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Autosomal recessive form of whistling face syndrome in sibs.

Two sibs with the whistling face syndrome, born to unaffected parents, are presented. They had the full facial and limb manifestations typical of this disorder, for which there is evidence of autosomal dominant inheritance. The existence of an autosomal recessive form of this syndrome has been suspected previously on the basis of a limited number of observations. Our study substantiates genetic heterogeneity of this condition and suggests that the autosomal recessive form could be even less rare than is generally considered.

Abnormalities, Multiple↗

Autosomal recessive Melnick-Needles syndrome or ter Haar syndrome? Report of a patient and reappraisal of an earlier report.

We report on a patient with congenital glaucoma, brachycephaly with flat occiput, large anterior fontanel, hypertelorism, anteverted nostrils, thoracolumbar kyphosis, prominent coccyx with skin fold, short hands and feet, flexion deformity of fingers, and clubfeet. He had a double-outlet right ventricle with ventricular septal defect, and severe tricuspid insufficiency. Mild skeletal changes included short tubular bones, absence of distal phalanges of toes, caliber variation of ribs, and scalloping of the anterior surface of vertebrae. The patient died at age 21 months. He belongs to the same extended family as 3 similarly affected patients, previously described by ter Haar et al. [1982: Am J Med Genet 13:469-477] as representing an autosomal recessive form of Melnick-Needles syndrome. We believe this diagnosis is no longer tenable. After having reviewed the relevant literature, we conclude that most probably we are dealing with a new autosomal recessive syndrome. We propose to name this entity ter Haar syndrome.

Diagnosis, Differential↗

Genetic mapping of a novel X-linked recessive colobomatous microphthalmia.

Colobomatous microphthalmia is a common ocular malformation with a heterogeneous phenotype. The majority of cases without associated systemic abnormalities have an autosomal dominant inheritance pattern [McKusick, 1990: Mendelian inheritance in man]. A few isolated cases with autosomal recessive transmission have been described [Zlotogora et al., 1994: Am J Med Genet 49:261--262]. To our knowledge, no cases of X-linked colobomatous microphthalmia that are not a part of a syndrome or a multisystem disorder have been reported. In this study, we describe a genetic and clinical evaluation of a large pedigree in which colobomatous microphthalmia is segregating in an X-linked recessive fashion. Based on recombination breakpoint analysis, we have determined that the critical interval exists between markers DXS989 and DXS441, placing the disease locus on the proximal short arm or the proximal long arm of the X chromosome. Using linkage analysis, we obtained two-point lod scores of 2.71 at zero recombination with markers DXS1058, DXS6810, DXS1199, and DXS7132. Overlapping multipoint analysis established a broad maximum from marker DXS1068 to marker DXS7132, a region spanning approximately 28 cM. This study provides evidence for the presence of a new locus for colobomatous microphthalmia.

Adolescent↗

Severity of X-linked recessive bulbospinal neuronopathy correlates with size of the tandem CAG repeat in androgen receptor gene.

The genetic mutation of X-linked recessive bulbospinal neuronopathy is amplification of a polymorphic tandem CAG repeat in the androgen receptor gene. We studied this CAG repeat in 26 Japanese patients from 21 families with X-linked recessive bulbospinal neuronopathy. The number of CAG repeats was significantly correlated with the age at onset of limb muscular weakness (r = -0.596, p < 0.001) and age-adjusted scored disability (r = 0.446, p < 0.03). The length of the CAG repeat therefore seems to be a determinant factor of clinical severity.

Adult↗

Estimation of the frequency of occult mutations for an autosomal recessive disease in the presence of genetic heterogeneity: application to genetic hearing loss disorders.

The routine testing for pathologic mutation(s) in a patient's DNA has become the foundation of modern molecular genetic diagnosis. It is especially valuable when the phenotype shows genetic heterogeneity, and its importance will grow as treatments become genotype specific. However, the technology of mutation detection is imperfect and mutations are often missed. This can be especially troublesome when dealing with a recessive disorder where the combination of genetic heterogeneity and missed mutation creates an imprecision in the genotypic assessment of individuals who do not appear to have the expected complement of two pathologic mutations. This article describes a statistical approach to the estimation of the likelihood of a genetic diagnosis under these conditions. In addition to providing a means of testing for missed mutations, it also provides a method of estimating and testing for the presence of genetic heterogeneity in the absence of linkage data. Gene frequencies as well as estimates of sensitivity and specificity can be obtained as well. The test is applied to GJB2 recessive nonsyndromic deafness, Usher syndrome types Ib and IIa, and Pendred-enlarged vestibular aqueduct syndrome.

