Identification of the familial cylindromatosis tumour-suppressor gene.

Familial cylindromatosis is an autosomal dominant genetic predisposition to multiple tumours of the skin appendages. The susceptibility gene (CYLD) has previously been localized to chromosome 16q and has the genetic attributes of a tumour-suppressor gene (recessive oncogene). Here we have identified CYLD by detecting germline mutations in 21 cylindromatosis families and somatic mutations in 1 sporadic and 5 familial cylindromas. All mutations predict truncation or absence of the encoded protein. CYLD encodes three cytoskeletal-associated-protein-glycine-conserved (CAP-GLY) domains, which are found in proteins that coordinate the attachment of organelles to microtubules. CYLD also has sequence homology to the catalytic domain of ubiquitin carboxy-terminal hydrolases (UCH).

Minor physical anomalies in autism: a meta-analysis.

Autism is a complex neurodevelopmental disorder in which the interactions of genetic, epigenetic and environmental influences play a causal role. Despite the compelling evidence for a strong heritability, the etiology and molecular mechanisms underlying autism remain unclear. High phenotypic variability and genetic heterogeneity confounds the identification of susceptibility genes. The lack of robust indicators to tackle this complexity in autism has led researchers to seek for novel diagnostic tools to create homogenous subgroups. Several studies have indicated that patients with autism have higher rates of minor physical anomalies (MPAs) and that MPAs may serve as a diagnostic tool; however, the results have been inconsistent. Using the cumulative data from seven studies on MPAs in autism, this meta-analysis seeks to examine whether the aggregate data provide evidence of a large mean effect size and statistical significance for MPAs in autism. It covers the studies using multiple research methods till June 2007. The current results from seven studies suggested a significant association of MPAs in autism with a robust pooled effect size (d=0.84), and thereby provide the strongest evidence to date about the close association between MPAs and autism. Our results emphasize the importance of MPAs in the identification of heterogeneity in autism and suggest that the success of future autism genetics research will be exploited by the use of MPAs. Implications for the design of future studies on MPAs in autism are discussed and suggestions for further investigation of these important markers are proposed. Clarifying this relation might improve understanding of risk factors and molecular mechanisms in autism.

Copy number changes of the microcephalin 1 gene (MCPH1) in patients with autism spectrum disorders.

Autism spectrum disorder (ASD) represents a set of neurodevelopmental disorders with a strong genetic aetiology. Chromosomal rearrangements have been detected in 5-10% of the patients with ASD, and recent applications of array comparative genomic hybridisation (aCGH) are identifying further candidate regions and genes. In this study, we present four patients who implicate microcephalin 1 (MCPH1) in band 8p23.1 as an ASD susceptibility gene. Patient 1 was a girl with a syndromic form of autistic disorder satisfying the Autism Diagnostic Interview-Revised (ADI-R), Autism Diagnostic Observation Schedule (ADOS) and Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria. Oligonucleotide aCGH (oaCGH) showed that she had a classic inv dup del(8)(qter-> p23.1::p23.1-> p21.2) containing at least three candidate genes; MCPH1 and DLGAP2 within the 6.9-Mb terminal deletion and NEF3 within the concomitant 14.1-Mb duplication. Three further patients with MCPH1 copy number changes were found using single-nucleotide polymorphism (SNP) array analysis in a cohort of 54 families with ASD patients. Our results show that ASD can be a component of the classical inv dup del(8) phenotype and identify changes in copy number of MCPH1 as a susceptibility factor for ASD in the distal short arm of chromosome 8.

The phenotypic spectrum in patients with arginine to cysteine mutations in the COL2A1 gene.

BACKGROUND: The majority of COL2A1 missense mutations are substitutions of obligatory glycine residues in the triple helical domain. Only a few non-glycine missense mutations have been reported and among these, the arginine to cysteine substitutions predominate. OBJECTIVE: To investigate in more detail the phenotype resulting from arginine to cysteine mutations in the COL2A1 gene. METHODS: The clinical and radiographic phenotype of all patients in whom an arginine to cysteine mutation in the COL2A1 gene was identified in our laboratory, was studied and correlated with the abnormal genotype. The COL2A1 genotyping involved DHPLC analysis with subsequent sequencing of the abnormal fragments. RESULTS: Six different mutations (R75C, R365C, R519C, R704C, R789C, R1076C) were found in 11 unrelated probands. Each mutation resulted in a rather constant and site-specific phenotype, but a perinatally lethal disorder was never observed. Spondyloarthropathy with normal stature and no ocular involvement were features of patients with the R75C, R519C, or R1076C mutation. Short third and/or fourth toes was a distinguishing feature of the R75C mutation and brachydactyly with enlarged finger joints a key feature of the R1076C substitution. Stickler dysplasia with brachydactyly was observed in patients with the R704C mutation. The R365C and R789C mutations resulted in classic Stickler dysplasia and spondyloepiphyseal dysplasia congenita (SEDC), respectively. CONCLUSIONS: Arginine to cysteine mutations are rather infrequent COL2A1 mutations which cause a spectrum of phenotypes including classic SEDC and Stickler dysplasia, but also some unusual entities that have not yet been recognised and described as type II collagenopathies.

