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From the Clinical Research Centers |
-Reductase-2 and 17ß-Hydroxysteroid Dehydrogenase-3 Gene Defects in Male Pseudohermaphrodites from a Turkish Kindred1
Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Cornell University Medical College (S.C., Y.-S.Z., L.-Q.C., Q.L., M.D.K., J.I.-M.), New York, New York 10021; Medical Service, Veterans Administration Medical Center (S.A.), East Orange, New Jersey 07019; and Children’s Hospital Oakland Research Institute (C.H.L.S.), Oakland, California 94609
Address all correspondence and requests for reprints to: Dr. Julianne Imperato-McGinley, Division of Endocrinology, Diabetes, and Metabolism, New York Hospital-Cornell Medical Center, 1300 York Avenue, Box 149, Room F-263, New York, New York 10021.
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Abstract |
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 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
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-reductase-2
(SRD5A2) or 17ß-hydroxysteroid dehydrogenase-3
(17ßHSD3) gene defects. Using single strand DNA
conformational polymorphism analysis and DNA sequencing, a new mutation
in exon 5 of SRD5A2 gene was detected in certain male
pseudohermaphrodites from this kindred. This single base deletion
(adenine) resulted in a frame shift at amino acid position 251
resulting in the addition of 23 amino acids at the carboxyl-terminal of
this 254-amino acid isozyme. Transfection expression of the mutant
isozyme in CV1 cells showed a complete loss of enzymatic activity in
the conversion of [14C]testosterone to
dihydrotestosterone, without a change in the messenger ribonucleic acid
level compared to that of the wild-type isozyme. Analysis of the
17ßHSD3 gene in other male pseudohermaphrodites from
this kindred revealed a single point mutation (G
A) at the
boundary between intron 8 and exon 9, disrupting the splice acceptor
site of exon 9. In this kindred, in addition to the identification of male pseudohermaphrodites with either a homozygous SRD5A2 or 17ßHSD3 gene defect, other male pseudohermaphrodites were found to be genetically more complex: e.g. homozygous for the SRD5A2 defect and heterozygous for the 17ßHSD3 defect, or homozygous for the 17ßHSD3 defect and heterozygous for the SRD5A2 defect. Also, phenotypically normal carriers were identified with either one or both gene defects.
Homozygous male pseudohermaphrodites with SRD5A2 or
17ßHSD3 gene defects were phenotypically
distinguishable by the presence of mild gynecomastia in the latter.
Hormone data were consistent with the particular homozygous gene
defect. In summary, we show 1) the novel existence of two gene defects,
SRD5A2 and 17ßHSD3, each causing MPH
within a large isolated Turkish kindred; 2) that the two defects
segregate independently and may be inherited from two different
progenitors; and 3) analysis of a new mutation in exon 5 of
SRD5A2 gene, supporting the functional importance of the
carboxyl-terminal of 5-reductase-2 isozyme.
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Introduction |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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and 2). Some of the affected males had
5-reductase-2 (5-RD-2; gene SRD5A2) deficiency,
whereas others had 17ß-hydroxysteroid dehydrogenase 3 (17ßHSD-3;
gene 17ßHSD3) deficiency.
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-RD-2 deficiency in several male
pseudohermaphrodites was previously established biochemically by an
elevated plasma testosterone (T) to dihydrotestosterone (DHT) ratio
coupled with increased urinary C19 and C21
5ß/5-steroid metabolite ratios (3, 4, 5). Intermediate elevations of
urinary C19 and C21 5ß/5-steroid
metabolite ratios identified heterozygous individuals. The biochemical
diagnosis of 17ßHSD deficiency in other affected male
pseudohermaphrodites was based on elevated ratios of plasma
androstenedione (
4) to T (3, 6). Heterozygosity for
17ßHSD-3 deficiency, however, could not be demonstrated with this
methodology. This paper identifies gene defects for both SRD5A2 and 17ßHSD3 within this kindred. Homozygous and genetically complex heterozygous subjects are also described. In addition to molecular genetic studies of this large kindred (3, 5), affected subjects and families not yet connected to the master pedigree are described.
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Subjects and Methods |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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Twenty-one subjects (nine male pseudohermaphrodites, five
phenotypically normal males, and seven phenotypically normal females),
as shown in Table 1 and Figs. 1
and 2,
were studied. All participants provided written informed consent. This
study was approved by the institutional review board of the New York
Hospital-Cornell Medical Center.
