Baratela-Scott syndrome (XYLT1)
| Dred_ID | RD00029 |
| OMIM ID | 615777 |
| Disease name | Baratela-Scott syndrome |
| Alternative names | BSS |
| Category | Genetic diseases, Neuronal diseases |
| Phenotype | In 2012 Baratela-Scott syndrome was identified in humans. A GGC repeat expansion, and methylation of exon 1 of XYLT1 is a common pathogenic variant in Baratela-Scott syndrome. Patients with Bartarlla-Scott syndrome exhibit abnormal development of the skeleton, characteristic facial features, and cognitive developmental delay. Skeletal problems include knee cap in the wrong position, short long bones with mild changes to the narrow portion, short palm bones with stub thumbs, short thigh necks, shallow hip sockets, and malformations of the spine. Characteristic facial features include a flattened midface with a broad nasal bridge, cleft palate, and unibrow. The syndrome also cause pre-school onset of a cognitive developmental delay, with a shortened attention span. Some of the cognitive delay is masked by a warm and engaging personality. |
| Miscellaneouse | N/A |
| Prevalence | N/A [source: MalaCards] |
| Inheritance | autosomal recessive |
| Anticipation | Yes |
| Evidence | Strong |
| Gene symbol | XYLT1 |
| Alias symbols | XT1; XTI; XT-I; DBQD2; XYLTI; PXYLT1; xylT-I |
| Gene name | xylosyltransferase 1 |
| Gene map locus | 16p12.3; chr16:17,101,769-17,470,960(-) |
| Ensembl Gene ID | ENSG00000103489 |
| Gene expression and Gene Ontology | BioGPS |
| Protein expression | Human Protein Atlas |
| Gene sequence | Sequence |
| Variation | ClinVar, dbSNP | Gene conservation | Gene Conservation from UCSC Genome Browser |
| Gene Description | This locus encodes a xylosyltransferase enzyme. The encoded protein catalyzes transfer of UDP-xylose to serine residues of an acceptor protein substrate. This transfer reaction is necessary for biosynthesis of glycosaminoglycan chains. Mutations in this gene have been associated with increased severity of pseudoxanthoma elasticum. |
| Repeat unit | GGC |
| Normal repeat copies | 9-20 |
| Pathogenic repeat copies | ≥120 |
| Gene | XYLT1 |
| Repeat location | promoter |
| Chromosome locus | chr16:17470910-17470937 (-) |
| Repeat conservation | Repeat Conservation from UCSC Genome Browser |
| Toxic cause | RNA |
| Possible toxicity | Baratela-Scott syndrome (BSS) is a rare, autosomal-recessive disorder characterized by short stature, facial dysmorphisms, developmental delay, and skeletal dysplasia caused by pathogenic variants in XYLT1. A pathogenic GGC repeat expansion in the annotated XYLT1 promoter region associated with hypermethylation of exon 1 in eight of ten families with BSS with single or no known XYLT1 variants. The hypermethylated and expanded alleles show reduced expression and account for half of the disease alleles. |
| Pathway annotation | Reactome, KEGG |
| PMID | 30554721 |
| Authors | Amy J LaCroix, Deborah Stabley, Rebecca Sahraoui, Margaret P Adam, Michele Mehaffey, et al. |
| Title | GGC Repeat Expansion and Exon 1 Methylation of XYLT1 Is a Common Pathogenic Variant in Baratela-Scott Syndrome |
| Journal | American Journal of Human Genetics |
| Year | 2019 |