A family with mental retardation, variable macrocephaly and macro-orchidism, and linkage to Xq12-q21

A family with X linked inheritance of mental retardation (XLMR) is presented. There are 10 mentally retarded males and two affected females in two generations. There are four obligatory carriers, one of whom is described as "slow". Most affected males show macrocephaly and macro-orchidism, which are typical signs of the fragile X syndrome, but have been tested cytogenetically and by analysis of the FMR1 gene and do not have this syndrome. However, some normal males in the family also exhibit macro-orchidism and macrocephaly. Linkage analysis using markers derived from the X chromosome indicates that the causative gene in this family is located in the proximal long arm of the X chromosome, in the interval Xp11-q21. Maximum lod scores of 2.96 with no recombination were found at three loci in Xq13-q21: DXS1111, DXS566, and DXS986. Recombination was observed with DXS1002 (Xq21.31) and DXS991 (Xp11.2), loci separated by about 30 Mb. Although isolation of the gene in this family will be difficult because of the size of the region involved, the localisation should be helpful in investigating other similar families with XLMR, macrocephaly, and macro-orchidism not attributable to FMR1.     

The relation between immunoglobulin G antibodies to Chlamydia trachomatis and poor ovarian response to gonadotropin stimulation before in vitro fertilization

Although several genes for mental retardation and epilepsy, including double cortex/X-linked lissencephaly (DC/XLIS), have been localized to Xq21.3-q23, there has been no complete physical map of this region available. We constructed a YAC/STS contig map by initiating two yeast artificial chromosome (YAC) walks from the markers that flanked the DC/XLIS candidate gene region. We report an approximately 4-Mb contig extending from DXS287 to DXS8088, encompassing DXS1072 and DXS1059, and composed of 52 YACs identified with 15 previously published STSs and 19 novel YAC-end STSs. This contig also contains two brain-specific genes, doublecortin (HGMW-approved symbol DCX), responsible for DC/XLIS, and PAK3, which may be responsible for neurological diseases localized to this region. The new contig extends and incorporates several previously published contigs, providing a total overlapping contig extending approximately 34 Mb from DXS441 in Xq13.1 to DXS8088 in Xq23.     

Isolation and characterization of three microsatellite markers in the proximal long arm of the human X chromosome

Three microsatellites have been identified in cosmids from the human X chromosome. The cosmids have been assigned locus numbers DXS554, DXS559, and DXS566 and have been localized to Xq12-q13 (DXS554 and DXS559) and Xq13 (DXS566). In addition, they have been genetically mapped in relation to the androgen receptor (AR), phosphoglycerate kinase 1, pseudogene 1 (PGK1P1), and phosphoglycerate kinase (PGK1) loci in the proximal long arm. Genetically, the localization of microsatellites at DXS554 and DXS566 is indistinguishable from PGK1, whereas that at DXS559 maps between AR and PGK1, close to PGK1P1. DXS566 is identical to the independently identified DXS441 marker. These markers should be useful for physical and genetic mapping in this region.     

Refining the genetic location of the gene for X linked hydrocephalus within Xq28

The most common inherited form of hydrocephalus, X linked hydrocephalus (HSAS), is characterised by mental retardation, adducted thumbs, and spastic paraplegia. Genetic analysis has mapped the locus for HSAS to subchromosomal band Xq28 within a region of approximately 2 megabases of DNA. In order to refine the location of the disease gene we have conducted genetic linkage analysis with Xq28 marker loci in four additional HSAS families. A lod score of 4.26 with polymorphic marker DXS52 (St14) confirms the linkage of HSAS to Xq28. Identification of a recombination event between the HSAS gene and Xq28 loci F8C and DXS605 (2-19) reduces the size of the interval likely to contain the disease locus to about 1.5 megabases, the distance between DXS605 and DXS52. The locus for neural cell adhesion molecule, L1CAM, maps within this interval and therefore represents a candidate gene for HSAS.     

