Maternal folate polymorphisms and the etiology of human nondisjunction

Attempts to identify genetic contributors to human meiotic nondisjunction have met with little, if any, success. Thus, recent reports linking Down syndrome to maternal polymorphisms at either of two folate metabolism enzymes, methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR), have generated considerable interest. In the present report, we asked whether variation at MTHFR (677C-->T) or MTRR (66A-->G) might be associated with human trisomies other than trisomy 21. We analyzed maternal polymorphisms at MTHFR and MTRR in 93 cases of sex-chromosome trisomy, 44 cases of trisomy 18, and 158 cases of autosomal trisomies 2, 7, 10, 13, 14, 15, 16, 18, or 22, and compared the distributions of genotypes to those of control populations. We observed a significant increase in the MTHFR polymorphism in mothers of trisomy 18 conceptuses but were unable to identify any other significant associations. Overall, our observations suggest that, at least for the sex chromosomes and for a combined set of autosomal trisomies, polymorphisms in the folate pathway are not a significant contributor to human meiotic nondisjunction.

BRCA1 and BRCA2 protein expressions in an ovotestis of a 46, XX true hermaphrodite

BRCA1 and BRCA2 breast cancer susceptibility genes encode proteins, the normal cellular functions of which are complex and multiple, and germ-line mutations in individuals predispose both to breast and to ovarian cancer. There is nevertheless substantial evidence linking BRCA1 and BRCA2 to homologous recombination and DNA repair, to transcriptional control and to tissue proliferation. There is controversy regarding the localization of BRCA1 and BRCA2 proteins to either nucleus or cytoplasm and whether the expression is present in premeiotic germ cells or can still be expressed in mitotic spermatogonia. We report herein an immunohistochemical study of BRCA1 and BRCA2 distribution in a rather unusual tissue (an ovotestis), which addresses this issue.

Evaluation of the norrie disease gene in a family with incontinentia pigmenti

Incontinentia pigmenti (IP) is an ectodermal multisystem disorder which can affect dental, ocular, cardiac and neurologic structures. The ocular changes of IP can have a very similar appearance to the retinal detachment of X-linked familial exudative vitreoretinopathy, which has been shown to be caused by the mutations in the Norrie disease gene. Therefore, it is of interest to determine whether similar mutations in the gene can account for the retinal pathology in patients with IP. To test our hypothesis, we have analyzed the entire Norrie disease gene for a family with IP, by single strand conformational polymorphism followed by DNA sequencing. The sequencing data revealed no disease-specific sequence alterations. These data suggest that ocular findings of IP are perhaps associated with different genes and there is no direct relationship between the genotype and phenotype.

Current understanding of androgenetic alopecia. Part I: etiopathogenesis

Androgenetic alopecia (AGA) is the most common type of hair loss in men and women. This continuous process results in a type of alopecia that follows a definite pattern in those individuals who are genetically predisposed. At present the predisposing genes are unknown but the relatively strong concordance of the degree of baldness in fathers and sons is not consistent with a simple Mendelian trait and a polygenic basis is therefore most likely. AGA can be defined as a DHT-dependent process with continuous miniaturization of sensitive HF. Today we do not understand the molecular steps involved in androgen-dependent beard growth versus androgen-dependent hair loss in AGA. However, recent experimental and clinical advances enable us to explain some pathogenetic steps leading to androgenetic hair loss. Among other steroidogenic isoenzymes such as 17b- and 3b- hydroxysteroid dehydrogenases, the type 2 5a-reductase within the dermal papilla plays a central role by the intrafollicular conversion of T to DHT.

DNA methylation of the X chromosomes of the human female: an in situ semi-quantitative analysis

We present an in situ semi-quantitative analysis of the global DNA methylation of the X chromosomes of the human female using antibodies raised against 5-methylcytosine. The antibodies were revealed by immunofluorescence. Images were recorded by a CCD camera and the difference in intensity of fluorescence between active (early replicating) and inactive (late-replicating) X chromosomes was measured. Global hypomethylation of the late-replicating X chromosomal DNA was observed in three cases of fibroblast primary cultures that were characterized by numerical and structural aberrations of the X chromosomes [46,X,ter rea(X;X), 48,XXXX and 46, X,t(X;15)]. In these cases, the difference between early and late-replicating X chromosomes was significantly greater than the intra-metaphasic variations, measured for a pair of autosomes, that result from experimental procedures. In cells with normal karyotypes, the differences between the two X chromosomes were in the range of experimental variation. These results demonstrated that late replication and facultative heterochromatinization of the inactive X are two processes that are not related to global hypermethylation of the DNA.

