Summary¹

Heritable disorders of connective tissue (HDCTs) are a diverse group of many inherited (genetic) disorders and subtypes. Connective tissue is an integral component of all organ systems and plays a crucial role in their function. Hence, the physical and mental impairments associated with HDCTs manifest throughout the body and affect functioning in every body system. These impairments may develop and vary in severity (wax and wane) throughout an affected individual’s lifetime.

The natural history of HDCTs as a general group demonstrates several commonalities, including their multisystem nature and the impairments they may cause. Nevertheless, the clinical course of individuals with an HDCT is highly variable with respect not only to the disease-specific manifestations of each disorder but also to the ways in which the disorders manifest in each affected individual, as well as the effects of environmental factors and physical and psychological demands to which the person is exposed.

The severity of HDCTs cannot be measured by a single genetic or laboratory test. Rather, their severity is determined by the severity of the physical and mental manifestations experienced by affected individuals, which may be measurable with existing clinical and function testing. The impact of HDCTs on functioning results from the combined effects of the multiple impairments with which they are associated in different body systems, which may be severe collectively even if “less severe” individually. In some cases, the impairments experienced by individuals with an HDCT are

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¹ With the exception of direct quotations, this summary does not include references. Citations to support the text and conclusions herein are provided in the body of the report.

severe enough to qualify them for disability benefits from the U.S. Social Security Administration (SSA).

SSA provides financial assistance to people with disabilities through two programs: Social Security Disability Insurance (SSDI) (Title II of the Social Security Act) and Supplemental Security Income (SSI) (Title XVI of the Social Security Act). The SSDI program, established in 1956, provides benefits to eligible adults with disabilities who have paid into the Disability Insurance Trust Fund, as well as to certain family members. The SSI program, created in 1972, is a means-tested program based on income and financial resources that pays benefits to eligible adults and children with disabilities, individuals who are blind, and adults aged 65 and older.

In 2020, SSA requested that the Health and Medicine Division of the National Academies of Sciences, Engineering, and Medicine convene a committee of relevant experts to review current information and provide findings and conclusions regarding the diagnosis, treatment, and prognosis of selected HDCTs, including Marfan syndrome (MFS) and the Ehlers-Danlos syndromes (EDS), in adults and children. In the statement of task for the study, SSA also asked the committee to provide information on the relative levels of functional limitation typically associated with the disorders and their common treatments, and to identify any “non-exertional physical… and mental limitations (e.g., cognitive or behavioral) that are equivalent in severity to the standard represented in [SSA’s] listings (i.e., that would prevent any gainful activity) but are not captured by currently existing listings and are not currently reflected in SSA’s disability grid rules.”² The committee was tasked as well with providing a summary of selected treatments currently being studied in clinical trials.

STUDY APPROACH AND SCOPE

The committee conducted an extensive review of the literature pertaining to HDCTs and work-related functioning. In addition, this review included websites maintained by such organizations as the International Consortium on Ehlers-Danlos Syndromes & Hypermobility Spectrum Disorders, the EDS & HSD Community Coalition (formerly “the EDS Comorbidity Coalition”), The Ehlers-Danlos Society, The Marfan Foundation, and SSA. Committee members and project staff identified additional salient literature and information using traditional academic research methods and online searches throughout the course of the study. The committee also drew on

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² SSA’s grid rules reflect functional and vocational patterns and in certain cases, incorporate into disability determinations analysis of vocational factors (i.e., age, education, previous work experience) in combination with the individual’s residual functional capacity (https://www.ssa.gov/OP_Home/cfr20/404/404-app-p02.htm [accessed February 24, 2022]).

a variety of additional resources, including invited speakers with expertise in HDCT-associated gastrointestinal conditions, mental health conditions, and orthostatic intolerance (a condition in which individuals develop symptoms upon assuming and maintaining upright posture), as well as a panel discussion with patient advocates. The committee’s work was informed further by a commissioned paper on the functional impact of orthostatic intolerance in EDS.

