Seven families with RUS and blood problems were studied, totaling nine affected people with issues ranging from a single low blood cell line to full bone marrow failure. Three different germline changes in the MECOM gene (two new) were found in five of these families, while two families had no detectable changes in MECOM or HOXA11. The cases show that the same MECOM variant can cause very different severities and ages of onset, and that RUS with blood problems is often a broad bone marrow failure syndrome rather than just low platelets.
A large family with CRUS across three generations was described, with several members in each generation affected. Pedigree analysis supported autosomal dominant inheritance with variable expression, meaning some relatives had more severe deformity than others. The report highlights that CRUS can run strongly in families and that genetic counseling may be useful for affected kindreds.
A 4‑year‑old girl with bilateral CRUS was described, with limited forearm rotation but enough shoulder and wrist motion to manage most daily tasks. The report links the deformity to a timing error in early limb development and reviews how the bones normally separate before birth. Because function was acceptable, treatment was observation and follow‑up rather than surgery, showing that some children with CRUS can be managed without an operation.
Children and adults with RUS but normal blood counts were found to have specific changes in the MECOM gene, focusing on one hotspot amino acid (R781) in the EVI1 protein. Different changes at this same spot caused a wide range of bone findings, from isolated RUS to more complex limb differences. The study shows that MECOM‑related disease can appear without obvious blood problems, so genetic testing is useful even when only RUS is present.
A newborn with very low platelets had bilateral radio‑ulnar synostosis and bent little fingers, and later work linked this pattern to mutations in the HOXA11 gene in similar patients. The report discusses how the same syndrome combines bone changes in the forearm with failure of megakaryocytes, causing severe thrombocytopenia. Management focused on treating the blood problem (including transfusions and monitoring) while the synostosis itself was observed rather than operated on in the neonatal period.
An African American child with radioulnar synostosis and low platelets (thrombocytopenia) was found to have a MECOM gene variant. The case supports that MECOM‑related disease can combine forearm bone fusion with serious blood problems, fitting into the RUSAT spectrum. Management focused on monitoring and treating the blood disorder rather than operating on the synostosis.
Families with radioulnar synostosis plus serious blood problems were found to carry germline MECOM variants affecting the EVI1 protein, defining a syndrome called RUS with hematologic disease (RUSHD). The same MECOM change could cause very different marrow problems, from mild single low blood counts to severe bone marrow failure needing transplant, and onset ranged from infancy to adulthood. Management focused on monitoring and treating the marrow failure (often with bone marrow transplant), while the forearm fusion itself was not always operated on.
People with SMAD6 gene changes often had RUS, sometimes with other bone differences in the skull or spine. SMAD6 loss‑of‑function variants were much more common in people with RUS than in healthy controls, showing this gene is a major cause of the condition. Many affected people had stable bone changes without life‑threatening illness, so care usually focused on watching growth and function rather than routine surgery.
Four unrelated people with RUS and other bone differences were found to have damaging changes in the AUTS2 gene. AUTS2 disruption affected gene networks that guide early bone development, linking this gene directly to abnormal limb patterning. The study identifies AUTS2 as another key RUS gene alongside NOG, MECOM, and SMAD6.
A child with bilateral radio‑ulnar synostosis and extra minor anomalies was evaluated for an underlying genetic cause. Chromosome studies and further genetic testing were performed and showed an unbalanced chromosomal change involving deletion and duplication segments. The report links this chromosomal imbalance to both the limb findings and other physical differences, and recommends genetic counseling for the family.
The study links changes in the GREM1-FMN1 gene region to limb malformations, including forms of syndactyly and Cenani-Lenz-like hand and foot differences. It shows that these genomic rearrangements can either delete or duplicate regulatory DNA elements, which alters normal gene activity during limb development. The findings also support that disruption of this locus represents a shared genetic mechanism underlying several related limb malformation patterns.
One child with radioulnar synostosis and multiple brain abnormalities is described, carrying a 17q21.31 microdeletion involving the EFTUD2 gene. Facial differences, growth problems, and developmental delay are present along with limb changes. The report links this combination of findings to a rare craniofacial syndrome and expands the known features associated with EFTUD2-related conditions.
A specific MECOM missense mutation linked to radioulnar synostosis with amegakaryocytic thrombocytopenia was modeled in mice to test its effects on blood formation. Heterozygous mutant mice showed low platelet counts and reduced hematopoietic stem and progenitor cells but did not develop radioulnar synostosis. These findings indicate that this mutation mainly acts as a loss-of-function allele in hematopoiesis and help explain how MECOM variants cause bone marrow failure in this syndrome.
Two boys from related parents each had a harmful change in the SMAD6 gene plus both skull bone fusion and forearm bone fusion. One boy also had learning and development problems, but neither had heart or major vessel defects on heart ultrasound. Lab tests showed that the SMAD6 changes made the protein work less well, so bone growth signals were not properly “braked,” helping explain why these bone fusions happened.
A family with several members having both radioulnar synostosis and severe low platelet counts (congenital amegakaryocytic thrombocytopenia) is described, and all affected people share a mutation in the HOXA11 gene. The combination of arm bone fusion and blood problems defines a new inherited syndrome tied to this gene change. The report shows that HOXA11 is important not only for limb development but also for forming the cells that make platelets in the bone marrow.
An infant presented with proximal radioulnar synostosis together with severe bone marrow failure causing low blood counts. Genetic testing did not find a HOXA11 mutation, showing that other genes besides HOXA11 can cause this combination of arm bone fusion and marrow failure. Supportive care and hematology follow-up were required, and the case broadened the known spectrum of radioulnar synostosis with bone marrow disease.
A Chinese boy presented with congenital proximal radioulnar synostosis together with amegakaryocytic thrombocytopenia, and genetic testing revealed a novel missense mutation in the MECOM gene. The child had very low platelets and bone marrow showing markedly reduced megakaryocytes, consistent with an inherited bone marrow failure syndrome. This report expands the known spectrum of MECOM-associated radioulnar synostosis with thrombocytopenia (RUSAT type 2) and underscores the need for genetic evaluation when limb malformations coexist with cytopenias.
A 27‑year‑old man had congenital radioulnar synostosis together with complete absence of sperm and testicular dysfunction. Chromosome analysis showed a pseudodicentric Y chromosome, linking this structural Y‑chromosome abnormality with both the limb finding and infertility. This report expands the chromosomal abnormalities known to be associated with this skeletal pattern and male infertility.
This report describes a boy with radioulnar synostosis who was also found to have the XYY chromosome pattern. The combination shows that this bone difference can appear together with a sex chromosome change. The case adds to evidence that extra Y chromosomes may be linked with certain limb and growth differences.
Radioulnar synostosis is described together with blood problems like low platelets and bone marrow failure, and with specific gene changes. Known links include variants in the MECOM gene and named syndromes where arm bone changes occur with serious blood count problems. The article groups these medical and genetic findings to show how arm bone fusion and blood diseases are connected in several inherited conditions.
A 7-year-old boy had fusion of one forearm and a special Y chromosome called isodicentric Y. Growth and development were otherwise normal, and no other major birth differences were present. The case adds another example of a Y-chromosome structural change found together with this bone pattern.
These summaries are a starting point, not medical advice or a substitute for reading each paper. Study methods, quality, and conclusions vary. Follow the source link for the full publication and discuss personal medical questions with a qualified clinician.