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), and D-II-5 (Fig. 2) have
clinical and biochemical evidence of steroid 5-RD-2 deficiency and
were evaluated previously as subjects adult-1, adult-2, child-7, and
child-8, respectively (5). Subject A-V-1 (Fig. 1) is subject IV-7 in
the previously published study and has clinical and biochemical
evidence of 17ßHSD-3 deficiency (3) (Table 1). His mother (subject
A-IV-7) is subject III-1 from the previous study (3). The clinical
features of these male pseudohermaphrodites were described previously
(3, 5). A-IV-3 is a 45-yr-old subject, born with ambiguous genitalia and raised as a female, although known in the community as an affected child. The subject did not change to a male gender role at puberty and remains the only known affected person not to do so in the community. A moderate amount of facial hair was present. Blood and urine samples were provided, but a physical examination was declined.
A-VI-8 is a 46-yr-old male pseudohermaphrodite who was raised as a female, but changed to a male gender role at puberty. He supposedly underwent unsuccessful corrective genital surgery 20 years ago. On physical examination he had penoscrotal hypospadias and a phallus with a stretched length of 3 cm. His left testis was in the inguinal canal, and the right testis was in the scrotum (10 and 15 mL, respectively). He had a deep voice, but no acne or temporal hair line recession.
Subject B-III-7 is a 6-month-old child, who was recognized to be a male pseudohermaphrodite at birth by his family and is being raised as a male. He had perineoscrotal hypospadias, a bifid scrotum and a right scrotal testis. The left testis could not be palpated. Phlebotomy was not possible due to poor venous access.
C-II-8 is a 23-yr-old male pseudohermaphrodite, who was raised as a female. At puberty there was no breast development or menstrual periods. There was clitoral enlargement, a muscular body habitus, and deepening of the voice. A gender role change to male occurred during this time. On physical examination there was moderate facial and body hair, a female escutcheon, and no evidence of acne or temporal hair line recession. There was perineoscrotal hypospadias as well as a bifid scrotum, a pseudovagina, and a right inguinal and a left scrotal testis (10 and 15 mL, respectively). His phallus measured 2 cm in length when stretched, and a chordee was present.
Subjects A-V-17, B-II-5, C-I-1, C-II-3, and C-II-6 are healthy adult males (aged 23–60 yr) from the community with normal secondary sexual characteristics and normal sexual function. Subjects B-II-6 and N1 are healthy adult females (aged 24 and 45 yr old, respectively) from the community with normal secondary sexual characteristics, reproductive function, and physical examinations. C-II-4 is a 36-yr-old woman who underwent menarche at age 14 yr and has two children. Her menstrual periods were regular, at 25-day intervals, with scanty bleeding for 3 days. Her physical examination was within normal limits. The Ferriman-Galloway hirsutism score was 3 of 11. There was no history of acne, infertility, menstrual irregularity, or hirsutism in these females. Two subjects (C-I-2 and N-2) were postmenopausal, one subject (B-III-6) was a healthy 4-yr-old girl with a normal physical examination.
Methods
Blood samples from representative members of the master pedigree
and three smaller pedigrees (see Subjects section above;
Figs. 1 & 2) were collected for molecular genetic analysis and plasma
hormone assays. Urine samples were also collected for analysis of
steroid 5ß/5 metabolites.
Plasma androgens and urinary steroid metabolites. Plasma
4, T, and DHT were measured by RIA after separation by
paper chromatography using a previously described method (7, 8).
Urinary C19 and C21 5ß/5-steroid
metabolite ratios (etiocholanolone to androsterone,
11ß-hydroxyetiocholanolone to 11ß-hydroxyandrosterone,
tetrahydrocortisol to 5-tetrahydrocortisol, and
tetrahydrocorticosterone to 5-tetrahydrocorticosterone) were
analyzed as methyloxime trimethylsilyl ether derivatives by capillary
gas chromatography, as described previously (8, 9).
