We present a large, ten-generation family of 273 individuals with 84 people having preaxial polydactyly/triphalangeal thumb due to a pathogenic variant in the zone of polarizing activity regulatory sequence (ZRS) within the exon 5 of LMBR1. The causative change maps to position 396 of the ZRS, located at position c.423 + 4909C > T (chr7:156791480; hg38; LMBR1 ENST00000353442.10; rs606231153 NG_009240.2) in the intron 5 of LMBR1. The first affected individual with the disorder was traced back to mid-1700, when some settlers and workers established in Cervera de Buitrago, a small village about 82 km North to Madrid. Clinical and radiological studies of most of the affected members have been performed for 42 years (follow-up of the family by LFGA). Molecular studies have confirmed a pathogenic variant in the ZRS that segregates in this family. To the best of our knowledge, this is the largest family with preaxial polydactyly/triphalangeal thumb reported so far.
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http://dx.doi.org/10.1002/ajmg.a.62994 | DOI Listing |
Am J Med Genet A
January 2023
CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain.
We present a large, ten-generation family of 273 individuals with 84 people having preaxial polydactyly/triphalangeal thumb due to a pathogenic variant in the zone of polarizing activity regulatory sequence (ZRS) within the exon 5 of LMBR1. The causative change maps to position 396 of the ZRS, located at position c.423 + 4909C > T (chr7:156791480; hg38; LMBR1 ENST00000353442.
View Article and Find Full Text PDFBMJ Case Rep
August 2016
Department of Orthopaedics, Kasturba Medical College, Manipal University, Manipal, Karnataka, India.
Tibial hemimelia is a rare congenital limb deficiency which is characterised by a hypoplastic/aplastic tibia. It actually represents a spectrum of anomalies, ranging from mild hypoplasia of the tibia to total absence of the tibia. Several classifications based on radiological description exist in the literature.
View Article and Find Full Text PDFAm J Med Genet A
July 2013
Department of Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
The ZRS (zone of polarizing activity regulatory sequence) is a long-range limb-specific Sonic Hedgehog (SHH) enhancer. In humans, the ZRS is located in chromosome 7q36 within intron 5 of LMBR1; approximately 1 Mb telomeric of SHH. Point mutations and duplications of the ZRS lead to a variable phenotype of preaxial polydactyly/triphalangeal thumb, tibial hypoplasia, radial ray deficiency, and type IV familial syndactyly (syndactyly of all digits with polydactyly).
View Article and Find Full Text PDFEur J Hum Genet
June 2010
Human Molecular Genetics Laboratory, Health Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan.
A cis-regulatory sequence also known as zone of polarizing activity (ZPA) regulatory sequence (ZRS) located in intron 5 of LMBR1 is essential for expression of sonic hedgehog (SHH) in the developing posterior limb bud mesenchyme. Even though many point mutations causing preaxial duplication defects have been reported in ZRS, the underlying regulatory mechanism is still unknown. In this study, we analyzed the effect on transcription factor binding of a novel ZRS point mutation (463T>G) in a Pakistani family with preaxial polydactyly and triphalangeal thumb.
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