MIRAGE Syndrome

Clinical characteristics: MIRAGE syndrome is an acronym for the major findings of myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy. Cytopenias are typically seen soon after birth; thrombocytopenia is the most common followed by anemia and pancytopenia. Recurrent infections from early infancy include pneumonia, urinary tract infection, gastroenteritis, meningitis, otitis media, dermatitis, subcutaneous abscess, and sepsis. Reported genital phenotypes in those with 46,XY karyotype included hypospadias, microphallus, bifid shawl scrotum, ambiguous genitalia, or complete female genitalia. Hypoplastic or dysgenetic ovaries have been reported in females. Gastrointestinal complications include chronic diarrhea and esophageal dysfunction. Moderate-to-severe developmental delay is reported in most affected individuals. Autonomic dysfunction and renal dysfunction are also reported.

Diagnosis/testing: The diagnosis of MIRAGE syndrome is established in a proband with suggestive findings and a heterozygous germline gain-of-function pathogenic variant in SAMD9 identified by molecular genetic testing.

Management: Treatment of manifestations: Individuals with severe anemia and thrombocytopenia due to bone marrow failure should be treated with standard transfusion approaches; bacterial infection prevention including antibiotic prophylaxis and fever precautions in individuals with severe neutropenia. Individuals with severe neutropenia and chronic transfusion requirements, along with individuals who develop monosomy 7 myelodysplastic syndrome should be considered for hematopoietic stem cell transplantation. Standard treatment of infections with antibiotics, antiviral or antifungal agents as needed; consider prophylactic intravenous immunoglobulin if endogenous immunoglobulin levels are low; management by nutritionist to ensure adequate caloric intake and to assist with elemental diet for chronic diarrhea; hydrocortisone and fludrocortisone as needed for adrenal hypoplasia; surgical removal of dysgenetic gonads or surgical intervention may be considered for those with external genital anomalies; consider duodenal tube feeding in those with recurrent aspiration pneumonia; early intervention with occupational, physical, speech and feeding therapy for developmental delay; artificial tear solutions and treatment per ophthalmologist for ocular manifestations of autonomic dysfunction such as hypolacrima; management of ambient temperature for those with temperature instability; management of renal dysfunction per nephrologist.

Surveillance: Complete blood count with differential every four to six months; annual bone marrow aspirate and biopsy (with analysis for somatic alterations including chromosome 7 abnormalities) in those with cytopenias including anemia, thrombocytopenia, or neutropenia; at least annual assessment of height, weight, head circumference, physical examination for features of adrenal hypoplasia, and measurement of serum sodium, potassium, glucose, cortisol, and ACTH. Assess for diarrhea, feeding issues, and esophageal dysfunction as needed; monitor developmental milestones every three to six months in the first year of life and at least annually thereafter; assess for keratoconjunctivitis sicca, corneal ulcer, and temperature instability as needed; at least annual measurement of serum creatinine, blood urea nitrogen, and urinalysis to evaluate renal function.

Evaluation of relatives at risk: It is appropriate to clarify the genetic status of apparently asymptomatic at-risk relatives of an affected individual in order to identify as early as possible those who would benefit from evaluation for myelodysplasia.

Genetic counseling: MIRAGE syndrome is an autosomal dominant disorder typically caused by a de novo pathogenic variant. Rarely, individuals diagnosed with MIRAGE syndrome have the disorder as the result of a variant inherited from a heterozygous parent with no apparent features of MIRAGE syndrome. If the proband has an SAMD9 pathogenic variant that is not detected in the leukocyte DNA of either parent, the recurrence risk to sibs is slightly greater than that of the general population because of the possibility of parental germline mosaicism or the possibility of a false negative result in a parent due to preferential loss of the chromosome with the SAMD9 pathogenic variant. Once the SAMD9 pathogenic variant has been identified in an affected family member, prenatal and preimplantation genetic testing are possible.