PCR amplification and DNA sequencing. Blood was drawn into
ethylenediamine tetraacetate (EDTA)-containing tubes, and genomic DNA
from white blood cells was isolated by the Qiagen genomic DNA isolation
kit (Qiagen, Chatsworth, CA). The concentrations of DNA were determined
by UV absorbance. Exons 1–5 of the SRD5A2 gene (10) were
amplified and sequenced by PCR as previously described with minor
modifications (11). Briefly, PCR amplification was carried out in 25
µL containing 0.12 µg genomic DNA, 1 µmol/L of each
oligonucleotide primer, 200 µmol/L of each of four
deoxyribonucleotide triphosphates, 10 mmol/L Tris-HCl (pH 8.3), 50
mmol/L KCl, 0.1% Triton X-100, 1.5 mmol/L MgCl2, and 2.5 U
thermostable DNA polymerase (Promega, Madison, WI). For hot PCR, 10
µCi [-32P]deoxy-ATP were added to the reaction. The
samples were heated at 94 C for 2 min, and then at 94 C for 1 min, 65 C
for 1 min, and 72 C for 1 min for a total of 35 cycles; a final cycle
consisted of 72 C for 10 min.
PCR amplification and labeling of exons 1–11 of the
17ßHSD3 gene were carried out using primers and annealing
temperatures summarized in Table 2. The
reaction mixture contained 0.12 or 0.36 µg genomic DNA, 200 µmol/L
of each of four deoxyribonucleotide triphosphates, 10 mmol/L Tris-HCl
(pH 8.3), 50 mmol/L KCl, 0.1% Triton X-100, and 2.5 U thermostable DNA
polymerase. Ten microcuries of [-32P]deoxy-ATP were
added for hot PCR. The samples were denatured at 94 C for 2 min, and
then sequentially heated at 94 C for 30 s, at the annealing
temperature shown in Table 2 for 15 s, and at 72 C for 30 s
for a total of 30 or 35 cycles. A final extension cycle was performed
at 72 C for 10 min. The 17ßHSD3 gene was sequenced using
the fmol DNA sequencing kit (Promega, Madison, MI) with
32P-labeled primer (11).
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Site-directed mutagenesis and expression of 5-RD-2
isoenzymes. A plasmid (pCMV-5RD2) containing the entire
encoding region of human 5-RD-2 complementary DNA (cDNA) (12) was
obtained from Drs. Luu-The and Labrie (CHUL Research Center, Quebec,
Canada). A new subclone (pCMV-5RD2w) was constructed by insertion of
a PCR-amplified fragment of 3'-untranslated region [from 2335–2394 in
the GenBank sequence (10)] of human SRD5A2 gene to
SacI-HindIII sites of pCMV-5RD2. This new
construct, pCMV-5RD2w, was used for in vitro mutagenesis
to generate a single base deletion using Altered Sites II in
vitro Mutagenesis Systems from Promega (Madison, WI). The
sequences of all constructs were confirmed by DNA sequencing.
CV1 cells (American Type Culture Collection, Rockville, MD) were grown in DMEM supplemented with 10% FBS, 20 mmol/L L-glutamine, 50 U/mL penicillin, and 50 µg/mL streptomycin. The cells were plated on 60-mm dishes with a density of 0.4 x 106 cells/dish and transfected using the calcium phosphate precipitation method (ProFection, Promega) with 5–10 µg expression vector, 2 µg RSV-ß-galactosidase plasmid, and pBluescript-SK plasmid to total 15 µg DNA/dish as previously described (13). After 12–16 h of transfection, the cells were washed and continued to grow in fresh medium for 48 h before harvesting. The transfection efficiencies were monitored by measuring ß-galactosidase activity in the cell homogenates.
Assay of 5-RD-2 enzymatic activity. 5-RD-2 enzymatic
activity was assessed as previously described with modifications (14, 15). Briefly, the transfected cells were harvested by scraping with a
rubber policeman, pelleted by centrifugation, washed three times with
phosphate-buffered saline, resuspended in 50 mmol/L sodium phosphate
buffer (pH 7.4) containing 20% glycerol, homogenized, frozen, and
stored at -80 C until analysis. For the enzymatic assay, cell
homogenate proteins (20 µg) were incubated at 37 C for 1 h in
0.1 mol/L Tris-citrate buffer (pH 5.0), 2 mmol/L NADPH, and 5 µmol/L
[14C]T. Immediately after incubation, the steroids were
extracted in ethyl ether, dried, and resuspended in chloroform-methanol
(2:1) solution. The steroid products were separated by TLC on silica
gel A/chloroform-ethyl-acetate (5:1, vol/vol) developing system,
exposed to Kodak X-Omat film, and identified by comparison with known
standards. The conversion of T to DHT was determined by liquid
scintillation counting of radioactive steroid products.