MR findings in growth hormone deficiency: correlation with severity of hypopituitarism

BACKGROUND AND PURPOSE: Growth hormone deficiency may present as an isolated deficit (IGHD) or in association with multiple deficiencies (MPHD). Previous studies have not compared the MR imaging findings with the severity of hypopituitarism. Our purpose was to determine whether MR imaging can distinguish between IGHD and MPHD. METHODS: Forty-four patients with growth hormone deficiency who were examined by MR imaging were included in this retrospective study. On the basis of the endocrinologic findings, 21 were determined to have IGHD and 23 to have MPHD. The presence, size, location, and morphologic characteristics of the stalk, the neurohypophysis, and the adenohypophysis were recorded in each case. Findings in the two groups were compared. Statistical significance was determined by t-test. RESULTS: The stalk was normal in one patient with IGHD and in none of those with MPHD; it was truncated or thin in 19 patients with IGHD (90%) and in only one with MPHD (4%); it was absent in 22 patients with MPHD (96%) and in only one patient with IGHD (5%). These differences between the two groups were highly significant. In 81% of the IGHD patients and in 91% of the MPHD patients the location of the neurohypophysis was ectopic. This difference between the two groups was not significant. Among IGHD patients, the adenohypophysis was of normal size in 13 patients (62%), small in six (29%), and absent in two (9%); the corresponding findings in MPHD patients were seven (30%), six (26%), and 10 (44%). CONCLUSION: The majority of IGHD patients had a truncated or thin stalk and a normal or small adenohypophysis. An absent stalk and adenohypophysis are characteristic of MPHD. MR imaging can contribute to the prediction of the pattern and severity of hypopituitarism in patients with growth hormone deficiency.     

Isolated growth hormone deficiency: testing the little mouse hypothesis in man and exclusion of mutations within the extracellular domain of the growth hormone-releasing hormone receptor

The phenotypic characteristics of isolated growth hormone deficiency (IGHD) type IB in humans, such as autosomal recessive inheritance, time of onset of growth retardation, diminished secretion of growth hormone (GH) and IGF-I, proportional reduction in weight and size, and delay in sexual maturation, has much in common with the phenotype of the homozygous little/little (lit/lit) mouse. Sequencing of the GH releasing hormone (GHRH) receptor in lit/lit mice has shown a single nucleotide substitution within the extracellular peptide binding domain at codon 60 that changed aspartic acid to glycine. Therefore, the GHRH receptor is a reasonable candidate gene for causing IGHD in humans. DNA from 65 unrelated healthy Caucasians of normal stature and 65 children with IGHD type IB of whom 12 did not respond to exogenous treatment with GHRH were studied. Restriction endonuclease analysis, linkage studies, and polymerase chain reaction amplification and sequencing of the whole extracellular domain including the first three membrane spanning domains of the GHRH receptor gene were performed. None of the analyses revealed any structural abnormalities in these patients with IGHD. This suggests that a lit/lit mouse equivalent is an unlikely explanation for the majority of children with IGHD. Although gross structural abnormalities in the whole gene have been ruled out in this study, mutations in the carboxyl terminus are still possible, and, therefore, the remaining part of the gene needs to be sequenced.     

Malignant splenic lymphoma: sonographic patterns, diagnosis and follow-up

In 1972, Fried described a large Scottish family affected by X linked mental retardation (XLMR), hydrocephalus, and mild facial dysmorphism. The phenotype has considerable similarity to the MASA syndrome, which results from mutations of the L1CAM gene in Xq28, and this family has since been assumed to be an example of this condition. We have reinvestigated the family for linkage to X chromosome markers, and obtained additional clinical information on surviving affected subjects. The phenotype in these patients has evolved into a distinctive syndrome, with severe mental retardation (MR), spastic diplegia, ventricular dilatation, and calcification of the basal ganglia. Linkage to Xq28 markers has been excluded, suggesting that Fried syndrome is not allelic with MASA syndrome. Two point and multipoint linkage analysis indicates that the gene for this condition lies within the interval KAL-DXS989 in Xp22. We propose the designation Fried syndrome to emphasise the disorder's distinctive phenotype.     

Weight relative to height before and during growth hormone therapy in prepubertal children

We used the Genentech National Cooperative Growth Study database to examine differences in weight relative to height (weight for height standard deviation score or WTHTZ) in 3460 patients at enrollment and after one year of therapy with recombinant human growth hormone (rhGH), and in a subset of 450 patients treated for three years with rhGH. The major diagnostic categories were idiopathic growth hormone deficiency (IGHD), organic GH deficiency (OGHD), and idiopathic short stature (ISS). Children with IGHD and ISS were underweight for height at baseline but had a progressive increase in WTHTZ during three years of rhGH therapy. The same pattern applied to children with IGHD associated with septo-optic dysplasia and CNS trauma or infection. However, children with OGHD associated with craniopharyngiomas, other CNS tumors, leukemia, or CNS irradiation were overweight when starting rhGH and showed a decrease in WTHTZ during the first year of rhGH therapy. The increase in WTHTZ during rhGH treatment in children with ISS and OGHD suggests that the GH-induced increase in muscle mass exceeded loss of fat mass. Because children with neoplasm-related OGHD were overweight at baseline, the decline in WTHTZ during the first year of rhGH therapy suggests that loss of fat mass is the predominant effect in this subgroup.     