Prenatal testosterone levels in XXY and XYY males

It has been postulated that behavioural differences between normal males and those with an additional X or Y chromosome may be related to pre- or postnatal hormonal variations. The prenatal hormone status was investigated using amniotic fluid obtained at antenatal diagnosis between 16 and 20 weeks gestation from fetuses with sex chromosome abnormalities and from controls of the same gestational age. After log transformation, the (geometric) mean testosterone levels were XY 439.4 pmol/l, range 165-1,027 (n = 29), XYY 490.7 pmol/l, range 224-1,092 (n = 20); and XXY 419 pmol/l, range 87-1,021 (n = 20). There were no significant differences between the three male groups and all three were significantly higher than the XX fetuses at 147.0 pmol/l, range 41-474 (p < 0.001). These findings give no support to the hypothesis that prenatal testosterone levels contribute to later behavioural characteristics.

Sites of transcription of the Müllerian inhibiting substance gene in mouse testis

We have examined the transcription of Müllerian inhibiting substance (MIS) in testis by the sensitive technique of reverse transcription polymerase chain reaction (RTPCR). A developmental study of testis by this nonquantitative technique showed expression at all postnatal stages, including adults while liver and kidney provided negative controls. Cell separation studies indicated that highly purified interstitial cells, as well as less homogeneous Sertoli cell-enriched and germ cell-enriched fractions, contained RNA for MIS. The transcription of MIS in an interstitial cell type was confirmed by finding MIS mRNA in purified Leydig cells. Inasmuch as the germ cell-enriched fraction contains some Sertoli cells, and XX,Sxra and XX,Sxrb which have germ cell-depleted testes, contain MIS mRNA, a Sertoli cell source remains likely for the seminiferous tubule compartment.

Hormonal and molecular genetic findings in 46,XX subjects with sexual ambiguity and testicular differentiation

Ten patients were studied who had sexual ambiguity having in common a 46.XX karyotype and testicular tissue. They were aged from one month to 23 years; some of them were followed through puberty. Eight cases were sporadic and two familial. They were divided into two groups according to finding of surgery and histology: 46, XX males with sexual ambiguity and 46 XX true hermaphrodites (TH). They were no differences in phenotypes (except uterus and ovotestis in TH). The endocrinological data were identical in the two groups: testosterone levels were in the normal range during puberty, then decreased in adulthood. Gonadotrophins were above the normal range at mid-puberty. Gonadal biopsies, regardless of the ovarian part of the ovotestis, were identical in two groups, i.e., normal in the youngest patients, then spermatogonia disappeared afterwards and dysgenesis became obvious. In one case, the ovarian zone of the ovotestis was only detected on serial cuts after gonadectomy. Southern blots displayed the presence of Y specific material in tow cases (PABY-SRY-PO.9). Otherwise, in all other patients, there was the lack of any Y sequences without any differences between the two groups. These data suggests that 46, XX males with sexual ambiguity and 46 XX true hermaphrodites may be alternative expressions of two genetic defects: one, a minimal interchange between Yp and Xp, another, a mutation of an autosomal testis determining factor for the patients without Y detectable material.

Cartilage response to thyroid hormones in the sex-linked dwarf chicken

1. Trachea cartilages were dissected from normal and dwarf chickens which had been injected with thyroxine (T4, 200 micrograms/kg) or triiodothyronine (T3, 200 micrograms/kg) for seven consecutive days, and were analysed for nucleic acids, proteins and polyamines. 2. In saline-injected control chickens, RNA, but not DNA and protein, concentration of the cartilage was higher in dwarfs than in normals. The concentration of putrescine was lower in dwarfs than in normals, while that of spermine was the reverse. 3. Thyroid hormones, especially T3, tended to increase concentrations of RNA, spermidine and spermine, and to decrease that of putrescine. However, there were no clear differences in the response to hormones between breeds.

