With the AMH gene mutation (PMDS Type 1), the AMH is either not produced, produced in deficient amounts, defective, secreted at the wrong critical period for male differentiation or the Müllerian ducts manifested a resistance to AMH.AMHR2 contains the instructions for generating the receptors that AMH binds to. If there if a mutation in the AMHR2 gene, the response to AMH molecules binding to the receptor cannot be properly reciprocated. Other possibilities include an absence of the receptors, such that the AMH molecules cannot induce differentiation. Mutation in the AMHR2 is critical to proper male sex differentiation. The genetic mutational cause of PMDS, is a 27 base-pair deletion of the Anti-Müllerian Type 2 Receptor gene. The 27-base-pair deletion that occurs PMDS is in exon 10 on one allele.PMDS is inherited in an autosomal recessive manner. The male individuals inherit mutated copies of the X chromosomes from the maternal and paternal genes, implying the parents are carriers and do not show symptoms. Females inheriting two mutated genes do not display symptoms of PMDS, though remain as carriers. Males are affected genotypically with the karyotype (46, XY) and phenotypically. Mechanism
AMH (anti Müllerian hormone) is produced by the primitive Sertoli cells as one of the earliest Sertoli cell products and induces regression of the Müllerian ducts. Fetal Müllerian ducts are only sensitive to AMH action around the 7th or 8th week of gestation, and Müllerian regression is completed by the end of the 9th week. The AMH induced regression of the Müllerian duct occurs in cranio-caudal direction via apoptosis.
Persistent Müllerian duct syndrome (PMDS) is the presence of Müllerian duct derivatives (fallopian tubes, uterus, and/or the upper part of the vagina)  in what would be considered a genetically and otherwise physically normal male animal by typical human based standards. In humans, PMDS typically is due to an autosomal recessive congenital disorder and is considered by some to be a form of pseudohermaphroditism due to the presence of Müllerian derivatives.Typical features include undescended testes (cryptorchidism) and the presence of a small, underdeveloped uterus in an XY infant or adult. This condition is usually caused by deficiency of fetal anti-Müllerian hormone (AMH) effect due to mutations of the gene for AMH or the anti-Müllerian hormone receptor, but may also be as a result of insensitivity to AMH of the target organ.PMDS can also present in non-human animals. Presentation
The first visible signs of PMDS after birth is cryptorchidism (undescended testes) either unilaterally or bilaterally. Along with cryptorchidism, is also inguinal hernias which may be presented unilaterally (affects one testicle) or bilaterally (affects both testicles). Adults who have been oblivious to this condition may be presented with haematuria, which is when blood appears in urine because of hormonal imbalances. PMDS Type I, is also referred to as hernia uteri inguinalis, which exhibits one descended testis that has also pulled the fallopian tube and sometimes uterus, through the inguinal canal. The descended testes, fallopian tube and uterus all fall in the same inguinal canal, causing an inguinal hernia.