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| 1. |
X-linked genetic disorders and male infertility |
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The man has only one X chromosome. This means that an X-linked recessive disorder will be manifest in males, and that the defect will be transmitted to his daughters but notto his sons. |
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| 2. |
Kallmann's syndrome |
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Kallmann's syndrome is the commonest X-linked disorder in infertility practice. The predominant form is X-linked recessive caused by a mutation in the KALlG-1 gene on Xp 22.3 [13]. Rarer forms of Kallmann's syndrome include an autosomal-dominant form [14]. Patients with Kallmann's syndrome have hypogonadotrophic hypogonadism and may have other clinical features, including anosmia, facial asymmetry, cleft palate, colour blindness, deafness, maldescended testes and renal abnormalities. |
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It is important to note that some men with Kallmann's syndrome have an isolated gonadotrophin deficiency without any other phenotypic abnormalities. These patients may present de novo with infertility, which can be treated successfully by hormone replacement therapy. |
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| 3. |
Androgen insensitivity: Reifenstein's syndrome |
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The rare disorder of androgen insensitivity may first present with infertility. The condition has X-linked recessive inheritance due to a defect in the androgen receptor gene located on Xq 11-12. The phenotype varies widely, from complete testicular feminization to an apparently normal man with infertility, although the latter is rare. |
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A structured genetic search for androgen deficiency was conducted among men with high testosterone and low sperm counts. No cases were found using base-pair mismatch analysis technology [15]. Several de-novo mutations of the androgen receptor were noted; in all cases, these were associated with obvious genital abnormalities such as hypospadias. It was concluded that androgen insensitivity in the infertile male in the absence of any genital abnormality is rare. |
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| 4. |
Other X-disorders |
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A case report exists of an azoospermic man with biopsy-proven spermatogenetic arrest, who was found to have a submicroscopic interstitial deletion on the Xp pseudoautosomal region in peripheral blood and skin fibroblast samples. Other genetic and chromosomal examinations were entirely normal, including probing of the Yq region [16]. There is also a report about two men with azoospermia and X pseudoautosomal deletions [17). |
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