Calorimetric and electron spin resonance examination of lipid phase transitions in human stratum corneum: molecular basis for normal cohesion and abnormal desquamation in recessive X-linked ichthyosis

Lipids appear to play a critical role as regulators of stratum corneum desquamation. In this study, we observed discrete lipid phase transitions at physiologic temperatures in both normal human scale (NHS) and in lipid extracts of NHS by differential scanning calorimetry. In contrast, such thermal transitions were not observed in recessive x-linked ichthyosis scale (RXLIS). To gain further insight into the molecular basis of the lipid phase transitions in NHS vs. RXLIS, comparable samples were evaluated by electron spin resonance, utilizing the perdeuterated probe, di-t-butyl nitroxide. Upon electron spin resonance analysis, both NHS and RXLIS demonstrated thermal phase transitions in the physiologic range; however, the nature of the lipid environments in each type varied. Whereas the environment of the spin probe was more polar in NHS than in RXLIS, the spin probe partitioned into a more "fluid" environment in RXLIS; i.e., the spin probe was more mobile in RXLIS than in NHS lipid matrices. Because an alteration in the cholesteryl sulfate:cholesterol ratio is the primary lipid abnormality in RXLIS, model cholesterol-fatty acid-cholesteryl sulfate mixtures were prepared in proportion to the lipid composition of NHS and RXLIS. Differences were observed in both thermal transitions and in lipid microenvironments in these mixtures that paralleled those observed in scale samples. Based on these results, a model is proposed that invokes abnormal hydrogen bonding, due to increased cholesteryl sulfate, as the mechanism for the abnormal desquamation in recessive X-linked ichthyosis.

Amniotic fluid-AFP in Down syndrome and other chromosome abnormalities

80.2 Per cent of 111 Down syndrome pregnancies had anmiotic fluid (AF) alpha fetoprotein (AFP) levels on or below the median and 10.8 per cent at or below 0.5 MoM compared with 41.9 and 1.4 per cent of controls. These differences were even more striking when the gestational age was less than 18 weeks compared with greater than or equal to 18 weeks. No such association was seen for other chromosome abnormalities including trisomy 18,45,X and mosaics, 47,XXY,47,XXX, and other structural abnormalities and triploidy, even when high levels due to defects such as omphalocele and cystic hygroma were excluded. All cases of trisomy 13 and 80 per cent with 47,XYY had AF-AFP levels above the median. Selection of cases for karyotyping by a low level of AF-AFP would clearly fail to detect aneuploidies other than Down syndrome and is not recommended. A possible weak association between low maternal serum (MS) and AF-AFPs in Down syndrome was most evident at less than 18 weeks, suggesting that MS screening between 16 and 18 weeks may be the most informative time.

The relative intranuclear positions of Barr bodies in XXX non-transformed human fibroblasts

The extent to which chromosomes exist in an ordered three-dimensional arrangement within the interphase nucleus remains unknown. As a means of tackling this issue we have developed simple statistical methods to test whether the positions of any intranuclear markers are mutually correlated. Applying these methods to non-transformed XXX human fibroblasts as a test case, we have examined the relative nuclear locations of the two Barr bodies in 2C cells of this type. Our results show that while individual Barr bodies have a highly non-random intranuclear distribution, segregating preferentially at the nuclear periphery in a plane parallel to the plane of cell growth (i.e., the substrate surface) and bisecting the nucleus, no evidence was found of any significant correlation between the positions of the two Barr bodies within a given nucleus.

Brain lipids of a myelin-deficient rabbit mutant during development

The paralytic tremor (pt) rabbit, a neurological mutant, exhibits hypomyelination transmitted in X-linked recessive fashion. This rabbit mutant was used for regional lipid analyses of different brain structures during development. There was a significant decrease of myelin-specific lipids, particularly in the cerebroside and sulfatide in pt rabbits. The decrease of phospholipid and cholesterol was relevant to the total lipids depletion. The molar ratio of galactolipid to phospholipid decreased in the pt rabbit brain in each age group examined. The other lipids typical for myelin, such as ethanolamine glycerophospholipids, sphingomyelin, and GM1 ganglioside, were also diminished in the myelin-rich structures, but were not changed in the cortical gray matter of pt rabbits. In contrast, the total amount of gangliosides was near control levels and, therefore, in the mutant rabbits, the white matter and brain stem contained a higher proportion of lipid, as ganglioside, relative to the control animals. This result suggests that neuronal membranes were not involved in this pathology. The characteristic biochemical abnormalities exhibited in the pt rabbit suggest that a defect of oligodendroglial cell function is primarily responsible for the myelin abnormality.