RT-PCR analysis of messenger ribonucleic acid (mRNA) levels.
Total cellular RNA from transfected CV1 cells was extracted using
TRIzol reagents (Life Technologies, Grand Island, NY), and the
concentrations were determined by UV absorbance (13). One microgram of
total cellular RNA or pCMV-5RD2w plasmid DNA was treated with 5 U
ribonuclease (RNase)-free deoxyribonuclease I (DNase I; Promega,
Madison, WI) in 50 mmol/L Tris-HCl (pH 7.5) and 10 mmol/L
MgCl2 at 37 C for 30 min. Ten micrograms of transfer RNA
were added to the reaction as a carrier. The samples were purified by a
High Pure PCR Product Purification Kit (Boehringer Mannheim,
Indianapolis, IN), treated with 10 U RNase-free DNase I (Boehringer
Mannheim), and repurified. One tenth of each sample was subjected to
RT-PCR amplification using the Titan One Tube RT-PCR System (Boehringer
Mannheim) to quantitate the levels of 5-RD-2 mRNA in transfected
cells according to the manufacturer’s instruction with some
modifications. A pair of primers, 5'-GACATTTGTG TACTCACTGCTC-3' and
5'-CGAAGCTTCATTGACA GTTTTCATCAGCATTGTGG-3', located at the beginning of
exon 2 and the untranslated region of exon 5 of 5-RD-2 mRNA,
respectively (11), were used in amplification. The conditions of RT-PCR
amplification were: incubation of the samples at 50 C for 30 min, then
one cycle at 94 C for 2 min to denature the template, 35 cycles each of
94 C for 30 s, 60 C for 30 s, and 68 C for 45 s,
followed by a final cycle of 68 C for 5 min. One fifth of each sample
was analyzed by electrophoresis in a 1.5% agarose gel and visualized
with ethidium bromide staining.
Statistics. The 5-RD-2 enzymatic activity is presented as
the mean ± SEM percent conversion of T to DHT.
One-way ANOVA followed by post-hoc Student-Newman-Keuls test
was used to determine the difference among multiple groups.
P < 0.05 was accepted as the level for statistic
significance.
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Results |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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). Pedigrees B–D (Fig. 2) are not yet
linked to pedigree A. Table 1 summarizes the genetic, plasma, and
urinary data. SRD5A2 gene mutation
Analysis of the SRD5A2 gene by SSCP revealed a mutation
in exon 5 in subjects A-IV-20 and C-II-8, as shown in Fig. 3A. The migration pattern of radiolabeled
single stranded PCR products of affected subjects was compared with
that of normal controls (Fig. 3A, A-IV-20 and C-II-8 vs.
normal). This mutation was confirmed by DNA sequencing. As shown in
Fig. 3B, a single base, adenine, at exon 5 of the SRD5A2
gene was deleted in affected subjects, A-VI-8 and C-II-8. The remaining
four exons of the SRD5A2 gene were normal in the affected
subjects by both SSCP and DNA sequencing (data not shown).
Heterozygosity of the mutation was detected by both SSCP analysis (see
lanes C-I-1 and A-IV-7 of Fig. 3A) and DNA sequencing (see lane C-I-2
of Fig. 3B). In addition, heteroduplex formulation of double-stranded
DNA was detected in heterozygous subjects by SSCP analysis (Fig. 3A, arrowheads C-I-1 and A-IV-7).
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). The functional significance of this mutation was
assessed by in vitro mutagenesis-transfection expression in
CV1 cells. The mutation was generated in an expressible cDNA by
site-directed mutagenesis. Wild-type and mutated cDNAs in expression
vector were transfected to CV1 cells, and the enzymatic activity was
determined in the cell homogenates. As shown in Fig. 4, A and B, the conversion of
[14C]T to DHT was completely lost in the mutant isoenzyme
(only 0.5% of the wild-type isoenzyme) and was the same as that in the
nontransfected or mock-transfected controls. However, the level of
mutant SRD5A2 mRNA was comparable to that in the wild-type
isoenzyme using RT-PCR analysis (Fig. 4C).
