A homozygous truncating NALCN variant in two Afro-Caribbean siblings with hypotonia and dolichocephaly

Omotayo Ope, Elizabeth J. Bhoj, Beverly Nelson, Dong Li, Hakon Hakonarson, Andrew K. Sobering

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


NALCN encodes a sodium ion leak channel expressed in the nervous system that conducts a persistent influx of sodium ions to facilitate action potential formation. Homozygous or compound heterozygous loss of function variants in NALCN cause infantile hypotonia with psychomotor retardation and characteristic facies-1 (IHPRF1; OMIM 615419). Through exome and Sanger sequencing, we found two siblings of Afro-Caribbean ancestry who are homozygous for a known NALCN pathogenic variant, p.Arg735Ter, leading to failure to thrive, severe hypotonia, and dolichocephaly. The older sibling died suddenly without a known etiology after evaluation but before molecular diagnosis. An international collaboration originating from a resource limited Caribbean island facilitated molecular diagnosis. Due to its small population, geographical isolation, and low socioeconomic status, the island lacks many specialty medical services, including clinical genetics. Descriptions of genetic disorders affecting individuals of Afro-Caribbean ancestry are rarely reported in the medical literature. Diagnosis of IHPRF1 is important, as individuals with biallelic pathogenic NALCN variants are severely affected and potentially are at risk for cardiorespiratory arrest. Additionally, knowing the pathogenic variants allows the possibility of prenatal or preimplantation genetic diagnosis.

Original languageEnglish (US)
Pages (from-to)1877-1880
Number of pages4
JournalAmerican Journal of Medical Genetics, Part A
Issue number8
StatePublished - Aug 1 2020
Externally publishedYes


  • Caribbean
  • IHPRF1
  • dolichocephaly
  • hypotonia
  • sodium channel

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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