Localization of an acromesomelic dysplasia on chromosome 9 by homozygosity mapping

Novel bilateral symmetrical congenital transverse upper and lower limb deficiencies in siblings in Ethiopia: two case reports

Background

Transverse congenital limb deficiency is a common limb deficiency where there is normal limb development until a certain point, beyond which no anatomical structure exists. Typically, this presents as an isolated and spontaneous abnormality as a result of arrest during limb bud development. Transverse bilateral deficiency in both upper and lower limbs is not well described.

Case presentation

We report the cases of two female Ethiopian amhara siblings, aged 6 years and 5 months, respectively, from Ethiopia with similar transverse bilateral upper and lower limb deficiencies. The sisters were born from the same parents and have similar phenotypic presentations. Neither of them have other syndromic features or systemic manifestations. The siblings are currently on follow-up and are receiving assistance by specialist orthotists, who are working to improve walking and also providing adaptive equipment to facilitate self-care and feeding.

Conclusion

The relationship of the patients and the similarity of phenotypical presentations suggests a strong genetic link.

The Regulation of Growth in Developing, Homeostatic, and Regenerating Tetrapod Limbs: A Minireview

The size and shape of the tetrapod limb play central roles in their functionality and the overall physiology of the organism. In this minireview we will discuss observations on mutant animal models and humans, which show that the growth and final size of the limb is most impacted by factors that regulate either limb bud patterning or the elongation of the long bones. We will also apply the lessons that have been learned from embryos to how growth could be regulated in regenerating limb structures and outline the challenges that are unique to regenerating animals.

Analogs of C-type natriuretic peptide as a potential new non-surgical treatment strategy in knee osteoarthritis

Osteoarthritis (OA) is a common, chronic, progressive, and multifactorial musculoskeletal system disease affecting millions of people around the world. Despite the use of several treatment modalities, the search for a disease modifying drug continuous. Recent evidence suggest involvement of C-type natriuretic peptide (CNP) signaling in induction of chondroprotective pathways. A CNP analog (BMN 111) with an extended plasma half-life due to its neutral-endopeptidase resistance has shown to be pharmacologically active in achondroplasia enabling to hypothesize that BMN 111 may also be used as a treatment strategy in OA, in which CNP signaling has been suggested to be protective and/or reparative.

Acheiropodia is caused by a genomic deletion in C7orf2, the human orthologue of the Lmbr1 gene

Acheiropodia is an autosomal recessive developmental disorder presenting with bilateral congenital amputations of the upper and lower extremities and aplasia of the hands and feet. This severely handicapping condition appears to affect only the extremities, with no other systemic manifestations reported. Recently, a locus for acheiropodia was mapped on chromosome 7q36. Herein we report the narrowing of the critical region for the acheiropodia gene and the subsequent identification of a common mutation in C7orf2-the human orthologue of the mouse Lmbr1 gene-that is responsible for the disease. Analysis of five families with acheiropodia, by means of 15 polymorphic markers, narrowed the critical region to 1.3 cM, on the basis of identity by descent, and to <0.5 Mb, on the basis of physical mapping. Analysis of C7orf2, the human orthologue of the mouse Lmbr1 gene, identified a deletion in all five families, thus identifying a common acheiropodia mutation. The deletion was identified at both the genomic-DNA and mRNA level. It leads to the production of a C7orf2 transcript lacking exon 4 and introduces a premature stop codon downstream of exon 3. Given the nature of the acheiropodia phenotype, it appears likely that the Lmbr1 gene plays an important role in limb development.