions of impaired functioning associated with ED has been lacking. Such information could be added to a consensus classification with the ICF-CY at the level of individual codes, chapters, or blocks within chapters. If this approach to use content from the ICF-CY is considered, such application would need to be negotiated with WHO, publisher of the classification. There are, however, precedents of using content from an official WHO classification in this way. The ICD-10, for example, has been used with the International Classification of Primary Care-ICPC [Hofmans-Okkes and Lamberts, 1996], in the classification of illness and disease.

CREATION OF A CONSENSUS TAXONOMY OF ED

  1. Top of page
  2. Abstract
  3. Current Classification of ED
  4. Classifications of Functioning
  5. THE ICF-CY AND CLASSIFICATION OF ED
  6. ICF-CY AS A COMPLEMENTARY CLASSIFICATION
  7. MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS
  8. CREATION OF A CONSENSUS TAXONOMY OF ED
  9. Acknowledgements
  10. REFERENCES

Two applications of the ICF-CY can be considered if the development of a new taxonomy is the goal of a consensus classification of ED. Both applications would be based on the derivation of a multi-axial classification but would differ in terms of how the ICF-CY is used. In one application, selected content of the ICF-CY serves as an axis in a composite taxonomy. In a second application, the conceptual framework of the ICF-CY is proposed as the basis for constructing a new multi-axial taxonomy. This proposal is similar to the recommendation made by Sharpe et al. 2006 for a conceptually based taxonomy with axes defined by symptoms and biological, psychological, and social factors.

The number of axes to be included in a multi-axial classification of ED would require systematic review and analysis of contents. For the purpose of this article five axes are proposed to illustrate the composite taxonomy as well as one based on the conceptual base of the ICF-CY (Table V). The five axes in the composite taxonomy could draw on several of the existing classifications of ED described previously as well as other classification such as the ICD-10 or International Classification of Primary Care. There are precedents for composite taxonomies, the ICD-10 Guide for Mental Retardation [WHO, 1996; Einfeld and Tonge, 1999] is an example of a composite taxonomy developed to document impairment and disability. Although its focus and content would differ from the content of ED, its structure could serve as a guide in the development of a composite taxonomy for ED.

Table V. Models of Multi-Axial Classifications of ED
CompositeConceptual
Axis I: Clinical manifestations [Pinheiro and Freire-Maia, 1994]Axis I: Genetic factors
Axis II: Clinical genetic [Priolo and Lagana, 2008]Axis II: Molecular structures and functions
Axis III: Molecular basis [Lamartine, 2003]Axis III: Body structures and functions (ICF-CY)
Axis IV: Body structures and functions (ICF-CY)Axis IV: Activities/participation (ICF-CY)
Axis V: Activities/participation (ICF-CY)Axis V: Environmental factors (ICF-CY)

The development of a conceptually based multi-axial classification of ED would require the adoption of a comprehensive model of human functioning. The comprehensive framework of health and functioning in the ICF-CY could serve that purpose with domains defining three of the axes. In that the ICF-CY does not classify elements below the level of body systems, additional axes would be needed to classify genetic and molecular levels respectively. As illustrated in Table V, the first two axes in the multi-axial classification encompass genetic and molecular aspects of ED, reflecting successive structural and functional levels for Axis I through IV based on the organizing framework of the ICF-CY. Environmental factors of importance to document for persons with ED could be codes on Axis V in two ways. First, documentation could be made of factors exacerbating ED such as temperature or humidity for a skin condition. Documentation could also be made of environmental factors involved in treatment and care of persons with ED, such as the use of assistive devices.

This review has advanced potential applications of the ICF-CY to a consensus classification of ED in order to improve treatment and care of individuals with ED. Whether applied in part or in its entirety, the ICF-CY offers a system for documentation of problems of human functioning, encompassing characteristics of ED not covered in current classifications of the condition. To that end, the conceptual framework and common language of the ICF-CY may facilitate multi-disciplinary work and advance clinical, administrative, and research documentation related to the condition of ED.

REFERENCES

  1. Top of page
  2. Abstract
  3. Current Classification of ED
  4. Classifications of Functioning
  5. THE ICF-CY AND CLASSIFICATION OF ED
  6. ICF-CY AS A COMPLEMENTARY CLASSIFICATION
  7. MODIFICATION OR EXPANSION OF EXISTING CLASSIFICATIONS
  8. CREATION OF A CONSENSUS TAXONOMY OF ED
  9. Acknowledgements
  10. REFERENCES