A Novel Variant in ABCD1 Gene Presenting as Adolescent-Onset Atypical Adrenomyeloneuropathy With Spastic Ataxia

Cerebello-brainstem dominant form of X-linked adrenoleukodystrophy with intrafamilial phenotypic variability

Objectives

This study aimed to describe the clinical and radiological characteristics of a cerebello-brainstem dominant form of X-linked adrenoleukodystrophy (X-ALD).

Methods

Three affected members from a family with cerebellar ataxia received full neurological, laboratory and radiological examinations. Genetic diagnoses were confirmed using whole-exome sequencing and protein structural modeling.

Results

All affected members presented with slurred speech, ataxia, and spasticity, but showed obvious differences in phenotypic severity and radiological findings. The levels of very long-chain fatty acids (VLCFA) were elevated in each member, while only one had adrenal dysfunction. Genetic analysis identified a hemizygous missense mutation (c.887A>G, p.Tyr296Cys) of the ATP-binding cassette subfamily D member 1 gene (ABCD1) in all affected members, which is likely to destabilize the overall structure of the ABCD1 protein.

Conclusions

We report a cerebello-dominant form of X-ALD caused by a missense variant in ABCD1. This report highlights intrafamilial phenotypic variability in X-ALD.

A novel ABCD1 G1202A mutation in a Chinese patient with pure adrenomyeloneuropathy and literature review

Adrenomyeloneuropathy (AMN) is a kind of varied disease caused by ABCD1 gene mutation and characterized by very-long-chain fatty acids (VLCFA) accumulation. It is diagnosed by clinical features, high VLCFAs levels and ABCD1 gene mutation. AMN is rarely reported in Chinese population. In this study, we report the genetic and clinical features of a Chinese pure AMN patient. Meanwhile, we conducted a literature review of AMN cases to summarize the characteristics of AMN. We report a rare Chinese pure AMN case with slowly progressive weakness of the lower extremities, caused by a novel c.1202G > A mutation in ABCD1 gene. The literature review indicates that spastic paraplegia is the mainly clinical manifestation in patients with AMN. VLCFAs and ABCD1 gene test should be performed in patients with spastic paraplegia of the lower limbs to diagnose AMN.