The majority of SRD5A2 mutations are missense mutations but small deletions, splice junction mutations, and gross deletions were also observed. Mutations result in a spectrum of activity effects ranging from destabilizing 5αR2 to complete loss of activity.SRD5A2 mutations are inherited in an autosomal recessive pattern. Homozygous defects are more common than compound heterozygous ones. A phenotype-genotype correlation is not known to exist for many of the most common mutations, and affected males with the same 5αR2 mutations have variable phenotypes suggesting other interacting genetic factors that determine phenotype. Diagnosis
Diagnosis is usually made between birth and puberty. Pseudovaginal perineoscrotal hypospadias presenting with female appearing genitalia and pubertal virilization is the classical syndrome attributed to 5αR2D, but modern diagnostic methods can diagnose the deficiency shortly after birth and recognize the broad spectrum of presentation.The initial diagnosis of 46,XY DSD is indicated by overt genital abnormality. The objective clinical evaluation of dysmorphic features to diagnose 46,XY DSD for apparent female genitalia include: enlarged clitoris, posterior labial fusion, and inguinal/labial mass. For apparent male genitalia:  nonpalpable testes, micropenis, isolated perineal hypospadias, or mild hypospadias with undescended testis. Family history and prenatal history are also taken into account in evaluation. Karyotyping and SRY gene analysis on samples from peripheral leukocytes will exclude sex chromosome abnormalities.
Spherocytes are not as flexible as normal RBCs and will be singled-out for destruction in the red pulp of the spleen as well as other portions of the reticuloendothelial system. The red blood cells trapped in the spleen cause the spleen to enlarge, leading to the splenomegaly often seen in these patients.There are two models for this: the hapten model and the autoantibody model. The hapten model proposes that certain drugs, especially penicillin and cephalosporins, will bind to certain proteins on the red cell membrane and act as haptens (small molecules that can elicit an immune response only when attached to a large carrier such as a protein; the carrier may be one that also does not elicit an immune response by itself). Antibodies are created against the protein-drug complex, leading to the destructive sequence described above. The autoantibody model proposes that, through a mechanism not yet understood, certain drugs will cause antibodies to be made against red blood cells which again leads to the same destructive sequence. It is possible for it to occur in an immunocompromised patient. Diagnosis
Diagnosis is made by a positive direct Coombs test, other lab tests, and clinical examination and history. The direct Coombs test looks for antibodies attached to the surface of red blood cells. Clinical findings
Laboratory findings include severe anemia, normal MCV (mean corpuscular volume), and hyperbilirubinemia (from increased red cell destruction) that can be of the conjugated or unconjugated type. Treatment
Corticosteroids and immunoglobulins are two commonly used treatments for warm antibody AIHA. Initial medical treatment consists of prednisone.