Ganos et al. 2019

Quick Summary

This short report described a mother and son from a family previously reported with a rare dystonia syndrome. Both had generalized dystonia, severe speech or voice impairment, slow horizontal eye movements, and seizures that included photic myoclonus. "Photic" means triggered by light.

The key new finding in this paper was genetic. The authors reanalyzed the family using newer exome methods and found a shared IRF2BPL variant in the affected mother and affected son. The unaffected brother did not carry the same candidate variant. This supported IRF2BPL as the cause of the family's condition.

The report is small, but it is important because it showed that IRF2BPL-related disease can be inherited in an autosomal dominant pattern. Earlier reports had mostly emphasized de novo variants, where the variant is new in the affected person.

Why This Paper Matters

Before this report, IRF2BPL was already linked to neurodevelopmental regression, seizures, abnormal movements, loss of speech, dystonia, and slow eye movements. Most published cases with parent testing had de novo variants.

This paper added a different inheritance pattern. The affected mother and son shared the same IRF2BPL variant, showing that the condition can pass from an affected parent to an affected child. That matters for genetic counseling because inherited IRF2BPL disease may have different family implications than an apparently new variant.

The paper also focused attention on a recognizable clinical combination: dystonia with anarthria or aphonia, slow horizontal saccades, and seizures, including photic myoclonus. In plain language, the authors argued that this cluster should make clinicians consider IRF2BPL.

What The Researchers Studied

This was a short case report and genetic reanalysis of a family that had been clinically described in an earlier publication. The 2019 paper did not present a large cohort. It focused on two affected family members: the female index patient and her affected son.

The authors used trio-based exome analysis of the affected mother, affected son, and unaffected brother. They filtered for variants shared by the affected family members and absent from the unaffected brother. They then confirmed the candidate IRF2BPL variant with Sanger sequencing.

The paper also summarized key clinical information from the earlier report, the current genetic analysis, Figure 1, and the video legend.

What Was Learned About Symptoms

The index patient, the affected mother, had leg-onset generalized dystonia. The paper states that symptom onset varied in the family, with onset at 23 years for the index patient and early childhood for her son.

The index patient had severe anarthria or aphonia, meaning she had severe loss of speech or voice. She also had profound saccadic slowing, especially in the horizontal direction. In the video description, she had generalized dystonia including jaw-opening dystonia, photic myoclonus, and later spontaneous myoclonic jerks during examination.

Her brain MRI showed mild supratentorial and cerebellar brain atrophy. Neurophysiology showed axonal and demyelinating neuropathy affecting the peroneal and sural nerves. The video legend also notes gingival enlargement or hyperplasia and distal leg muscle atrophy, without evidence of spasticity. No cerebellar ataxia was seen on finger-to-nose testing in the video.

The affected son had generalized dystonia, including jaw-opening dystonia, aphonia, and markedly slowed horizontal saccades. The video legend reports no cerebellar ataxia. The paper also notes keratoconus in the male patient and lack of treatment response to pallidal deep brain stimulation.

Both affected family members were described as having epilepsy, including photic myoclonus. The report did not provide a full seizure diary or long-term treatment table.

What Was Learned About Genetics

The authors identified a heterozygous IRF2BPL nonsense variant: `c.355C>T`, `p.Gln119Ter`. The source paper writes the protein change as `p.Gln119*`.

A nonsense variant creates an early stop signal. In this family, the variant is near the beginning of the IRF2BPL protein. That means the expected protein product would be much shorter than the normal full-length protein.

The inheritance pattern was autosomal dominant. The affected mother and affected son carried the variant, while the unaffected brother was used in the filtering strategy. This was different from many earlier IRF2BPL reports, where affected individuals had de novo variants.

The paper used the genetic result to connect the family's syndrome to the broader IRF2BPL disease spectrum.

Patient And Cohort Details

The primary cohort for this extraction contains two affected family members.

The first row is the index patient, an affected mother. She had adult-onset leg-predominant dystonia that generalized, severe speech or voice loss, slow horizontal saccades, epilepsy with photic myoclonus, MRI atrophy, neuropathy, and later spontaneous myoclonic jerks.

The second row is her affected son. He had early-childhood onset according to the paper's discussion of onset variability, generalized dystonia, jaw-opening dystonia, aphonia, slowed horizontal saccades, epilepsy with photic myoclonus, keratoconus, and no reported response to pallidal deep brain stimulation.

The unaffected brother was not counted as a primary affected patient. Earlier literature cases mentioned for background were also not counted as primary rows.

What Families Can Take Away

This paper shows that IRF2BPL-related disease can sometimes run in a family. That does not mean every IRF2BPL case is inherited; many are de novo. It does mean that family history and parental testing can be important when doctors interpret an IRF2BPL result.

The symptoms in this family were centered on movement and speech: generalized dystonia, jaw-opening dystonia, severe speech or voice loss, slow horizontal eye movements, and light-sensitive seizure activity. This presentation may look different from early infantile epileptic encephalopathy or early childhood developmental regression.

The report also shows that the same gene can be linked to a broad range of neurological presentations. A family's specific variant, symptoms, inheritance pattern, and clinical course all matter.

Limits Of The Paper

This was a very short report. It described two affected family members and relied partly on the earlier clinical description and video material.

The paper did not provide a detailed table of all symptoms, seizure types, treatments, developmental milestones, or long-term outcomes. Some fields in the extracted cohort therefore remain blank when the 2019 paper did not explicitly report them.

The treatment information is limited. The paper mentions lack of response to pallidal deep brain stimulation in the male patient, but it does not establish a general treatment rule for IRF2BPL-related dystonia.

The report is still useful because the genetic result was clear and the clinical syndrome was distinctive, but it cannot define the full range of inherited IRF2BPL disease by itself.

Source Notes

* Author-accepted PDF: full short report, Figure 1 legend, and video legend. * PubMed record: PMID 31621620 and DOI 10.1016/j.parkreldis.2019.09.020. * Main text: family phenotype, genetic reanalysis, inheritance discussion, and diagnostic interpretation. * Figure 1: pedigree, index-patient MRI, and sequencing confirmation. * Video legend: index patient at ages 56 and 61 and affected son at age 27.