Childhood-onset psychosis: evolution and comorbidity

High resolution cytogenetics, microsatellite marker analyses, and fluorescence in situ hybridization were used to define Xq deletions encompassing the fragile X gene, FMR1, detected in individuals from two unrelated families. In Family 1, a 19-year-old male had facial features consistent with fragile X syndrome; however, his profound mental and growth retardation, small testes, and lover limb skeletal defects and contractures demonstrated a more severe phenotype, suggestive of a contiguous gene syndrome. A cytogenetic deletion including Xq26.3-q27.3 was observed in the proband, his phenotypically normal mother, and his learning-disabled non-dysmorphic sister. Methylation analyses at the FMR1 and androgen receptor loci indicated that the deleted X was inactive in > 95% of his mother's white blood cells and 80-85% of the sister's leukocytes. The proximal breakpoint for the deletion was approximately 10 Mb centromeric to FMR1, and the distal breakpoint mapped 1 Mb distal to FMR1. This deletion, encompassing approximately 13 Mb of DNA, is the largest deletion including FMR1 reported to date. In the second family, a slightly smaller deletion was detected. A female with moderate to severe mental retardation, seizures, and hypothyroidism, had a de novo cytogenetic deletion extending from Xq26.3 to q27.3, which removed approximately 12 Mb of DNA around the FMR1 gene. Cytogenetic, and molecular data revealed that approximately 50% of her white blood cells contained an active deleted X. These findings indicate that males with deletions including Xq26.3-q27.3 may exhibit a more severe phenotype than typical fragile X males, and females with similar deletions may have an abnormal phenotype if the deleted X remains active in a significant proportion of the cells. Thus, important genes for intellectual and neurological development, in addition to FMR1, may reside in Xq26.3-q27.3. One candidate gene in this region, SOX3, is thought to be involved in neuronal development and its loss may partly explain the more severe phenotypes of our patients.     

Loss of heterozygosity at chromosome segment Xq25-26.1 in advanced human ovarian carcinomas

To determine whether a tumor suppressor gene of importance to epithelial ovarian cancer resides on the X chromosome, we examined loss of heterozygosity (LOH) in 123 epithelial ovarian cancer cases. In 54 such cases, we examined LOH at 26 loci on the human X chromosome. In eight cases, we examined LOH in 14 loci and in 61 cases we examined LOH in 13 loci. Matched DNA samples from tumors and corresponding normal tissues were analyzed by polymerase chain reaction (PCR) amplification of microsatellite markers. Frequent losses were found in epithelial carcinomas at the Xq25-26.l region, including DXS1206 (34.5% loss in informative cases), DXS1047 (27.7%), HPRT (24.1%), and DXS1062 (33.3%). The minimum overlapping region of LOH was approximately 5 megabases (Mb), flanked by DXS1206 (Xq25) and HPRT (Xq26.1). The methylation status of the remaining allele of the androgen receptor gene in the tumors exhibiting LOH at the Xq25-26.1 region suggested that the loss was exclusively in the inactive X chromosome. We next determined whether a significant relationship exists between Xq LOH and other parameters, including histologic grade and/or clinical stage of the tumors and LOH at TP53. The Xq LOH had a significant association with grade 2 to 3 tumors at stages II to IV. Sixteen of 18 cases that showed Xq LOH revealed LOH at the TP53 locus, and 45% of tumors exhibiting LOH at TP53 showed Xq LOH. These results suggest that there may be a tumor suppressor gene or genes which escape inactivation of the X chromosome at Xq25-26.1, and that the loss of the gene(s) at Xq25-26.1 is frequently accompanied by loss of the TP53 or loss of another gene on chromosome 17. These losses may contribute to the progression from a well-differentiated to a more poorly differentiated state or to metastatic aggressiveness.     