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) were consistent with 5-RD-2 deficiency (2, 4, 16, 17, 18). As
shown in Table 1, the genetically confirmed homozygotes had high normal
plasma T levels with low plasma DHT levels, an increased T to DHT
ratio, and elevated 5ß/5-steroid metabolite ratios. The
heterozygous subjects had intermediate C19 and
C21 urinary 5ß/5-steroid metabolite ratios, consistent
with their carrier status, as previously described (3). 17ßHSD3 gene mutation
Using SSCP analysis and DNA sequencing, a single point mutation at
the boundary between intron 8 and exon 9 of 17ßHSD3 gene
was detected in subjects A-V-1 and A-IV-3. Figure 5A shows a representative SSCP,
demonstrating the distinctly abnormal migration pattern of radiolabeled
single-stranded PCR products of exon 9 of the 17ßHSD3
gene. DNA sequencing (Fig. 5B) revealed a substitution of an adenine
(A) for a guanine (G) preceding the first base of exon 9. This mutation
disrupted the splice acceptor site of exon 9 (19, 20). Heterozygosity
of this mutation was detectable by SSCP (Fig. 5A, A-IV-7) and was
confirmed by DNA sequencing (Fig. 5B, A-IV-30 and B-II-6).
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4 level (1860 ng/dL; normal male range, 50–150 ng/dL),
a decreased T level (259 ng/dL; normal male range, 300–950 ng/dL), and
an increased 4 to T ratio (7.2; normal, <0.5; Table 1),
consistent with 17ßHSD-3 deficiency (3, 19, 20). The plasma DHT
level, plasma T to DHT ratio, and ratios of urinary C19 and
C21 5ß/5-steroid metabolites were normal. A male pseudohermaphrodite homozygous for a SRD5A2 gene defect and heterozygous for the 17ßHSD3 gene defect
A novel feature of this kindred is the coexistence of two gene
mutations in the same family as well as in the same individual. Subject
A-IV-30 (Fig. 1 and Table 1) was homozygous for the SRD5A2
exon 5 mutation and heterozygous for the 17ßHSD3 gene
mutation, as determined by both SSCP and DNA sequencing.
Phenotypically, this subject did not differ from those homozygous for
the SRD5A2 gene defect. Plasma androgen levels are not
available, but urinary C19 and C21
5ß/5-steroid metabolite ratios were consistent with 5-RD-2
deficiency (Table 1).
A male pseudohermaphrodite homozygous for the 17ßHSD3 gene defect and heterozygous for a SRD5A2 gene defect
Subject A-IV-3 (Fig. 1, pedigree A) was both homozygous for the
17ßHSD3 gene defect and heterozygous for the
SRD5A2 gene mutation (Table 1). Plasma androgen levels
(Table 1) were similar to those of subject A-V-1, a homozygote for the
17ßHSD3 defect, with the exception of a slightly lower DHT
level and a slightly higher T to DHT ratio. The urinary
5ß/5-steroid metabolite ratios are compatible with heterozygosity
for 5-RD-2 deficiency (5, 18). This subject was reluctant to have a
physical examination. Thus, we cannot comment about the phenotypic
expression of this genetically complex subject.
Heterozygosity for both SRD5A2 and 17ßHSD3 gene mutations in the same individuals
Heterozygosity for both SRD5A2 and 17ßHSD3
gene defects was detected in subject A-IV-7 (the mother of subject
A-V-1, homozygous for the 17ßHSD3 gene defect), subject
B-II-6, and her daughter B-III-6 (see Subjects and
Methods, pedigrees A and B, and Table 1). These females were
fertile and had normal secondary sexual characteristics. As shown in
Table 1, their plasma 4 concentrations were within the
normal range. Their absolute plasma levels of T and DHT were variable.
However, the T to DHT ratios were elevated, and the urinary
5ß/5-steroid metabolite ratios were in the heterozygous range for
5-RD-2 deficiency.