Definition of Disability

The concept of disability has evolved over the past several decades from a medical to a biopsychosocial model. The latter model, exemplified by the World Health Organization’s International Classification of Functioning, Disability and Health (ICF), portrays disability as “the interaction between an individual (with a health condition) and that individual’s contextual factors (environmental and personal factors).”³ The ICF model recognizes functioning in three domains: (1) body function and structure, which encompass physiological functions of the body, including psychological functions, as well as the functioning of body structures (e.g., movement of limbs, cardiac function); (2) activities, which are actions or tasks (e.g., running, problem solving); and (3) participation, which is the performance of tasks in a societal context (e.g., participation in school or organized sports). The model refers to deficits in body function and structure as impairments, deficits in completing activities as limitations, and reductions in participation as restrictions. Accommodations, such as assistive technologies and environmental modifications, are environmental contextual factors that act on the ICF domains to enhance an individual’s activity and participation.

SSA employs different definitions of disability for adults and children. For adults, the definition is “inability to engage in any SGA [substantial gainful activity] by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months.”⁴ SGA is work activity that “involves doing significant and productive physical or mental duties” or activity that “is done (or intended) for pay or profit,” regardless of whether a profit is realized.⁵ In the SSA context, “disability” in adults refers to work disability—an inability to participate in work “in an ordinary work setting, on a regular and continuing basis,

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³ WHO (World Health Organization). 2001. International classification of functioning, disability and health. Geneva, Switzerland: WHO. https://apps.who.int/iris/handle/10665/ (accessed July 22, 2022).

⁴ 42 U.S.C. 423(d)(1); see also 20 CFR 404.1505; 20 CFR 416.905.

⁵ 20 CFR 404.1510; 20 CFR 404.1572.

and for 8 hours per day, 5 days per week, or an equivalent work schedule.”⁶ SSA incorporates assessment of function into its definition of disability for children (i.e., those less than 18 years of age). It considers children who are not engaged in SGA to be disabled if they have a “medically determinable physical or mental impairment or combination of impairments that causes marked and severe functional limitations, and that can be expected to cause death or that has lasted or can be expected to last for a continuous period of not less than 12 months.”⁷

In its consideration of functioning among individuals affected by HDCTs, this report focuses on those physical; vision, hearing, and speech; and mental activities the committee determined to be most relevant to SSA. The committee made this determination based on the information SSA collects about disability applicants and the information the U.S. Bureau of Labor Statistics collects about the physical and mental demands of jobs for inclusion in the Occupational Information System.

Selection of Heritable Disorders of Connective Tissue for This Study

The committee’s statement of task requests information about “selected [HDCTs], including but not necessarily limited to Ehlers-Danlos syndrome[s] and Marfan syndrome.” As directed in the statement of task, this report focuses primarily on MFS and EDS because of their relative prevalence. MFS is an autosomal-dominant disorder that affects multiple organ systems, especially the ocular, cardiovascular, and skeletal systems. Thirteen types of EDS have been identified, all of which share common elements of joint hypermobility and skin and soft tissue involvement; hypermobile EDS (hEDS) is by far the most prevalent EDS type. In addition to MFS and EDS, the committee identified for inclusion in the report several other hereditary aortopathies (Loeys-Dietz syndrome, congenital contracture arachnodactyly [also known as Beals-Hecht syndrome], and Shprintzen-Goldberg syndrome) and hypermobility spectrum disorders (HSD) because of the features they share with MFS and hEDS, respectively.

Terminology

Secondary Impairments

The committee was tasked with describing, to the extent possible, “secondary impairments” that result from the HDCTs or their treatments.

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⁶ SSA. 2021. DI 24510.057 sustainability and the residual functional capacity (RFC) assessment https://secure.ssa.gov/poms.nsf/lnx/0424510057 (accessed May 23, 2022).

⁷ 20 CFR 416.906; see also 42 U.S.C. 1382(c).

Because there is not always a known or clear causal link between the disorder and all of its manifestations, the committee understands “secondary impairments” to mean physical and mental manifestations (medical diagnoses, syndromes, or comorbid and other health conditions) that are either associated with or may result from an HDCT. Many of these are not specific to HDCTs and can also occur in other individuals. Use of this term thus defined does not mean that any of the physical or mental manifestations seen in individuals with HDCTs are not core elements of the disorders. Rather, the primary impairment is the underlying genetic disorder (e.g., EDS, MFS), while the secondary impairments encompass all of the physical and mental manifestations of that disorder. The committee considered the number, types, and severity of the secondary impairments experienced by individuals with an HDCT to be of particular importance with regard to the functional implications of these disorders.