Localization of the gene for Wieacker-Wolff syndrome in the pericentromeric region of the X chromosome

The Wieacker-Wolff syndrome (WWS, MIM* 314580), first described clinically in 1985, is an X-linked recessive disorder. In earlier studies, linkage between the WWS gene and DXYS1 at Xq21.2 and DXS1 at Xq11 as well as AR at Xq12 was reported. Here we report on a linkage analysis using highly polymorphic, short terminal repeat markers located in the segment from Xp21 to Xq24. No recombination between the WWS locus and ALAS2 or with AR (z = 4.890 at theta = 0.0) was found. Therefore, the WWS locus was assigned to a segment of approximately 8 cM between PFC (Xp11.3-Xp 11.23) and DXS339 (Xq11.2-Xq13).     

Characterization of pigmented granules in minocycline-induced cutaneous pigmentation: observations using fluorescence microscopy and high-performance liquid chromatography

Ambiguous abdominal situs, asplenia/polysplenia and severe cardiac malformations characterize heterotaxy in humans. These anomalies result from the inability of the developing embryo to establish normal left-right asymmetry. We have studied an interesting family in which the heterotaxy phenotype segregates as an X-linked recessive trait. In order to map the heterotaxy locus (HTX), we have analysed 39 family members using highly-polymorphic microsatellite markers from the X chromosome. One of these markers, DXS994, shows no recombination with the disease locus in 20 informative meioses. Linkage analysis results in a maximum lod score of 6.37. Current genetic and physical mapping data assign the order of loci in Xq24-q27.1 as cen-DXS1001-(DXS994, HTX)-DXS984-tel. These results establish the first mapping assignment of situs abnormalities in humans.     

Identification by STS PCR screening of a microdeletion in Xp21.3-22.1 associated with non-specific mental retardation

X-linked non-specific mental retardation (MRX) is a heterogeneous condition in which mental retardation (MR) appears to be the only consistent manifestation. The genetic and phenotypic heterogeneity exclude any possibility of pooling families and, therefore, of fine-mapping the related disease genes. In order to identify genomic critical regions involved in the MRX condition assigned to Xp21.3-22.1 region, we have implemented the PCR screening of non fragile X MR patients for the presence of deletions in this region. The amplification by PCR of 12 markers located between POLA and DXS704 using genomic DNA from 192 MR males led to the identification, in a 9 year old mentally retarded boy, of a microdeletion which extends from DXS1202 to DXS1065. None of the known genes, POLA, MAGE genes cluster, DAX1, GK and DMD, that map in the Xp21.3-22.1 region is affected by this deletion. This approach, which could easily be applied to several other MRX loci, allowed not only a confirmation of the presence of a potential locus in Xp21.3-22.1 involved in non-specific mental retardation, but also a better definition of the genomic critical region corresponding to this locus.     

"Born from the flank"--discussion concerning "cesarean section" in animals in the Talmud

We determined growth hormone (GH) and insulin-like growth factor I (IGF-I) levels after a 3 h infusion of escalating doses of growth hormone-releasing hormone (GHRH(1-29)) followed by a bolus injection in hypopituitary patients with marked differences in pituitary features at magnetic resonance imaging (MRI) in order to evaluate further the contribution of MRI in the definition of pituitary GH reserve in GH-deficient patients. Twenty-nine patients (mean age 14.5 +/- 4.0 years) were studied. Group I comprised 13 patients: seven with isolated GH deficiency (IGHD) (group Ia) and six with multiple pituitary hormone deficiency (MPHD) (group Ib) who had anterior pituitary hypoplasia, unidentified pituitary stalk and ectopic posterior pituitary at MRI, Group II consisted of eight patients with IGHD and small anterior pituitary/empty sella, while in group III eight had IGHD and normal morphology of the pituitary gland. Growth hormone and IGF-I levels were measured during saline infusion at 08.30-09.00 h, as well as after infusion of GHRH (1-29) at escalating doses for 3h: 0.2 micrograms/kg at 09.00-10.00 h, 0.4 micrograms/kg at 10.00-11.00 h, 0.6 micrograms/kg at 11.00-12.00 h and an intravenous bolus of 2 micrograms/ kg at 12.00 h. In the group I patients, the peak GH response to GHRH(1-29) was delayed (135-180 min) and extremely low (median 2mU/l). In group II it was delayed (135-180 min), high (median 34.8 mU/l) and persistent (median 37.4 mU/l at 185-210 min). In group III the peak response was high (median 30.8 mU/l) and relatively early (75-120 min) but it declined rapidly (median 14.4 mU/l at 185-210 min). In one group I patient, GH response increased to 34.6 mU/l. The mean basal value of IGF-I levels was significantly lower in group I (0.23 +/- 0.05 U/ml) than in groups II (0.39 +/- 0.13U/ ml, p < 0.01) and III (1.54 +/- 0.46 U/ml, p < 0.001) and did not vary significantly during the GHRH(1-29) infusion. The present study demonstrates that the impaired GH response to 3 h of continuous infusion of escalating doses of GHRH(1-29) was strikingly indicative for pituitary stalk abnormality, strengthening the case for use of GHRH in the differential diagnosis of GH deficiency. The low GH response, more severe in MPHD patients, might be dependent on the residual somatotrope cells, while the better response (34.6 mU/l) in the group Ia patients might suggest that prolonged GHRH infusion could help in evaluating the amount of residual GH pituitary tissue. Pituitary GH reserve, given the GH response to GHRH infusion in GH-deficient patients with small anterior pituitary/empty sella, seems to be maintained.     