Enhanced sensitivity of lymphoblastoid cells from individuals carrying the mutation for the fragile X syndrome to the clastogenic effects of FUdR

Individuals known to carry the mutation for the fragile X syndrome can sometimes be identified cytogenetically by the presence of a fragile site on the X chromosome at q27.3. The frequency of cells bearing this fragile site is known to be enhanced by culturing the cells in folic acid deficient medium and/or by introducing folic acid metabolism inhibitors such as FUdR. In this study FUdR induction of chromosomal aberrations other than the fragile X was investigated. Lymphoblastoid cells from an obligate carrier, a mentally retarded male and a control were cultured in folic acid deficient medium in the presence of FUdR and harvested at various times after culture initiation. The frequency of chromosome and chromatid breaks was found to be higher in cells from the individuals carrying the mutation for the fragile X syndrome. The frequency of micronuclei, an indirect index of chromosome breakage, was also more elevated in cells from these individuals than in cells from the control. These findings are of potential importance to carrier detection of this common genetic disorder.

Thymidylate metabolism in fragile X syndrome cells

The observation that decreased thymidylate supply in vitro induces the expression of the Xq27 chromosome fragile site prompted us to examine cellular thymidylate metabolism. Using a sensitive enzyme assay for deoxyribonucleotide triphosphates, we found that the total cellular thymidine triphosphate pools in cell lines from fragile X patients and carriers do not differ from normal controls under either basal or folate-deficient conditions. This agrees with our earlier observation that the thymidylate synthase enzyme activities in crude cell extracts of five fragile X syndrome lymphoblast lines do not differ from those in normal controls under standard assay conditions. Although a difference in the amount of thymidine triphosphate available at the replication fork for DNA synthesis remains a possibility, our results indicate that a readily demonstrable defect in thymidylate metabolism is not present in fragile X syndrome cells.

Endocrine and immunogenetic evaluation of an XX male infant with perineoscrotal hypospadias

To clarify the origin of the genital ambiguity occasionally associated with the XX male syndrome, a series of endocrinological studies were undertaken in an affected 6 months old infant with perineoscrotal hypospadias. The patient fulfilled all the diagnostic criteria of the syndrome: the testes were descended bilaterally, the Mullerian derivatives were absent, the 46,XX chromosome complement was ascertained in different cell lines, and male levels of H-Y antigen were detected in cultured skin fibroblasts. Circulating gonadotrophin levels and pituitary LRH responsiveness were within normal limits for the age group. Serum testosterone (T) levels were normal, and gonadal stimulation with hCG caused a significant rise on serum T. Incubations of [3H]T with fibroblasts from genital skin revealed normal activity of steroid 5 alpha-reductase. Moreover, normal concentrations of thermostable cytosol androgen receptors were revealed in cultured fibroblasts. Altogether the results indicated that ambiguity of the external genitalia in this patient was the result of neither abnormal T biosynthesis, peripheral A-ring T reduction, nor androgen intracellular specific binding, and suggested that the nature of the incomplete virilization could be a non-endocrine independent event associated to this disorder. The data are also consistent with the notion that testicular impairment observed in adult XX males develops later in life.

Investigation of the mechanism for abnormal renal 25-hydroxyvitamin D3-1-hydroxylase activity in the X-linked Hyp mouse

