Deciphering the modifiers for phenotypic variability of X-linked adrenoleukodystrophy

Figure 1 Possible modifiers associated with disease phenotypic variability. Phenotypic heterozygosity observed in a monogenic disorder can be due to the association of modifying factors such as genetic, epigenetic, and/or environmental factors, commonly termed as “modifiers.”

Figure 2 Factors determining the onset of symptoms of cerebral demyelination. Migration of immune cells into the brain could be a rate-limiting step in the appearance of symptoms of cerebral demyelination. Onset of the migration across the blood brain barrier could be precipitated by environmental triggers, genetic or epigenetic factors and ATP Binding Cassette Subfamily D Member 1 (ABCD1) deficiency acting either alone or in concert, marking the onset of brain inflammation leading to cerebral symptoms.