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Biomedical subjects

A Schinzel

Publications and source records attributed to A Schinzel.

At least 19 recordsLinked to original sources
PubMed1992

[Molecular genetics diagnosis of Steinert's myotonic dystrophy].

Myotonic dystrophy (DM) is the most common neuromuscular disease with adult onset (incidence 1 in 8000). The biochemical basis of this autosomal dominantly inherited disease is still unknown. The most striking features are myotonia and progressive muscular wasting. There is high variability of disease severity in patients from different families, but also within the same family. For practical reasons three subtypes can be defined: The classical adult onset form of the disease, a mild form with late onset and/or very moderate symptoms, eg. cataracts only, and the most severe congenital form which is transmitted by affected females. Furthermore, the progression of DM in affected families may exhibit an increase in the severity of the disease in successive generations. This observation is called anticipation. Very recently the DM gene has been cloned and an unstable DNA sequence specific for the disease has been characterized. Detection of an enlarged DNA fragment due to the expansion of a trinucleotide (CTG) repeat within the DM gene can be used for direct DNA diagnosis in affected individuals and persons at risk. Furthermore, there is a strong correlation between the length of fragment expansion and the degree of disease severity in gene carriers. We report here our preliminary results of the investigation of over 70 patients and demonstrate the clinical usefulness of this new method by the findings in three families.

Adult↗
PubMed1992

Molecular study of 45,X conceptuses: correlation with clinical findings.

The parental origin of the single X in 45 cases (40 liveborns and 5 fetuses) with a 45,X karyotype was studied using polymorphic DNA probes. The single X was paternal in origin (Xp) in 10 cases (22.2%) and maternal (Xm) in 35 cases (77.8%). Y chromosome material was detected in 1 out of the 35 cases with a 45,Xm constitution. Analysis of parental ages and clinical data of the patients with respect to the origin of the single X revealed no significant differences between the origins.

Fetus↗
PubMed1992

Clinical and ERG data in a family with autosomal dominant RP and Pro-347-Arg mutation in the rhodopsin gene.

In a family with autosomal dominant retinitis pigmentosa, documented over six generations, a previously undescribed point mutation in the rhodopsin gene could be identified. The mutation found in the six affected members examined but in none of the controls, including healthy members of the family, was a point mutation in codon 347 predicting a substitution of the amino acid arginine for proline, designated Pro-347-Arg. Six affected members from two generations were examined clinically and with ganzfeld rod and cone electroretinography. The cone and, more dramatically, the rod electroretinograms were reduced to residual b-wave amplitudes or were non-detectable as early as ages 18 to 22 years. The Pro-347-Arg mutation resulted in a subjectively and clinically homogeneous phenotype: early onset of night blindness before age 11, relatively preserved usable visual fields until about age 30, blindness at ages 40 to 60, and change from an initial apparently sine pigmento to a hyperpigmented and atrophic fundus picture between 30 and 50 years of age.

Adolescent↗
PubMed1992

The genes for the highly homologous Ca(2+)-binding proteins oncomodulin and parvalbumin are not linked in the human genome.

The chromosomal loci of the human parvalbumin and oncomodulin single-copy genes that encode structurally and evolutionarily closely related Ca(2+)-binding proteins were determined by somatic cell hybrid analysis. Southern blot analysis of genomic DNA from 25 human-hamster somatic cell hybrids showed that the human gene for oncomodulin resides on chromosome 7. Analysis of human-mouse hybrids selectively retaining human chromosome 7 or a portion of it allowed specific assignment of the gene locus to the p11-p13 region of chromosome 7 known to be mutated or deleted in patients with the Greig cephalopolysyndactyly syndrome. By gene dosage analysis on Southern blots, we showed that the gene for human parvalbumin maps distally to the cat eye syndrome marker D22S9 on chromosome 22q. Using somatic cell hybrids containing parts of human chromosome 22, the parvalbumin gene was sublocalized to the region 22q12-q13.1. This region contains a linkage group that maps to mouse chromosome 15, region E, and includes the SIS, ARSA, and DIA 1 genes. Our findings are consistent with the recent localization of the mouse parvalbumin gene to this region by two independent methods (C. H. Zühlke et al., 1989, Genet. Res. 54:37-43; S. Adolph et al., 1989, Cytogenet. Cell Genet. 52:177-179).

Animals↗
PubMed1992

Linkage of Rieger syndrome to the region of the epidermal growth factor gene on chromosome 4.