Connexin 26↗

Four novel TMC1 (DFNB7/DFNB11) mutations in Turkish patients with congenital autosomal recessive nonsyndromic hearing loss.

Mutations in the transmembrane channel-like gene 1 (TMC1) cause prelingual autosomal recessive (DFNB7/11) and postlingual progressive autosomal dominant (DFNA36) nonsyndromic hearing loss. To determine the genetic causes of autosomal recessive nonsyndromic hearing loss (ARNSHL) in the northeast and east of Turkey, 65 unrelated families without mutations in the protein coding region of the GJB2 (GJB2-negative) were analyzed. A genomewide scan for homozygosity and linkage analysis in one of these families revealed a 13.2 cM critical region between D9S273 and D9S153 at chromosome 9p13.2-q21.31 with a maximum two-point lod score of 4.00 at theta=0.0 for marker D9S175. TMC1 is in this critical region. Homozygosity screening with intragenic markers for TMC1 in the remaining 64 families suggested involvement of this gene in three additional families. Subsequent sequencing of TMC1 in these four families revealed four novel homozygous mutations, c.776A>G [p.Tyr259Cys], c.821C>T [p.Pro274Leu], c.1334G>A [p.Arg445His], and c.1083_1087delCAGAT [p.Arg362ProfrX6]. Our results indicate that TMC1 mutations account for at least 6% (4/65) of ARNSHL in GJB2-negative Turkish families from the northeast and east of Turkey.

Amino Acid Sequence↗

Mutation analysis of the parkin gene in Russian families with autosomal recessive juvenile parkinsonism.

Autosomal recessive juvenile parkinsonism (AR-JP) is a form of hereditary parkinsonism characterized by variable clinical presentations and caused by mutations in a novel gene, parkin, on chromosome 6q25.2-27. Until now, no Russian cases of parkin-associated AR-JP have been reported on. We recruited 16 patients from 11 Russian families with dopa-responsive movement disorders according to the following criteria: 1) family history compatible with autosomal recessive inheritance; 2) onset of symptoms at </=30 years of age; and 3) the lack of mutations in the GTP cyclohydrolase I gene (in sporadic cases). Mutation screening of the parkin gene was carried out by a semiquantitative PCR assay and direct sequencing of the coding region. Six different parkin mutations (both deletions and point mutations) were identified in the index cases from four families, including a novel point mutation in the donor splice site (IVS1+1G-->A). The majority of our parkin-associated cases were characterized by early-onset dopa-responsive parkinsonism with benign course and slow progression (5 patients from two families have been followed for as long as 18-36 years), and 1 patient had a phenotype of dopa-responsive dystonia. This first description of Russian patients with AR-JP and molecularly proven parkin mutations confirms the widespread occurrence of this polymorphic hereditary extrapyramidal disorder.

Adult↗

Recessed elliptical-centric view-ordering for contrast-enhanced 3D MR angiography of the carotid arteries.

Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the acquisition to the bolus transit to maximize arterial signal and minimize venous artifacts. The rising edge of the bolus is not utilized in conventional elliptical-centric view-ordering because the critical k-space center must be acquired with full arterial enhancement. In this study, a recessed elliptical-centric view-ordering scheme is introduced in which the k-space center is acquired a few seconds following scan initiation. The recessed view-ordering is shown to be more robust to timing errors than the conventional scheme in a study of 37 patients.

Carotid Artery Diseases↗

Altered Na+ channel activity and reduced Cl- conductance cause hyperexcitability in recessive generalized myotonia (Becker).

Intact muscle fibers or resealed fiber segments from 7 patients with recessive generalized myotonia were studied in vitro. All fibers had normal resting membrane potentials and normal resting [Ca2+]i several hours after removal. Contractions were characterized by slowed relaxation which was due to electrical after-activity. Often spontaneous depolarizations were recorded intracellularly. In all fibers, the steady state voltage-current relationship was abnormal, due to a reduced Cl- conductance. However, this conductance ranged from 0% to 66% of the total membrane conductance, whereas, in normal muscle, it was 80%. Theoretically, myotonic after-discharges would not appear until the Cl- conductance is below 20%. Thus, the membrane hyperexcitability must be due to another defect, at least in the preparations in which the Cl- conductance was only slightly reduced. In all patches from all patients investigated with the patch clamp technique, we observed reopenings of the Na+ channels throughout depolarizing pulses (such behavior was absent in normal muscle). If a patch was polarized to potentials less negative than the resting potential, the duration of the reopenings increased. We conclude that a combination of reduced Cl- conductance and the reopenings of Na+ channels underlie the electrical after-activity in recessive generalized myotonia.

