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Compound heterozygous ADAMTS9 variants in Joubert syndrome-related disorders without renal manifestation

Hiroko Baber Matsushita1, Takuya Hiraide2, Katsumi Hayakawa3

  • 1Department of Pediatrics, Kyoto Kuramaguchi Medical Center, Kyoto, Japan; Department of Pediatrics, Kyoto City Hospital, Kyoto, Japan.

Brain & Development
|November 9, 2021
PubMed

Insights

Defects in primary cilia cause ciliopathies, leading to developmental disorders. This study links ADAMTS9 gene variants to Joubert syndrome-related disorders, expanding the known phenotype.

Area of Science:

  • Genetics
  • Developmental Biology
  • Medical Science

Background:

  • Ciliopathies arise from primary cilia defects, causing diverse multisystem developmental disorders.
  • Joubert syndrome (JS) and JS-related disorders (JSRD) are examples of ciliopathies with varied organ involvement.
  • ADAMTS9 gene variants have previously been linked to nephronophthisis-related ciliopathies.

Observation:

  • A 4-year-old boy presented with compound heterozygous variants in the ADAMTS9 gene.
  • His clinical features included oculomotor apraxia, hypotonia, developmental delay, bifid tongue, and mild cerebellar vermis hypoplasia.
  • Notably, this case lacked the nephronophthisis and renal dysfunction seen in prior ADAMTS9 variant studies.

Findings:

  • The patient's presentation was indicative of Joubert syndrome-related disorders (JSRD).
  • This suggests a potential association between ADAMTS9 gene variants and the clinical spectrum of JSRD.
  • The findings highlight a broader phenotypic range for ADAMTS9-related ciliopathies than previously recognized.

Implications:

  • This case expands the understanding of the genetic basis and clinical variability of ciliopathies.
  • It emphasizes the importance of considering ADAMTS9 in the genetic diagnosis of JSRD, even without renal involvement.
  • Further research is warranted to fully elucidate the genotype-phenotype correlations of ADAMTS9 in ciliopathies.
Abstract

Keywords:
ADAMTS9 variantsCiliopathiesJoubert syndromeJoubert syndrome-related disordersNephronophthisis

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