Treatment and Management

The committee was tasked with addressing several issues related to the “types of treatments available” for HDCTs. For the purposes of this report, the committee distinguishes between “treatment” and “management”: whereas treatment focuses on curing or mitigating a specific disease (in this case an HDCT), management focuses on caring for the person as a whole, which requires a multidisciplinary team and extends throughout the life course. Although no curative treatments currently are available for MFS or EDS, these disorders can be managed. Management involves supportive care, early diagnosis of the multisystem manifestations, treatment of associated physical and mental secondary impairments, and strategies for reducing or preventing problems that may present over time.

Severity

The committee was tasked with identifying possible indicators of “the clinical or medical severity” of HDCTs, and was asked to indicate in this report when the terms “severity” and “severe” are being used as they would be in “clinical or medical care settings” versus in “SSA’s work-related program definition (i.e., an impairment of such severity as to be the basis of a finding of an inability to engage in any substantial gainful activity).” For the purposes of this report, the terms “severe” and “severity” are used as they typically would be in clinical or medical care settings. When the terms reflect SSA’s program definition, their usage is specified as such.

OVERALL CONCLUSIONS

The committee formulated eight overall conclusions in seven areas: (1) nature of heritable disorders of connective tissue, (2) heritable disorders of connective tissue and disability, (3) diagnosis, (4) management, (5) barriers to access to care, (6) education, and (7) research gaps. In addition, at the end of several chapters, the report contains findings and conclusions specific to the evidence presented in those chapters.

Nature of Heritable Disorders of Connective Tissue

As described above, HDCTs affect connective tissues, which are present in and affect the functioning of all organ systems throughout the body. For this reason, HDCTs manifest in secondary impairments throughout the body that may develop and fluctuate in severity over time, and can have widespread and varied effects on physical and mental functioning. The severity of HDCTs relates to the severity of the physical and mental secondary impairments experienced by affected individuals, including the combined effects of multiple impairments, as well as the frequency, severity, and predictability of their fluctuations. Secondary impairments in any of the body systems can be severe and adversely affect an individual’s functioning; limitations associated with pain, fatigue, and anxiety may be particularly pronounced. The functional limitations experienced by individuals with HDCTs are also affected by environmental factors (e.g., extreme heat and cold, noise and vibration, smells, wetness and humidity, other atmospheric conditions, irritants). In addition, physical and mental demands related to school or work may precipitate or exacerbate these limitations.

For these reasons, the committee drew the following overall conclusion:

1. Heritable disorders of connective tissue (HDCTs) comprise a large and varied group of disorders in children and adults that share the common feature of pronounced involvement of connective tissues, usually in multiple organ systems. HDCTs can lead to a variety of physical and mental secondary impairments (i.e., manifestations, medical diagnoses, syndromes, comorbidities, or other health conditions) and associated functional limitations. Impairments can range from minor to severe and even life-threatening and may fluctuate in severity over time in an individual. Functional limitations may be sufficiently severe to interfere with participation in work and school, as well as social and recreational activities, and may include precautions and restrictions on activities to avoid aggravating the condition.

Heritable Disorders of Connective Tissue and Disability

A challenge in assessment of functioning in individuals with HDCTs is capturing the full effect of their impairment(s) on their daily activities, including participation in work and school. This is particularly true when a person has multiple impairments. Individuals with HDCTs may experience significant variability in their physical and/or mental secondary impairments from day to day or even within a single day. This variability is often unpredictable and may limit the ability to sustain gainful employment.

The committee reviewed SSA’s Listing of Impairments-Adult Listings and found that some of the listings include severity criteria for some of the secondary impairments that may be experienced by individuals with MFS, EDS, and other HDCTs. The committee also concluded that other listings, with some modification, could apply to certain secondary impairments experienced by individuals with HDCTs. The committee found further that the combined effects of an individual’s secondary impairments may limit function with a degree of severity sufficient to preclude the individual’s participation in work on a “regular and continuing basis” (i.e., 8 hours per day, 5 days per week, or an equivalent work schedule) or, for children, to cause “marked and severe functional limitations.” The concept of functional equivalence used by SSA in some disability determinations in children is particularly well suited to evaluating the combined effects on an applicant’s functioning of the many and varied impairments that often manifest in HDCTs and other multisystem disorders.