Renal mitochondria from mutant hypophosphatemic male mice (Hyp/Y) fed a vitamin D-deficient, low calcium diet synthesize significantly less 1,25-dihydroxyvitamin D3 than mitochondria from normal male (+/Y) littermates on the same diet. Kinetic studies reveal that maximum velocity (Vmax) for 25-hydroxyvitamin D3-1-hydroxylase (1-hydroxylase) is lower in Hyp/Y relative to +/Y mice (0.21 +/- 0.02 vs. 1.06 +/- 0.12 pmol/mg protein X min) whereas the apparent Michaelis-Menten constant (Km) for the reaction is not different in both genotypes (0.55 +/- 0.05 vs. 0.50 +/- 0.08 microM). The presence of an inhibitor for 1-hydroxylase activity in renal mitochondria of Hyp/Y mice was ruled out by estimating enzyme activity in mixtures of renal mitochondria from +/Y and Hyp/Y mice. Phosphate in the incubation medium stimulated 1-hydroxylase activity in +/Y mitochondria. In Hyp/Y mice, the stimulation achieved was smaller in magnitude and the added phosphate did not restore mutant 1-hydroxylase activity to normal. The vitamin D-deficient, low calcium diet led to a significant and comparable increase in serum PTH and urinary excretion of cAMP in +/Y and Hyp/Y, suggesting that the mutant strain had an appropriate PTH response to the diet-induced fall in serum calcium. Furthermore, the fractional excretion index of phosphate which is significantly greater in Hyp/Y than +/Y mice fed the control diet increased 3-fold in both genotypes fed the vitamin D-deficient, low calcium diet. These results suggest that the abnormal renal 1-hydroxylase response in Hyp mice is not the result of generalized renal resistance to PTH in the mutant strain and suggest that the defect in Hyp/Y mice may reside at a regulatory step subsequent to cAMP production.

Lignoceric acid is oxidized in the peroxisome: implications for the Zellweger cerebro-hepato-renal syndrome and adrenoleukodystrophy

The deficient oxidation and accumulation of very-long-chain fatty acids in the Zellweger cerebro-hepato-renal syndrome (CHRS) and X chromosome-linked adrenoleukodystrophy (ALD), coupled with the observation that peroxisomes are lacking in CHRS, prompted us to investigate the subcellular localization of the catabolism of lignoceric acid (C24:0). Peroxisomal and mitochondrial-rich fractions were separated from rat liver crude mitochondria by sucrose density gradient centrifugation. Enzyme activity for the oxidation of [1-14C]palmitic acid to water-soluble acetate was 2- to 3-fold higher in the mitochondrial than in the peroxisomal-rich fraction whereas [1-14C]lignoceric acid was oxidized at a 2- to 3-fold higher rate in the peroxisomal than in the mitochondrial fraction. Moreover, unlike palmitic acid oxidation, lignoceric acid oxidation was not inhibited by potassium cyanide in either rat liver fractions or human skin cultured fibroblasts, showing that lignoceric acid is mainly and possibly exclusively oxidized in peroxisomes. We also conducted studies to clarify the striking phenotypic differences between CHRS and the childhood form of ALD. In contrast to CHRS, we found normal hepatocellular peroxisomes in the liver biopsy of a childhood ALD patient. In addition, in the presence of potassium cyanide, the oxidation of palmitic acid in cultured skin fibroblasts was inhibited by 62% in control and X chromosome-linked ALD patients compared with 88% in CHRS and neonatal ALD. This differential effect may be related to differences in peroxisomal morphology in those disorders.

In vitro reversal of fragile-X expression by exogenous thymidine

A virtually thymidine free medium was used to test the effects of exogenous thymidine on lymphocyte expression of the fragile-X. De novo pathway thymidylic acid synthesis in the cells was blocked by FUdR. Our results suggest that in vitro exogenous thymidine is directly responsible for suppressing expression of the fragile-X. More importantly, delayed addition of exogenous thymidine can negate fragile-X expression after it has first been induced by FUdR.

Folate metabolism in cells from fragile X syndrome patients and carriers

The in vitro folate sensitivity of the fragile site at Xq27 and the claims of a beneficial response of patients given folic acid prompted us to examine the folate metabolism in cells cultured from fragile X syndrome patients and carriers. Using Epstein-Barr virus we established permanent lymphoblastoid lines from 4 fragile X syndrome males and 3 carriers from 7 families. All these lines expressed the fragile site when 0.1 microM 5-fluorodeoxyuridine (FUdR) was added to the cultures 24 hr prior to harvest; thus, the lines seemed suitable for seeking an intrinsic defect. Fragile X syndrome patient and carrier lines and normal control cell lines did not differ in regard to folate requirement for growth, the ability to use homocysteine in place of methionine, the ability to utilize reduced folates as the sole folate source, or methotrexate sensitivity. These results suggest that no intrinsic defect in folate metabolism is present in fragile X syndrome cells.