Oculodentodigital dysplasia with mandibular retrognathism and absence of syndactyly: a case report with a novel mutation in the connexin 43 gene.

Oculodentodigital dysplasia (ODDD) is a rare, autosomal dominant pleiotropic disorder, caused by mutations in the Connexin 43 (Cx43 or GJA1) gene. Described here is the case of a 10-year-old girl with enamel hypoplasia, typical facies and mental delay, initially thought to be related to an unknown metabolic disorder. Careful clinical re-evaluation revealed a type of ODDD, characterised by the predominance of facial and ophthalmological involvement with mandibular retrognathism, and by the absence of cutaneous hand or foot syndactyly. A novel single-sequence variation (Nt460A>G) in exon 2, resulting in the substitution of alanine for threonine at amino acid 154, was found. These findings confirm once again the highly variable phenotypic expression caused by Cx43 mutations.

Virilization of the external genitalia and severe mental retardation in a girl with an unbalanced translocation 1;18.

A female infant with dysmorphic facial features, psychomotor retardation, and clitoris hypertrophy is described. Molecular cytogenetic analyses revealed a de novo unbalanced translocation, causing partial monosomy 1p36 and partial trisomy 18q22. Monosomy 1p was confirmed by FISH, and trisomy of the distal part of chromosome 18q was demonstrated by microFISH. Gene copy number changes in these chromosomal regions were determined by array-CGH. The absence of a number of facial dysmorphic signs, and the presence of clitoris hypertrophy indicate that the combination of a del(1p36->pter) with a dup(18q22->qter) may lead to a unique phenotypic constellation. The findings at birth and at age 12 years in our patient are compared with genotype-phenotype correlations discussed in the literature.

[Congenital myotonic dystrophy--the significance of a handshake]. / Congenitale myotone dystrofie--wat is er 'aan de hand'?

Three neonates, all girls, were presented immediately after birth with severe hypotonia. Two of them needed artificial ventilation because of respiratory insufficiency. All three pregnancies had been complicated by reduced fetal movements and moderate cerebral ventricular dilatation and in two of the three there was also polyhydramnios and congenital talipes. In all three infants congenital myotonic dystrophy was suspected after diagnosing myotonia in the mother. This was done by observing that none of the mothers were unable to release their grip immediately on command after shaking hands. Ophthalmological examination of the women revealed polychromatic lens crystals characteristic of myotonic dystrophy. Congenital myotonic dystrophy was confirmed by DNA analysis, as well as myotonic dystrophy in the mothers. All had an expansion of the number of cytosine-thymine-guanine(CTG)-trinucleotides in a part of the myotonic dystrophy protein-kinase gene. The first two infants died after 2 days and 15 months respectively.

Characterization of some glycolytic enzymes from human retina and retinoblastoma.

GLycolytic enzymes were studied from normal human retinas (both fetal and adult) and from retinoblastomas of eight patients and an established retinoblastoma cell line. No significant differences were found between the enzyme activities in the tissues investigated except for hexokinase and pyruvate kinase, which were significantly decreased in the tumor cells. In fetal retina, five different forms of pyruvate kinase could be detected by electrophoresis (K4, K3M, K2M2, KM3, and M4). In adult retina the K4 isozyme is almost absent, while in retinoblastoma the M4 isozyme is hardly present. In the retinoblastoma cell line, the M4 isozyme is completely absent. Alanine inhibition of pyruvate kinase from the retinoblastoma cell line is more inhibited compared to the pyruvate kinase of fetal retina and retinoblastoma and is even more inhibited compared to adult retina. Electrophoresis of aldolase from adult retina revealed the presence of all potential A-C hybrids (A4, A3C, A2C2, AC3, and C4). Fetal retina, however, is characterized by the predominance of the A type. The same patterns were observed in the retinoblastoma cell line and retinoblastoma. However, in other brain tumors, e.g., gliomas of adults, a five-membered A-C hybrid set is found. Electrophoresis of hexokinase from normal fetal and adult retina revealed the predominance of hexokinase type I; retinoblastoma and retinoblastoma cell line are both characterized by the presence of considerable amounts of hexokinase type II. The isozyme shifts in retinoblastoma result in an enzyme pattern identical to that of fetal retina except for the presence of hexokinase type II.

Prenatal and early postnatal treatment in 3-phosphoglycerate-dehydrogenase deficiency.