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Discussion |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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-RD-2 deficiency is newly described. A single base (adenine)
deletion at exon 5 of the SRD5A2 gene caused a frame shift
at amino acid position 251, adding 23 amino acids to the
carboxyl-terminal of the 254-amino acid isozyme. This carboxyl-terminal
mutation resulted in complete loss of enzymatic activity without
altering the level of gene expression in transfection analysis. Other
studies indicate that mutations of the carboxyl-terminal of this
isozyme decrease both cofactor (NADPH) binding and substrate binding
(21). However, decreases in cofactor and substrate binding alone cannot
entirely account for the overwhelming loss of enzymatic activity of
this mutant enzyme, because high concentrations of NADPH and T were
used in the assay, and further increases in cofactor and substrate
concentrations (5-fold higher) did not improve the enzymatic activity
of the mutant enzyme (data not shown). Additional mutations of the
SRD5A2 gene in Turkish and Mediterranean subjects are
summarized in Table 3.
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A, 655-1) in the boundary between intron 8
and exon 9 that disrupts the splice acceptor site for exon 9 and alters
the sequence of the enzyme (19, 20). This mutation has previously been
reported in two subjects of Mediterranean descent: a Greek American and
a Syrian (19, 20). Other mutations of the 17ßHSD3 gene
identified in 17ßHSD-deficient subjects from the eastern
Mediterranean and Middle East include a missense mutation in exon 2
(S65L) and a missense mutation in exon 3 (R80Q) (19, 20). As the two genes are located on different chromosomes (SRD5A2 on chromosome 2 and 17ßHSD3 on chromosome 9), they segregate independently during meiosis (22). Therefore, combinations of homozygosity and/or heterozygosity for the two gene defects are possible in the same individual within this kindred. Not surprisingly, we have detected genetically complex male pseudohermaphrodites: one who is homozygous for a SRD5A2 gene mutation and heterozygous for the 17ßHSD3 gene defect, one who is homozygous for the 17ßHSD3 gene defect and heterozygous for a SRD5A2 gene mutation, and three females who are compound heterozygotes for the two enzyme defects. To date, a male pseudohermaphrodite who is homozygous for the two gene defects has not been detected.
The phenotypes of the male pseudohermaphrodites with either of the two enzyme defects from this community are similar. Wolffian-derived structures (epididymis, vasa deferentia, seminal vesicles, and ejaculatory ducts) are present, with a clitorus-like phallus and a blind vaginal pouch within a urogenital sinus (2, 23). The testes are either descended or located in the inguinal canal. At puberty, virilization of the external genitalia with deepening of the voice and increased musculature occurs, frequently followed by a gender change from female to male. The subjects with the 17ßHSD3 gene defect develop mild gynecomastia at puberty and have slightly increased facial and body hair (3, 19).
There are at least five isozymes of 17ßHSD in the human (23, 24). The
17ßHSD-3 isozyme is expressed in the testes and is responsible for
MPH due to 17ßHSD deficiency (19, 20). The type 1 17ßHSD isozyme
mainly catalyzes the conversion of estrone (E1) to
estradiol (E2). Types 3 and 5 are the rate-limiting enzymes
in T biosynthesis. Types 2 and 4 predominantly affect T and
E2 inactivation. The ontogeny of these five isozymes in
human tissues has not been studied. However, the fact that adults
homozygous for a 17ßHSD3 gene defect have ambiguous
genitalia suggests that 17ßHSD-3 is the primary isozyme expressed
early in utero and is responsible for T biosynthesis from
4 during the critical period of sexual differentiation.
At puberty, the expression of the other 17ßHSD isozymes in the
peripheral tissues compensates to some extent for testicular 17ßHSD-3
deficiency, resulting in significant pubertal masculinization.
MPH in this community has been known to occur for at least seven
generations spanning over 100 yr (5). The elders state that their
ancestors came from Konya, in the central Anatolian plateau of present
day Turkey. The village is 1800 meters above sea level and has a
population of less than 3000. It was an isolated area until 25 yr ago,
when dirt roads were built, and electric and telephone lines were
established. The inhabitants are shepherds and farmers who work
seasonally along the Mediterranean coast. Affected children are
currently recognized at birth, given male names, and raised as boys. In
the past, affected babies were raised as girls, and after a pubertal
gender change, the community would call them kiz-o
lan (girl-boy)
and regard them as incomplete men.