Intracellular folate distribution in cultured fibroblasts from patients with the fragile X syndrome

Altered folate metabolism has been suggested as a possible reason for expression of the fragile X chromosome in low-folate medium. However, there were no significant differences in the total folate content or in the distribution of folate cofactors between fibroblasts from patients with the fragile X chromosome and those of controls both before and after a period of folate starvation. Fragile X and control fibroblasts lose folate at an equivalent rate. Insofar as folate content and distribution reflect a primary abnormality of folate metabolism, there appears to be no such abnormality in the fragile X syndrome.

Specific terminal DNA replication sequence of X chromosomes in different tissues of a live-born triploid infant

Using the thymidine pulse method, DNA replication kinetics were studied on cells derived from cartilage, gonad, lymphocytes, and skin of a live-born triploid (69,XXY) infant with typical clinical findings. Replication studies showed that 3% of the lymphocytes had one early and one late replicating X, and 97% of the lymphocytes, and cartilage, gonad, and skin cells had two early replicating X's. Asynchronous DNA replication between the two early replicating X's was observed in all tissues (range 25-40%). The predominant terminal replication sequence of X chromosomes from chondrocytes, gonad, and skin fibroblast differed from that of the lymphocytes. Thus, a tissue-specific DNA replication pattern of the early-replicating X chromosome may be present. In every tissue, the last band to complete DNA replication was Xq21. Polymorphisms of metaphase chromosomes of parents and the patient were studied by Q-banding. The possible origin of the extra haploid set of chromosomes is discussed.

Primary biochemical defect in copper metabolism in mice with a recessive X-linked mutation analogous to Menkes' disease in man

The defect in Menkes' disease in man is identical to that in Brindled mice. The defect manifests itself in a accumulation of copper in some tissues, such as renal, intestinal (mucosa and muscle), pancreatic, osseous, muscular, and dermal. Hence a fatal copper deficiency results in other tissues (e.g., hepatic). The copper transport through the intestine is impaired and copper, which circumvents the block in the copper resorption, is irreversibly trapped in the above-mentioned, copper accumulating tissues where it is bound to a cytoplasmatic protein with molecular weight 10,000 daltons, probably the primary cytoplasmatic copper transporting protein. This protein shows a Cu-S absorption band at 250 nm, and the copper:protein ratio is increased. Such copper rich protein was found neither in the kidneys of the unaffected mice nor in the liver of the mice that do have the defect. Three models of the primary defect in Menkes disease are proposed.

Biogenic amines in 47, XYY syndrome

47, XYYs represent a high percentage of patients admitted in security settings for aggressiveness. By using a polygraphic technique and amine metabolite estimation in the cerebrospinal fluid (CSF), an attempt was made to evaluate the functional activity of the central aminergic system of these patients. No drastic change was observed in sleep patterns of XYYs. The estimation of CSF amine metabolites revealed a normal value for homovanillic acid, but a significant decrease of 5-hydroxyindoleacetic acid turnover.

BrdU-33258 Hoechst analysis of DNA replication in human lymphocytes with supernumerary or structurally abnormal X chromosomes

BrdU-33258 Hoechst techniques have been used to characterize DNA replication patterns in lymphocytes from hunam females with supernumerary or structurally abnormal X chromosomes. Fluorescence analysis permits identification of late replicating X chromosomes in a very high proportion of cells and affords a high resolution method for determining the interchange points of X-X and X-autosome translocations. Asynchrony among terminal replication patterns of multiple late replicating X chromosomes within an individual cell can occasionally be demonstrated. The arms of isochromosomes usually exhibit symmetrical fluorescence patterns, with replication terminating in bands Xq21 and Xq23 (predominant pattern) or in bands Xq25 and Xq27 (alternative pattern) in both arms. In the vast majority of lymphocytes containing a balanced X-13 or X-19 translocation, the normal X is late replicating. However, DNA synthesis in the translocation products occasionally appears somewhat delayed relative to that expected for an early replicating X, consistent with possible position effects on replication kinetics.