For these reasons, the committee drew the following overall conclusion:

2. Some of SSA’s Adult Listings apply directly to secondary impairments experienced by individuals with HDCTs and could be used to evaluate disability in those individuals. Other listings, with some modification, could apply to certain secondary impairments experienced by individuals with HDCTs.

Diagnosis

Early diagnosis of HDCTs is important to reduce physical injury, reduce psychological harm to the affected individual and family members, and prevent the risks associated with inappropriate or fragmented medical care. HDCTs are diagnosed through a combination of clinical findings and established clinical criteria, followed by confirmatory molecular genetic testing when specific genes have been identified for the suspected disorder. Some HDCTs, such as hEDS, do not yet have a known genetic marker or test, and the absence of molecular genetic testing should not necessarily rule out the diagnosis if the clinical suspicion remains based on clinical findings.

An HDCT diagnosis should be considered for individuals who present with previously undiagnosed complex multisystem disorders; however, diagnosis of some HDCTs, in particular EDS, is often delayed, in some cases for a decade or more. One reason for delayed diagnosis is that because HDCTs can cause a wide variety of physical and mental secondary impairments involving multiple organ systems, patients often are referred to a succession of different specialists. Other factors may contribute to delayed diagnosis, including minimal training in and knowledge about the disorders among health care providers and a corresponding shortage of clinicians with expertise in diagnosing and managing them. Delayed diagnosis may exacerbate manifestations of HDCTs or have life-threatening consequences.

For these reasons, the committee drew the following overall conclusion:

3. Early diagnosis of HDCTs is important to reduce physical injury, reduce psychological harm to the individual and family members, and prevent the risks associated with inappropriate or fragmented medical care.
   • Diagnosis of HDCTs is often delayed because of
     • the multisystem, complex, and phenotypically variable nature of the disorders;
     • lack of knowledge about HDCTs among health care providers, patients and family members, and other stakeholders;
     • lack of experience with using the syndromic approach to diagnosis, in which diagnosis is based on characteristic groups of symptoms and signs;
     • lack of access to comprehensive, multidisciplinary care teams with expertise in HDCTs (due to a shortage of clinicians, especially in some geographic areas);
     • historical bias and denial among health care providers, patients, and family members about the reality of the lived experience of manifestations of the disorders; and
     • inaccurate expectations that there will be a diagnostic genetic test for every HDCT.
   • Delayed or misdiagnosis of individuals with HDCTs can result in
     • inappropriate medical interventions;
     • inability to accurately assess the risks and benefits associated with medical procedures;
     • inability to access necessary reasonable accommodations at work or school;
     • family stress and dysfunction;
     • stress associated with unexplained and repeated evidence of trauma, leading to inappropriate suspicion of child abuse;
     • inappropriate assessments and incorrect diagnoses; and

• • mistrust of health care providers and negative expectations for future health care encounters.
• Timely diagnosis and recognition of the many physical and mental secondary impairments with which HDCTs can present and action to address them, even if in the absence of a specific molecular diagnosis, can dramatically improve individuals’ quality of life and functional status, including the ability to participate in work and school.

Management

As noted, there are currently no curative treatments for HDCTs, but appropriate management can reduce the frequency and severity of the disorders’ manifestations and resulting functional limitations. Management of the HDCTs involves supportive care, early diagnosis and treatment of associated physical and mental secondary impairments, and preventive strategies to lessen or prevent problems that may occur over time. Because of the complex, multisystem nature of HDCTs, high-quality care for individuals with these disorders relies on effective coordination among a team of health care providers across a broad range of disciplines with expertise in the disorders.

For these reasons, the committee drew the following overall conclusion:

4. Although curative treatments for HDCTs do not exist at this time, appropriate understanding and management of the disorders can reduce the frequency and severity of their manifestations and resulting functional consequences. High-quality care for individuals with HDCTs relies on effective coordination among a team of clinicians across a broad range of physical and mental health care disciplines who are knowledgeable about these disorders.