Chlorides↗

Non-invasive first trimester fetal gender assignment in pregnancies at risk for X-linked recessive diseases.

OBJECTIVES: Prenatal diagnosis in families affected by X-linked recessive disorders should ideally be limited to the subjects at increased risk, i.e. male fetuses, in order to avoid the risk of fetal loss due to the invasive procedure in healthy female fetuses. The aim of the study was to assess the fetal sex within the first trimester of gestation by two non-invasive approaches, using ultrasonography and a molecular analysis of fetal DNA extracted from whole maternal blood with specific markers, in order to avoid invasive sampling in female fetuses. METHODS: A total number of 18 fetuses at risk for an X-linked recessive disease were included in the present investigation. Maternal peripheral blood was analysed between 7 and 12 weeks of gestation by nested PCR for the detection of fetal DNA and the prediction of fetal gender. In addition, when the biparietal diameter (BPD) was between 21 and 23 mm, an ultrasonographic examination was carried out to assess the fetal gender. CVS was then performed in male fetuses only. RESULTS: Fetal gender was correctly assigned by ultrasonography between 21 and 23 mm of BPD in all the cases studied, whereas DNA extracted from whole maternal blood accurately predicted the gender in all the female cases (10), but failed in 4 out of 8 male fetuses, erroneously assigned as females. CONCLUSION: The present study shows that sonography is able to accurately predict the fetal gender within the first trimester of pregnancy, whereas the molecular analysis of DNA extracted from whole maternal blood is biased by false-Y-negative results in 50% of the cases.

Chorionic Villi Sampling↗

Correction of steroid sulfatase deficiency by gene transfer into basal cells of tissue-cultured epidermis from patients with recessive X-linked ichthyosis.

To develop an experimental model for somatic gene therapy we have tried to correct the steroid sulfatase (STS) deficiency in tissue-cultured primary epidermal keratinocytes from patients suffering from recessive X-linked ichthyosis. An efficient Epstein-Barr virus-based vector was constructed, in which full-length steroid sulfatase cDNA is located between an SV40 early promotor and processing signals. After STS gene transfer into cultured basal cells from ichthyotic skin, the cells produce large amounts of enzymatically active steroid sulfatase protein. The subpopulation of transfected cells can be made to produce approximately 100 times more STS activity than normal keratinocytes. Keratinocytes from patients suffering from recessive X-linked ichthyosis display an abnormal phenotype when developing a multilayered tissue in culture: Initially an extensive burst of keratinization is observed, followed by rapid, premature shedding and degradation of most suprabasal cell layers, leaving a culture with hyperproliferative relatively immature keratinocytes. Transfection of these immature ichthyotic cells with the functional STS construct led to an increase in the amount of retained cell material in the culture medium, indicating an increased cell maturation. It is possible to genetically label individual transfected epidermal cells with a reporter gene. Cotransfection experiments with STS and reporter gene vectors show that the cohort of transfected cells had a tendency to develop less rapidly since they became overrepresented in the smaller size classes at the same time the total population was somewhat shifted toward higher cell sizes. We interpret these results as an indication that restoration of the enzymatic activity induces a more normal maturation of the transfected keratinocytes.

Arylsulfatases↗

Pinealocytes contacting the cerebrospinal fluid of the suprapineal recess in the Mongolian gerbil (Meriones unguiculatus).

The pineal system of the Mongolian gerbil (Meriones unguiculatus) was investigated by light and electron microscopy, special attention being paid to the sites of contact with the ventricular system. The results reveal that the pineal system of this species has a specific topographical relationship to the suprapineal recess of the third ventricle. The dorsal side of the proximal part of the pineal system forms the floor and the caudal wall of this recess. Here, a consistent and relatively large area lacks an ependymal lining, enabling pinealocytes to come into direct contact with the cerebrospinal fluid (CSF). This area is assumed to be the morphological correlate of a close functional interrelationship between the pineal tissue and the CSF.

Animals↗

Cerebrospinal fluid-contacting area in the pineal recess of the vole (Microtus agrestis), guinea pig (Cavia cobaya), and rhesus monkey (Macaca mulatta).