Total body potassium content in males with X and Y chromosome abnormalities

Total body potassium has been measured in chromatin positive males (Klinefelter's syndrome) and males with a 47,XYY karyotype. In patients with an extra X chromosome the level of potassium was very significantly less than in normal males. Its concentration referred to lean body mass, estimated from the patient's height and weight, was also greatly reduced and not significantly different from values found in normal women. In 47,XYY males individual values were low but there was no reduction in the mean value for the group if allowance was made for the obesity of some XYY subjects. The significance of these findings, however, is difficult to assess as their height frequently exceeded that of the controls on which the predicted potassium values were based. From these findings it would seem that when characteristics which are normally associated with the female sex occur in males, as in Klinefelter's syndrome, there is also a reduction in body potassium either in the total content or the lean tissue concentration, or in both. By comparison, 47,XYY males appear to be more normal in these respects but further normal data is required in order to interpret the results. The possibility that abnormal androgen production in the chromatin positive men may be influencing the potassium levels is the subject of further investigation.

Dihydrotestosterone formation in cultured human fibroblasts. Comparison of cells from normal subjects and patients with familial incomplete male pseudohermaphroditism, Type 2

The conversion of [1,2-3H]testosterone to [3H]dihydrotestosterone has been assessed in fibroblast monolayers grown from skin biopsies of foreskin, scrotum, and various nongential skins from 31 control men who varied in age from newborn to 25 years and three 46,XY subjects with hereditary male pseudohermaphroditism. Under the standardized conditions utilized in this study, the rate of dihydrotestosterone formation was greater in fibroblasts grown from genital skin (foreskin and scrotum) passages exhibit the same differentiation in dihydrotestosterone formation as the skin from which the fibroblasts were grown. Furthermore, 5alpha-reductase, the enzyme that converts testosterone to dihydrotestosterone, exhibits apparent similar substrate specificity in control foreskin fibroblasts and in the foreskin itself. Fibroblasts grown from the foreskin of two patients with familial incomplete male pseudohermaphroditism, type 2, an autosomal recessive disorder of phenotypic sexual differentiation, showed a marked deficiency in the capacity to form dihydrotestosterone. In contrast, fibroblasts grown from the scrotum of one 46,XY male with familial incomplete male pseudohermaphroditism, type 1, an apparent X-linked disorder of phenotypic sexual differentiation, formed dihydrotestosterone at a normal rate.

An XX male: cytogenetic and endocrine studies

A 3 year old black male with ambiguous genitalia had a 46, XY karyotype in a bone marrow culture and an intermediate buccal smear result, suggestive of a mosaic of chromatin positive and chromatin negative cells. Upon re-evaluation at age 15 years, he has a 30% positive buccal smear and a 46, XX karyotype in cultures of peripheral blood lymphocytes, skin fibroblasts, bone marrow, and testis. No Y-body fluorescence was detectable in interphase cells from the testicular biopsy or the various cultures. The testicular biopsy appeared similar to that of XXY males, and primary hypogonadism was documented by elevated LH (107 mIU/ml) and FSH (57 mIU/ml) levels in conjunction with low testosterone (142 ng/100 ml). Administration of hCG produced qualitatively normal acute responses of testosterone and estrogens. The cytogenetic data provide support for the theory that at least some XX males once had a Y-containing cell line which was subsequently lost.

Hereditary defect of intestinal iron transport in mice with sex-linked anemia

Iron transport by everted duodenal sacs in vitro was studied in mice with sex-linked anemia (gene symbol sla) (an inherited iron deficiency anemia), in normal mice, and in normal mice on iron-deficient and iron supplemented diets. Although the over-all mucosal uptake of iron was the same in sla and normal sacs, transport of iron to the inside of the sac was much decreased in sla. The iron transport defect in sla was emphasized by the fact that genotypically normal mice on an iron-deficient diet demonstrated greatly increased iron transport. Electrophoretic analysis of protein extracted from sla and normal sacs showed only one iron-binding fraction. The sla and normal fractions had the same mobility and corresponded in position to the major band of horse ferritin. It thus appears that the iron deficiency of sla is due to a genetically determined defect in mucosal iron transport and that this defect is not associated with any demonstrable abnormality of a major iron-binding protein.