Barriers to Access to Care

Given the general lack of knowledge about HDCTs among clinicians, individuals with these disorders often have difficulty obtaining appropriate and integrated multidisciplinary care to address the wide range of associated impairments. Insufficient training in and knowledge about the disorders among health care providers contribute to a shortage of clinicians with expertise in diagnosing and managing them. In addition, access to multidisciplinary teams and relevant specialists is limited or nonexistent in rural areas; even many university centers lack multidisciplinary teams with expertise in HDCTs.

For these reasons, the committee drew the following overall conclusion:

5. Access to comprehensive, multidisciplinary care for the diagnosis and management of HDCTs can be limited by geography and other factors, including the availability of care teams with expertise in the disorders.

Education

Education about HDCTs, including their multisystem manifestations, diagnosis, and management, is important for all health care providers to help increase recognition and earlier diagnosis of the disorders. With appropriate education, a variety of health care providers, including, for example, physicians, nurses, psychologists, neuropsychologists, rehabilitation specialists (e.g., physiatrists; physical, occupational, and speech therapists), nutritionists, and others, should be able to recognize HDCTs and direct affected individuals to the appropriate care providers for management. Clinicians performing procedures or providing anesthesia and periprocedures management need to be aware of the altered procedural and postprocedural risks associated with HDCTs and to have a screening strategy for these disorders. It is also important for individuals with HDCTs and their family members to learn about strategies for preventing or mitigating symptoms, as well as the risks associated with certain activities that may result in physical trauma, such as physically demanding activities or pregnancy and childbirth. Relevant support groups provide valuable education regarding the manifestations and lived experience of the disorders.

For these reasons, the committee drew the following overall conclusions:

6. Education about HDCTs, including their multisystem manifestations, diagnosis, and management, is important for all clinicians to help increase recognition and earlier diagnosis of the disorders and enable the provision of appropriate care.
   • A variety of health care providers should be able to recognize HDCTs and direct affected individuals to the appropriate clinicians for management.
   • Individuals with HDCTs and relevant support groups can provide valuable insight regarding the manifestations and lived experience of the disorders.
   • Increased recognition of the breadth and scope of HDCTs by health care professional education programs, professional organizations, and publishers of quality biomedical research is needed.

7. Education of individuals with the disorders and their families, as well as employers and school staff, is important to improve the quality of life for affected individuals and their families, to facilitate appropriate accommodations at work and school, and to help inform the disability assessment and determination process.

Research Gaps

HDCTs can be difficult to diagnose, and the true prevalence of many of these disorders is unknown. As noted above, HDCTs are diagnosed through a combination of clinical findings and established clinical criteria, followed by confirmatory molecular genetic testing when specific genes have been identified for the suspected disorder. However, diagnosis of hEDS and HSD is based solely on clinical criteria, since currently no associated causative genes have been identified for either disorder. Understanding of and diagnostic criteria for these disorders continue to evolve.

There currently are no curative treatments for MFS and related hereditary aortopathies, EDS, or HSD, making this an important area for research. In addition, more research is needed to improve recognition, management, and outcomes of the many secondary impairments associated with these disorders.

The clinical course of HDCTs and their effects on functioning vary greatly among affected individuals. Longitudinal studies of individuals with different HDCTs would increase understanding of the clinical course of the disorders; associated functional limitations; and potentially the impact of interventions, including reasonable accommodations, on participation in work and school.

While the severity of HDCTs is linked to the severity of the affected individual’s physical and mental secondary impairments, including the combined effects of multiple impairments, improved understanding and measurement of the effects of impairments and multiple impairments on functioning could advance management of the disorders and improve functional status and quality of life for patients.

For these reasons, the committee drew the following overall conclusion:

8. Ongoing research on HDCTs is important to advance understanding of the disorders and their effects. In particular, research on care services and interventions for HDCTs and secondary impairments is needed, including
   • more specific diagnostic criteria and biomarkers;
   • functional and biomeasures of severity;

1. • effective treatment for HDCTs and management of their physical and mental manifestations, including comparative treatment trials;
   • the clinical course of the disorders throughout the lifetime of affected individuals;
   • the impact of relevant reasonable accommodations on affected individuals’ ability to participate in work and school; and
   • benefits versus risks of participation in common childhood activities (e.g., contact sports, gymnastics, dance).