EDA Deletion/Duplication (MLPA) Analysis Test Details
X-Linked Hypohidrotic Ectodermal Dysplasia (XLHED) is characterized by three cardinal features: hypotrichosis (sparse hair), hypohidrosis (reduced sweating) and hypodontia (absence of teeth) (Wright 2009). Individuals with XLHED often have hair that is thin, slow-growing, and lightly pigmented. Eyebrows may also be sparse or missing. Individuals will also have absent or reduced sweating, which can lead to hypothermic episodes if body temperature is not controlled externally. Teeth can also be affected and are either missing entirely or formed abnormally with delayed eruption timing. The teeth are typically smaller than average with conical crowns. Female carriers can show abnormal patterns of sweat pore distribution and function. Additionally, some degree of hypodontia and mild hypotrichosis can be seen in female carriers (Cambiaghi 2000). Affected individuals may have other features including fragile appearing skin, raspy voice, decreased sebaceous secretions, and abnormal nasal secretions. Typical facial features have been noted in some individuals with XLHED such as frontal bossing, protruding lips, saddle nose and sunken cheeks.Read More...
X-linked hypohidrotic ectodermal dysplasia is inherited in an X-linked manner and caused by variants in the EDA gene. Over 100 variants (including missense, nonsense and splicing) have been identified in individuals with XLHED, but no clear genotype-phenotype correlations have been noted. However, some individuals with isolated dental phenotypes have also been found to have missense variants in EDA (Mikkola 2008).Less
The MLPA test for deletions or duplication of EDA gene is recommended for males with clinical features of XLHED or females with milder features and/or family history. Pathogenic variants in the EDA gene account for 95% of all cases of XLHED. Sequencing variants are more common type of variant identified, so reflexive testing from DNA sequencing to deletion/duplication analysis (See EDA Gene Sequencing Test page) can be performed. An overlapping phenotype is seen with the autosomal dominant and recessive forms of hypohidrotic ectodermal dysplasia; however, the X-linked form is most common accounting for up to 60% of HED. This should be taken into consideration during a medical evaluation and family history assessment.
This test is performed by multiplex ligation-dependent probe amplification (MLPA) to detect the presence or absence of a deletion or duplication of one or more exons spanning the listed genes.
Analytical and Clinical Sensitivity
This test is greater than 98% accurate in detecting single or multiple exon deletions and/or duplications at the analyzed loci. Approximately 95% of males with a clinical diagnosis of X-Linked Hypohidrotic Ectodermal Dysplasia have pathogenic variants in the EDA gene. Up to 12% of those individual could have deletions spanning one of multiple exons of the EDA gene (LMM unpublished data).