Pedigree analysis demonstrating intermarriage suggests that a founder effect is responsible for the dissemination of genetic abnormalities within this community. The geographic isolation of this kindred is analogous to that of the large Dominican kindred with an SRD5A2 gene defect (2, 4). The coexistence of both SRD5A2 and 17ßHSD3 gene defects in this kindred may be derived from either one progenitor carrying both defects on different alleles or from two progenitors. Thus, it is possible that one gene defect was initially present in this area, and at some point later in time another progenitor introduced the second mutant gene into this population. Studies to date reveal an asymmetric distribution of the two gene defects in this kindred, i.e. there are more individuals with homozygous or heterozygous SRD5A2 gene defects than individuals with homozygous or heterozygous 17ßHSD3 gene defects identified by molecular genetic analysis. This finding supports the concept that the SRD5A2 gene defect may have been introduced first.
Our present findings support the previous demonstration that females
homozygous or heterozygous for the SRD5A2 gene defect or the
17ßHSD3 gene defect are fertile (4, 25) (Fig. 2, pedigree
C). It has been shown that the 17ßHSD3 gene is expressed
in the testes (19, 23), but not in the ovary (26). The consanguineous
marriages together with the lack of adverse expression of either of
these defects in women contributes greatly to the dissemination of both
gene defects in this community.
In summary, we have identified defects in both the 17ßHSD3 and SRD5A2 genes that are responsible for MPH in a geographically isolated large Turkish kindred. The coexistence of the two gene defects in the same individual has been identified, although homozygosity for the two gene defects in the same individual has yet to be identified. The phenotypic expression of subjects homozygous for the SRD5A2 gene defect or homozygous for the 17ßHSD3 gene defect is similar to those previously reported (2, 3, 4, 5, 19, 20). Two progenitors, each carrying one of the defects, or one progenitor with both defects could be responsible for the coexistence of the two gene defects in this kindred. Identification of unique haplotypes for the two genes may aid in the resolution of this mystery.
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Acknowledgments |
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RD2 expression vector, and to Ms. Tita Torrado for
expertly performing the plasma androgen assays. |
Footnotes |
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2 Co-first authors in alphabetical order.
Received July 24, 1997.
Revised October 2, 1997.
Accepted October 10, 1997.
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  J. W. Tomlinson, J. Finney, C. Gay, B. A. Hughes, S. V. Hughes, and P. M. Stewart Impaired Glucose Tolerance and Insulin Resistance Are Associated With Increased Adipose 11{beta}-Hydroxysteroid Dehydrogenase Type 1 Expression and Elevated Hepatic 5{alpha}-Reductase Activity Diabetes, October 1, 2008; 57(10): 2652 - 2660. [Abstract] [Full Text] [PDF]
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17{beta}-Hydroxysteroid Dehydrogenase-3 Deficiency: Diagnosis, Phenotypic Variability, Population Genetics, and Worldwide Distribution of Ancient and de Novo Mutations J. Clin. Endocrinol. Metab., December 1, 1999; 84(12): 4713 - 4721. [Abstract] [Full Text]
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H. F. L. Meyer-Bahlburg Gender Assignment and Reassignment in 46,XY Pseudohermaphroditism and Related Conditions J. Clin. Endocrinol. Metab., October 1, 1999; 84(10): 3455 - 3458. [Full Text] [PDF]
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Y.-S. Zhu, L.-Q. Cai, J. J. Cordero, W. J. Canovatchel, M. D. Katz, and J. Imperato-McGinley A Novel Mutation in the CAG Triplet Region of Exon 1 of Androgen Receptor Gene Causes Complete Androgen Insensitivity Syndrome in a Large Kindred J. Clin. Endocrinol. Metab., May 1, 1999; 84(5): 1590 - 1594. [Abstract] [Full Text]
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, Homozygous SRD5A2
gene defect; 
, heterozygous
SRD5A2 gene defect; 
,
homozygous 17ßHSD3 gene defect;
, both homozygous
SRD5A2 and heterozygous 17ßHSD3 gene
defects; 
, both homozygous
17ßHSD3 and heterozygous SRD5A2 gene
defects; 
, both
heterozygous SRD5A2 and heterozygous
17ßHSD3 gene defects; 
, 5
,
17ßHSD-3-deficient patients identified by clinical and biochemical
studies; 
, 5
