It is possible for diseases to occur in different organ systems as part of a SAMD9 deficiency.
Hematological abnormalities – transient or persisting thrombocytopenia and/or anemia – usually occur during infancy and generally regress spontaneously. In addition, there may be mild lymphopenia, with a few patients developing leukopenia. It is rare for myelodysplastic syndrome (MDS) to develop.
In nearly all patients diagnosed to date, severe and sometimes recurring infections have developed, often in the form of sepsis, meningitis, or systemic mycosis. Recurring viral or bacterial infections may occur as well. It is not uncommon for severe infections to have a lethal outcome before the patient reaches the age of two.
Characteristics of patients with a SAMD9 mutation are; retarded longitudinal growth and low body weight, both prenatally as well as postnatally. In a few patients, there are also intellectual and/or motor developmental delays.
Parathyroid hypoplasia, often described as being part of an SAMD9 mutation, is generally evident due to hyperpigmentation of the skin even before the onset of salt depletion symptoms. Parathyroid hypoplasia has so far been diagnosed in all patients who have undergone an ultrasound examination.
All patients with a male karyotype have exhibited retardation of genital development in the form of micropenis, cryptorchidism, hypospadias, and even extending to entirely female external genitalia. In patients with a female karyotype, there may be hypoplastic or dysgenetic ovaries with only a few primordial follicles. The ovaries may be completely absent as well.
Enteropathy as part of a SAMD9 mutation manifests with chronic diarrhea and dilatation of the colon. There may be gastroesophageal reflux as well.
In addition, open ductus arteriosus, absent or hypoplastic thymus, recurring urinary tract infections, and skeletal abnormalities (congenital scoliosis, radial clubhand, overlapping fingers, clubfeet, congenital flat feet) have also been described.