X-linked mental retardation with a fragile site in Xq and an inversion of chromosome no. 9

The second black male with X-linked mental retardation and a fragile site at Xq27 was ascertained by screening for macroorchidism. GTG banding revealed the presence of an inv(9)(p13q21). This inversion is thought to be a chance occurrence and is probably of no clinical significance. More cases having a marker Xq and a chromosome abnormality are expected; some of these abnormalities will be clinically significant.     

Congenital motor nystagmus linked to Xq26-q27

Congenital motor nystagmus (CMN) is a hereditary disorder characterized by bilateral ocular oscillations that begin in the first 6 mo of life. It must be distinguished from those genetic disorders-such as ocular albinism (OA), congenital stationary night blindness (CSNB), and blue-cone monochromatism (BCM)-in which nystagmus accompanies a clinically apparent defect in the visual sensory system. Although CMN is presumed to arise from a neurological abnormality of fixation, it is not known whether the molecular defect is located in the eye or in the brain. It may be inherited in an autosomal dominant, autosomal recessive, or X-linked pattern. Three families with CMN inherited in an X-linked, irregularly dominant pattern were investigated with linkage and candidate gene analysis. The penetrance among obligate female carriers was 54%. Evaluation of markers in the region of the genes for X-linked OA, CSNB, and BCM revealed no evidence of linkage, supporting the hypothesis that CMN represents a distinct entity. The gene was mapped to chromosome Xq26-q27 with the following markers: GATA172D05 (LOD score 3.164; recombination fraction [theta] = 0.156), DXS1047 (LOD score 10.296; theta = 0), DXS1192 (LOD score 8.174; theta = 0.027), DXS1232 (LOD score 6.015; theta = 0.036), DXS984 (LOD score 6.695; theta = 0), and GATA31E08 (LOD score 4.940; theta = 0.083). Assessment of haplotypes and multipoint linkage analysis, which gave a maximum LOD score of 10.790 with the 1-LOD-unit support interval spanning approximately 7 cM, place the gene in a region between GATA172D05 and DXS1192. Evaluation of candidate genes CDR1 and SOX3 did not reveal mutations in affected male subjects.     

Bilateral periventricular nodular heterotopia with mental retardation and syndactyly in boys: a new X-linked mental retardation syndrome

Bilateral periventricular nodular heterotopia (BPNH) is a recently recognized malformation of neuronal migration, and perhaps proliferation, in which nodular masses of gray matter line the walls of the lateral ventricles. Most affected individuals have epilepsy and normal intelligence with no other congenital anomalies. A striking skew of the sex ratio has been observed because 31 of 38 probands have been female, and one gene associated with BPNH was recently mapped to chromosome Xq28. We report three unrelated boys with a new multiple congenital anomaly-mental retardation syndrome that consists of BPNH, cerebellar hypoplasia, severe mental retardation, epilepsy, and syndactyly. Variable abnormalities included focal or regional cortical dysplasia, cataracts, and hypospadius. We hypothesize that this syndrome involves the same Xq28 locus as isolated BPNH, and we review the expanding number of syndromes associated with BPNH.