On this page, you will find information about a genetic change that was identified in a UDN participant. We are trying to find others with the same or similar condition.

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A change in the HLCS gene was identified in a UDN participant with decline in language and memory (cognitive regression), sudden muscle jerks (myoclonus), and increased muscle tone in lower limbs (limb hypertonia)

Date of Report

Mar 20, 2023

Full Name

holocarboxylase synthetase

Chromosome 21 (21q22.13)


The HLCS gene links biotin to propionyl-CoA carboxylase, pyruvate carboxylase, alpha-methylcrotonyl-CoA carboxylase and acetyl-CoA carboxylase (Suzuki et al., 1994).

Database Links

GeneCards: HLCS

MedlinePlus Genetics: HLCS

NCBI Gene: 3141

OMIM: 609018

UniProtKB/Swiss-Prot: P50747

Clinical Significance

A heterozygous change in this gene was identified in a UDN participant. Research is underway to see if this change is causing symptoms in this participant.

Inheritance Pattern Autosomal recessive
Position (hg19) chr21:g.38139542G>A
Transcript NM_000411.8
DNA Change c.1496C>T
Protein Change p.Ala499Val
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