A novel variant in BMPR1B causes acromesomelic dysplasia Grebe type in a consanguineous Moroccan family: Expanding the phenotypic and mutational spectrum of acromesomelic dysplasias

Congenital hallux valgus occurs in Fibrodysplasia Ossificans Progressiva and BMPR1B-associated dysplasia: an important distinction

BACKGROUND

Fibrodysplasia Ossificans Progressiva (FOP; OMIM #135100) is an ultrarare genetic disorder characterised by congenital bilateral hallux valgus (CBHV), intermittent soft tissue swellings and progressive heterotopic ossification. We report a three-month-old girl with great toe abnormalities similar to FOP, in whom comprehensive clinical workup and genetic investigations illustrates an alternative diagnosis.

CASE PRESENTATION

A three-month-old girl presented with CBHV. The antenatal period was unremarkable, she was born by spontaneous vaginal delivery with an uneventful subsequent course, except for maternal concern of her bent toes which received reassurance from several health professionals. Her mother's persisting concerns were explored via the internet and social media leading her to request referral to an expert bone centre for consideration of FOP. On examination, she was thriving, there was no dysmorphism, subcutaneous lumps, skeletal or extra-skeletal deformity except for shortened great toes with lateral deviation of the proximal and distal phalanges. FOP was a feasible diagnosis, for which CBHV is highlighted as an early sign. A cautionary potential diagnosis of FOP was counselled, including advice to defer intramuscular immunisations until genetic results available. Genetic investigation was undertaken through rapid whole genomic sequencing (WGS), with analysis of data from a skeletal dysplasia gene panel, which demonstrated no ACVR1variants. The only finding was a heterozygous variant of unknown significance in BMPR1B (c1460T>A, p.(Val487Asp)), which encodes a bone morphogenic receptor involved in brachydactyly syndromes A1, A2 and D and acromesomelic dysplasia 3 (only the latter being an autosomal recessive condition).

CONCLUSION

This report highlights that CBHV serves as a vital diagnostic indicator of FOP and affected infants should be considered and investigated for FOP, including precautionary management whilst awaiting genetic studies. The second educational aspect is that CBHV may not represent a generalised skeletal disorder, or one much less significant than FOP. Receptor-ligand BMP and Activins mediated interactions are instrumental in the intricate embryology of the great toe. Recognition of non-FOP conditions caused by alterations in different genes are likely to increase with new genomic technology and large gene panels, enhancing understanding of bone signaling pathways.

Germline genetic variants in Turkish familial multiple myeloma/monoclonal gammopathy of undetermined significance cases

Multiple myeloma (MM) is a haematological malignancy primarily affecting the elderly, with a striking male predilection and ethnic disparities in incidence. Familial predisposition to MM has long been recognized, but the genetic underpinnings remain elusive. This study aimed to investigate germline variants in Turkish families with recurrent MM cases. A total of 37 MM-affected families, comprising 77 individuals, were included. Targeted next-generation sequencing analysis yielded no previously reported rare variants. Whole exome sequencing analysis in 11 families identified rare disease-causing variants in various genes, some previously linked to familial MM and others not previously associated. Notably, genes involved in ubiquitination, V(D)J recombination and the PI3K/AKT/mTOR pathway were among those identified. Furthermore, a specific variant in BNIP1 (rs28199) was found in 13 patients across nine families, indicating its potential significance in MM pathogenesis. While this study sheds light on genetic variations in familial MM in Turkey, its limitations include sample size and the absence of in vivo investigations. In conclusion, familial MM likely involves a polygenic inheritance pattern with rare, disease-causing variants in various genes, emphasizing the need for international collaborative efforts to unravel the intricate genetic basis of MM and develop targeted therapies.