Background
The role of biallelic variants in the
NRCAM
gene underlying a neurodevelopmental disorder has been defined recently. The phenotype is mainly recognized by varying severity of global developmental delay/intellectual disability, hypotonia, spasticity, and peripheral neuropathy.
Methods
Here, we describe a patient with an initial diagnosis of motor‐predominant axonal polyneuropathy or a form of distal SMA. Whole‐exome sequencing (WES), in parallel with WES‐based CNV detection and assessment of homozygosity runs, was performed to identify this patient's possible genetic cause.
Results
Whole exome sequencing revealed a homozygous variant, c.73C > T (p.Gln25*), in the
NRCAM
gene, while the patient manifests a mild range of phenotypes compared to
NRCAM
‐related disorder. He presented only motor‐predominant axonal polyneuropathy with no other signs of central nervous system involvement.
Conclusions
This study is the second report of an association between biallelic
NRCAM
gene variants and a Mendelian disorder. The obtained clinical data, together with the molecular findings in this patient, expands the clinical and molecular spectrum of
NRCAM
‐related disorder and highlights its phenotypic complexity. Although patients with loss of function variants in this gene have previously presented severe clinical features, we show that type of the pathogenic variant does not necessarily determine the severity of this phenotype.