UNSW Embryology
DEVELOPMENT OF THE REPRODUCTIVE SYSTEM
XX MALE SYNDROME
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278850 XX MALE SYNDROMEtable OF CONTENTSDatabase Links"8 MEDLINE Citations" "Coriell Cell Line Repository" Note: pressing the
TEXTMaleness is normally inherited as a dominant
trait; a single copy of the Y chromosome induces
testicular differentiation of the embryonic gonad.
(See SRY (480000)
for discussion of a gene product implicated in this
process.) The mechanism of masculinization in
occasional persons with an apparently normal female
chromosome complement (and a Klinefelter phenotype)
has been thought to be due to reciprocal X-Y
interchange at paternal meiosis (Ferguson-Smith,
1966). In Finland, de la
Chapelle et al. (1978) observed three XX males
in one pedigree consistent with autosomal recessive
inheritance. All three XX males and their mothers
were found to have H-Y antigen and their fathers
appeared to have excess H-Y antigen. The data were
interpreted as indicating that the H-Y structural
loci constitute a family of testis-determining
genes and that either dominant or recessive modes
of XX sex reversal can be produced by Y-autosome
(or Y-X) translocations, depending upon the
particular portion of H-Y genes transferred.
Cytogenetic evidence of structural abnormality of
Xp was presented by Evans et
al. (1979) but could not be corroborated by
de la Chapelle et al.
(1979). Pierella et al.
(1981) suggested the existence, at least in
some cases, of an autosomal mutation that causes
inactivation of a subterminal portion of Xp which
normally escapes inactivation. The suggestion was
based on the demonstration of male levels of
steroid sulfatase in 2 affected cousins who could
not share the same X chromosome because they were
related through their fathers and their paternal
grandfathers. An autosomal factor influencing sex
determination, H-Y antigen production, Xg
expression, and steroid sulfatase levels can be
understood if its effects are mediated via
autosomal control of inactivation of a distal
segment of Xp. Autosomal control of X inactivation
may be suggested by the presence of more than one
active X per cell in tetraploids and some
triploids. There is probably pathogenetic
heterogeneity in the category of XX males. Using a
Y-specific DNA clone for in situ hybridization
studies, Andersson et al.
(1986) demonstrated transfer of Y-material to
the end of Xp in 3 XX males. By study of XX males
with translocation of material from Yp onto Xp, and
by study of XY females with deletion of part of the
short arm of the Y chromosome, Simpson
et al. (1987) were able to separate the genetic
loci for the H-Y antigen and for testis-determining
factor (TDF). H-Y maps to the centromeric region or
the proximal part of the long arm of the Y
chromosome, whereas TDF maps more distally on the
short arm of the Y chromosome. The H-Y gene may be
identical to or near a spermatogenesis factor on
the long arm of the Y chromosome which maps to the
same area. The existence of factors controlling
spermatogenesis on the nonfluorescent part of the
long arm of Y (distal part of Yq11) was suggested
by study of 6 men with deletion of this segment and
azoospermia (Tiepolo and
Zuffardi, 1976). In mice, H-Y (or a closely
linked gene) has been implicated in spermatogenesis
(Burgoyne et al., 1986).
REFERENCES
CLINICAL SYNOPSIS
CREATION DATEVictor A. McKusick : 6/4/1986
EDIT HISTORYmark : 1/13/1998 |
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