The ventricular lining in the pineal recess of the vole (Microtus agrestis), guinea pig (Cavia cobaya) and Rhesus monkey (Macaca mulatta) was investigated light and electron microscopically. Deep in the pineal recess of all three species the ependymal lining exhibits interruptions. A varying proportion of pinealocytes penetrates through this ependymal area, so that the surface of the protruding cells is directly exposed to the cerebrospinal fluid (CSF). At their base, these cells are anchored in the hypependymal tissue by means of processes. It is conjectured that these pinealocytes are engaged in secreting pineal substances into the CSF, as various physiological findings appear to indicate.

Animals↗

A liquor contacting area in the pineal recess of the golden hamster (Mesocricetus auratus).

The wall of the third ventricle in the pineal recess of the golden hamster (Mesocricetus auratus) has been investigated by light and electron microscopy. Deep in the pineal recess, where the ependymal lining is thin and non-ciliated, clusters of pinealocytes protrude into the ventricular lumen. They force the ependyma apart so that their surface is directly exposed to the CSF, while basal processes extend towards the hypependymal pineal tissue. It is assumed that these cells may secrete melatonin into the CSF which is known to contain varying amounts of this hormone.

Animals↗

Anterior chamber angle recession in uveal melanomas.

Sixteen uveal melanomas in celloidin sections and eight other fresh cases of melanoma were examined using different clinical and histological methods. A recession of the lateral border of the anterior chamber angle was found in most of them. The grade of this distortion varied from very deep to insignificant, but was apparent in most cases. Seven fresh cases were gonioscopically examined and some recession was seen in five of them.

Anterior Chamber↗

Sequence analysis of the human hTg737 gene and its polymorphic sites in patients with autosomal recessive polycystic kidney disease.

DNA sequence analysis of the human Tg737 gene was performed in 36 patients with the autosomal recessive form of polycystic kidney disease (ARPKD). Coding exons and their adjacent splice sites were screened for mutations. Pathogenic exon or splice region mutations were not identified although one exonic and two intronic polymorphic sites were discovered. These results are in agreement with another study that has recently reported linkage to Chromosome (Chr) 6p21-cen in a set of 16 ARPKD families. STS mapping has localized the gene to a YAC contig that includes D13S175 on chromosome 13q12.1. The polymorphisms found in the htG737 gene will permit its future evaluation as a candidate gene for other recessive cystic renal diseases and as a modifier gene in human PKD.

Base Sequence↗

Clinical spectrum of steroid sulfatase deficiency: X-linked recessive ichthyosis, birth complications and cryptorchidism.

When boys affected with steroid sulfatase deficiency are delivered, the lack of the enzyme in the placenta may cause birth complications. In postnatal life this gene defect gives rise to X-linked recessive ichthyosis. In a series of 25 patients birth complications were reported in 9 cases. Of these boys, 4 displayed bilateral inguinal cryptorchidism and one was affected unilaterally. In a further boy we observed unilateral inguinal cryptorchidism without a history of birth complications. In one patient who had been delivered by forceps, abdominal bilateral cryptorchidism resulted in severe hypogenitalism. A review of the literature revealed 30 cases with X-linked recessive ichthyosis displaying hypogenitalism or cryptorchidism or both. In conclusion, cryptorchidism should be considered as a further clinical manifestation of steroid sulfatase deficiency.

Adolescent↗

Ultrasonographic evaluation of the anterior recess in the normal hip: a prospective study on 166 asymptomatic children.

PURPOSE: To redefine the ultrasonographic features of the normal hip joint in children and to establish a normal value for the neck-capsule distance (NCD) of its anterior recess. MATERIALS AND METHODS: 332 hips of 166 asymptomatic children were examined sonographically. In a sagittal section plane the maximum distance between the anterior surface of the femoral neck and the anterior limit of the articular capsule (NCD-A) was measured. RESULTS: The hypoechoic synovial membrane occupying the anterior recess could always be differentiated from the capsule. An additional thin layer of synovial fluid was detected in 12% of probands. The configuration of the capsule varied with different rotation positions of the legs. In small children the mean NCD-A increased from 2.5 mm at 65 cm height to 5 mm at 100 cm height. In larger children the mean NCD-A was 5.5 mm. The mean right-to-left difference was 0.5 mm with a pathological limit of 2 mm. CONCLUSIONS: The pathological limit of the NCD-A increases from 3.5 to 7.5 mm in relation to the height. Sonographic investigation of the pediatric hip joint must include detailed demonstration of anatomical structures to avoid misinterpretations.

Adolescent↗