Researchers find ectodermal dysplasia prevalence lower than previously thought

Key takeaways:

• The birth prevalence for all ectodermal dysplasia cases was 14.5 per 100,000 live births.
• This estimate is five times lower than frequently cited estimates in prior literature.

Ectodermal dysplasia, a condition associated with impaired quality of life, increased mortality and increased morbidity, may have a lower prevalence than previously reported, according to a study.

“Ectodermal dysplasias (EDs) are a heterogeneous group of genetic disorders affecting the ectodermally-derived tissues, typically involving the skin and appendages (eg, hair, teeth, nails and eccrine sweat glands),” Laura Krogh Herlin, MD, a PhD student at Aarhus University in Denmark, and colleagues wrote in JAMA Dermatology. “Cardinal features of EDs include hypohidrosis, hypotrichosis, nail dystrophy and hypodontia.”

Due to the limited amount of data surrounding the prevalence of ED and the characteristics of patients suffering from this condition, Herlin and colleagues conducted a nationwide cohort study in Denmark.

The researchers used individual-level registry data recorded across the Danish universal health care system to identify patients with ED from Jan. 1, 1995, to Aug. 25, 2021. A total of 396 patients (median age at diagnosis, 13 years; 62.1% female) were included in the study, of which 319 had confirmed ED diagnoses and the remaining 77 were likely cases.

Results showed that the estimated minimum birth prevalence for all EDs was 14.5 (95% CI, 12.2-16.7) cases per 100,000 live births — an estimate five times lower than the frequently cited 70 cases.

“This difference may be partly explained by the new and more stringent definition of EDs, which has reduced the total number of disease subtypes substantially,” the researchers explained.

Results also showed that the prevalence of X-linked hypohidrotic EDs was 2.8 (95% CI, 1.8-3.8) cases per 100,000 live births. A previous study found that the prevalence was almost double that at 4.2 cases; however, these cases were confirmed with the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10), code Q82.4 which the researchers found had limited validity (positive predictive value, 71.5%).

Overall, the combined positive predictive value for an ED-specific diagnosis was low at 67% (95% CI, 62.7%-71%).

“The low PPVs and incomplete identification of ED using the ICD-10 codes in our study emphasize the importance of ED diagnosis validation and accurate disease registration,” the authors concluded.