Rieger syndrome is an autosomal dominant disorder of morphogenesis in which previous cytogenetic arrangements have suggested chromosome 4 as a candidate chromosome. Using a group of highly polymorphic short tandem repeat polymorphisms (STRP), including a new tetranucleotide repeat for epidermal growth factor (EGF), significant linkage of Rieger syndrome to 4q markers has been identified. Tight linkage to EGF supports its role as a candidate gene, although a recombinant in an unaffected individual has been identified. This study demonstrates the utility of using polymorphic STRP markers when only a limited number of small families are available for study.

Abnormalities, Multiple↗
PubMed1992

Small nuclear ribonucleoprotein polypeptide N (SNRPN), an expressed gene in the Prader-Willi syndrome critical region.

Prader-Willi syndrome (PWS) is associated with paternally derived chromosomal deletions in region 15q11-13 or with maternal disomy for chromosome 15. Therefore, loss of the expressed paternal alleles of maternally imprinted genes must be responsible for the PWS phenotype. We have mapped the gene encoding the small nuclear RNA associated polypeptide SmN (SNRPN) to human chromosome 15q12 and a processed pseudogene SNRPNP1 to chromosome region 6pter-p21. Furthermore, SNRPN was mapped to the minimal deletion interval that is critical for PWS. The fact that the mouse Snrpn gene is maternally imprinted in brain suggests that loss of the paternally derived SNRPN allele may be involved in the PWS phenotype.

Autoantigens↗
PubMed1992

The acrocallosal syndrome and Greig syndrome are not allelic disorders.

Acrocallosal syndrome is an autosomal recessive form of polysyndactyly associated with mental retardation and agenesis of the corpus callosum. There have been suggestions that it is allelic to the Greig cephalopolysyndactyly syndrome. Linkage analysis, using flanking markers, shows this suggestion is unlikely to be correct.

Abnormalities, Multiple↗
PubMed1992

Uniparental origin of sex chromosome polysomies.

The parental origin of the additional sex chromosomes in 8 cases with high-order sex chromosome polysomies was determined using DNA polymorphisms. The additional sex chromosomes were paternally derived in 3 48,XXYY cases, and maternal in origin in 1 48,XXXY case and 4 49,XXXXY cases. Thus, all extra chromosomes, within a particular patient, were always derived from only one parent. Their most likely origin was successive nondisjunction at the first and second meiotic division in one germ cell. The mechanism involved remains unclear, but appears to be independent of parental ages.

Humans↗
PubMed1992

Confirmation and refinement of the genetic localization of the Coffin-Lowry syndrome locus in Xp22.1-p22.2.

The Coffin-Lowry syndrome (CLS) is an X-linked inherited disease of unknown pathogenesis characterized by severe mental retardation, typical facial and digital anomalies, and progressive skeletal deformations. Our previous linkage analysis, based on four pedigrees with the disease, suggested a localization for the CLS locus in Xp22.1-p22.2, with the most likely position between the marker loci DXS41 and DXS43. We have now extended the study to 16 families by using seven RFLP marker loci spanning the Xp22.1-p22.2 region. Linkage has been established with five markers from this part of the X chromosome: DXS274 (lod score [Z] (theta) = 3.53 at theta = .08), DXS43 (Z(theta) = 3.16 at theta = .08), DXS197 (Z(theta) = 3.03 at theta = .05), DXS41 (Z(theta) = 2.89 at theta = .08), and DXS207 (Z(theta) = 2.73 at theta = .13). A multipoint linkage analysis further placed, with a maximum multipoint Z of 7.30, the mutation-causing CLS within a 7-cM interval defined by the cluster of tightly linked markers (DXS207-DXS43-DXS197) on the distal side and by DXS274 on the proximal side. Thus, these further linkage data confirm and refine the map location for the gene responsible for CLS in Xp22.1-p22.2. As no linkage heterogeneity was detected, this validates the use of the Xp22.1-p22.2 markers for carrier detection and prenatal diagnosis in CLS families.

Abnormalities, Multiple↗
PubMed1992

Expression of the fragile-X in the "premutated"/"non-imprinted" state.

Data about the expression of the fragile site at Xq27.3 from 74 daughters of normal transmitting males (NTMs) were collected from 7 different genetic centers. The majority (85.1%) of these obligate female carriers did not show any cytogenetic expression of fra-X. The remaining 14.9% of these females had frequencies below 3%. In cases with a frequency below 3% of fra-X, a "premutated"/"non imprinted" state of a female carrier should be considered. The results of this collaborative study are in accordance with data from DNA studies taking the premutation model into account.

Female↗
PubMed1991

[Anal sphincter dysplasia as cause of chronic defecation disorders: a clinical and genetic study].

Anal sphincter dysplasia is a congenital, often familial malformation of the anal canal. In the literature, the anomaly is poorly represented and usually referred to as anteriorly or ventrally displaced anus. The range of symptoms includes chronic constipation, severe straining at defecation, encopresis and chronic paradoxical diarrhea with fecal incontinence. One usually finds dysplasia and absent (type I) or incomplete (type II) fixation of the sphincter complex to the coccyx. Both are demonstrable by computerized tomography (CT) as well as by intraoperative dissection of the sphincter muscles. There ist also shortening of the ectodermal segment of the anal canal which is obviously responsible for the disturbed stool sensation. Posterior butterfly anoplasty combined with fixation of the sphincter complex to the coccyx usually leads to immediate improvement of defecation disorders. A genetic study on 42 patients (age 1-52 years) operated on for anal sphincter dysplasia revealed autosomal dominant inheritance with variable expression and probably incomplete penetrance of the mutated gene.

Adolescent↗
PubMed1991

A new mutation in the proteolipid protein (PLP) gene in a German family with Pelizaeus-Merzbacher disease.

A C-to-T transition in exon 4 of the PLP gene was found in 2 affected males and two obligate carriers in a German family with Pelizaeus-Merzbacher disease. The mutation, which causes loss of an HphI site and changes amino acid 155 from threonine to isoleucine, was absent from 108 normal chromosomes. There are 5 concordances and 1 discrepancy between these results and those obtained by magnetic resonance imaging in this family.

Diffuse Cerebral Sclerosis of Schilder↗
PubMed1991

A case of Hirschsprung disease with a chromosome 13 microdeletion, del(13)(q32.3q33.2): potential mapping of one disease locus.

A mentally retarded boy with discrete physical findings, Hirschsprung disease (HD) and a microdeletion of 13q,del(13)(q32.3q33.2) is described. Band 13q33.1 was consistently missing in all cells. There have been, to date, 4 published cases of deletions involving the long arm of chromosome 13 associated with HD: the interstitial deletion reported here is much smaller than, and it partially overlaps with, the previously reported deletions; it could be helpful for mapping one of the genes involved in this disease.

Adolescent↗
PubMed1991

A 48,XXY,+21 Down syndrome patient with additional paternal X and maternal 21.

The origin of meiotic nondisjunction of the extra chromosomes X and 21 was studied in a patient with the karyotype 48,XXY,+21 using DNA polymorphisms. The extra chromosome X was the result of paternal first meiotic nondisjunction of X and Y. The extra chromosome 21 was derived from the mother. The meiotic error in the mother most probably occurred in meiosis II. Thus, this is a combination caused by the chance occurrence of two independent events.

Aneuploidy↗
PubMed1991

The cardio-facio-cutaneous syndrome: report of a patient and review of the literature.

We report a 3-year-old girl with the cardio-facio-cutaneous (CFC) syndrome. She presented the typical combination of mild developmental delay, postnatal onset short stature with relative macrocephaly, a wide and prominent forehead with posteriorly rotated ears and down-slanting palpebral fissures, an atrial septal defect, and ectodermal abnormalities. All cases reported to date occurred sporadically. The aetiology remains unknown; de novo mutations of an autosomal dominant gene seem the most likely explanation.

Abnormalities, Multiple↗
PubMed1991

Pro-347-Arg mutation of the rhodopsin gene in autosomal dominant retinitis pigmentosa.

It has been shown recently that autosomal dominant retinitis pigmentosa may be caused by point mutations of the rhodopsin gene in a portion of families. In this communication, a large six-generation family with autosomal dominant RP is described. Molecular analysis by PCR amplification followed by restriction digestion or heteroduplex analysis suggested a point mutation in codon 347, in which two different mutations (Pro-347-Ser and Pro-347-Leu) have already been reported. Direct sequencing of the patients' DNA revealed a previously undescribed CCG----CGG transversion in codon 347 predicting a Pro----Arg substitution. Ophthalmological data of the patients are summarized and compared to those of patients with other mutations in the rhodopsin gene.

Base Sequence↗
PubMed1991

Unknown syndrome: ischiadic hypoplasia, renal dysfunction, immunodeficiency, and a pattern of minor congenital anomalies.

We report a 6 year old male with a pattern of malformations and anomalies including intrauterine growth retardation, microcephaly, psychomotor retardation, a pattern of craniofacial anomalies (flat face, hypertelorism, epicanthic folds, strabismus, short nose, low set ears), hypospadias and cryptorchidism, bilateral partial cutaneous syndactyly between fingers 2 to 5 and toes 2 to 4, postaxial polydactyly of the fingers and toes, severe conductive hearing loss, hypoplasia of the ischiadic bones, complex renal dysfunction, hypogammaglobulinaemia with proneness to bacterial infections of the upper and lower respiratory tract, and recurrent pseudomembranous enterocolitis. The parents are cousins of Turkish origin.

Abnormalities, Multiple↗