3-phosphoglycerate-dehydrogenase (3-PGDH) deficiency is an L-serine biosynthesis disorder, characterised by congenital microcephaly, severe psychomotor retardation, and intractable seizures. We report prenatal diagnosis of an affected fetus by DNA mutation analysis. Ultrasound assessment showed a reduction in fetal head circumference from the 75th percentile at 20 weeks' gestation to the 29th percentile at 26 weeks. L-serine was then given to the mother, which resulted in an enlarged fetal head circumference to the 76th percentile at 31 weeks. At birth, the girl's head circumference was normal, and at 48 months' follow-up, her psychomotor development has been unremarkable. 3-PGDH deficiency is an inborn metabolic error that can be successfully treated antenatally.

A complex haemoglobinopathy diagnosis in a family with both beta zero- and alpha (zero/+)-thalassaemia homozygosity.

The occurrence of point mutation alpha-thalassaemia and of complex combinations of haemoglobin defects is underestimated. Haemoglobinopathies, the most frequent monogenic recessive autosomal disorder in man, occur predominantly in Mediterranean, African and Asiatic populations. However, countries of immigration with a low incidence in the indigenous population, are now confronted with a highly heterogeneous array of imported defects. Furthermore, the occurrence of severe phenotypes is bound to increase in the near future because of the endogamous growth of the ethnical minorities and the lack of prevention. We describe an Afghan family in which both partners of a consanguineous relationship are carriers of a beta- as well as an alpha-thalassaemia determinant. The combination of defects was revealed by the in vitro measurement of the beta/alpha biosynthetic ratio and was characterised at the DNA level. The molecular defects involved are the Cd5(-CT), a Mediterranean beta zero-thalassaemia mutation, and the alpha 2(zero/+)-thalassaemia AATA(-AA) polyadenylation defect. The alpha-thalassemia defect is a rare RNA-processing mutant described only twice before in heterozygous form in Asian-Indian patients. The mutation suppresses the expression of a alpha 2 gene and reduces the expression of the less efficient, 3' located alpha 1 gene as well, inducing a near alpha zero-thalassaemia phenotype. This defect is now described for the first time in the homozygous condition in one of the children who, in addition to being homozygous for the alpha-thalassaemia point mutation, is also a carrier of the beta zero-thalassaemia defect. A previously described homozygous case of the alpha (zero/+)-thalassaemia condition, caused by a similar polyadenylation defect, was characterised by a severe HbH disease. However, the patient described here present at 7 years of age with severe caries, like his beta-thalassaemia homozygous brother but without hepatosplenomegaly, haemolysis or severe anaemia. The haematological analysis revealed 9.5 g/dl Hb; 5.4 x 10(12)/I RBC; 0.33 I/I PCV; 61 fl MCV; 17.6 pg MCH and 6.2% of HbA2. The biosynthetic ratio beta:alpha was 1.6 and no HbH fraction was detectable either on electrophoresis or as inclusion bodies. The parents reported no complications during pregnancy, at birth, or in the neonatal period in rural Afghanistan. We presume therefore that the counterbalancing effect induced by the co-existing beta-thalassaemia defect could have modified a potentially severe perinatal HbH disease into a strongly hypochromic but well compensated 'alpha zero-like heterozygous' thalassaemia phenotype. The risk of a severe HbH disease, could have been easily missed in this family which was referred because of a child affected with beta-thalassaemia major.

Frequency of glycogen storage disease type II in The Netherlands: implications for diagnosis and genetic counselling.

Glycogen storage disease type II (GSD H) is an autosomal recessive myopathy. Early and late-onset phenotypes are distinguished - infantile, juvenile and adult. Three mutations in the acid alpha-glucosidase gene are common in the Dutch patient population: IVS1(-13T-->G), 525delT and delexon18. 63% of Dutch GSD II patients carry one or two of these mutations, and the genotype-phenotype correlation is known. To determine the frequency of GSD II, we have screened an unselected sample of neonates for the occurrence of these three mutations. Based on the calculated carrier frequencies, the predicted frequency of the disease is 1 in 40000 divided by 1 in 138 000 for infantile GSD II and 1 in 57 000 for adult GSD II. This is about two to four times higher than previously suggested, which is a reason to become more familiar with the presentation of GSD II in its different clinical forms and to adjust the risk assessment for genetic counselling.

Clinical and molecular correlations in spinocerebellar ataxia type 6: a study of 24 Dutch families.

BACKGROUND: Autosomal dominant cerebellar ataxias (ADCAs), or spinocerebellar ataxias (SCAs), are a heterogeneous group of neurodegenerative disorders. Mild CAG repeat expansions in the alpha(1A) voltage-dependent calcium channel gene are associated with SCA type 6 (SCA6). OBJECTIVE: To obtain further insight into the contribution of SCA6 mutations to the phenotypic variability in Dutch patients with ataxia. DESIGN: Survey and case series. SETTING: Hospitalized care, referral center. PATIENTS AND METHODS: The SCA6 locus was analyzed for CAG repeat expansions in a referred sample of 220 Dutch families with progressive cerebellar ataxia. Clinical characteristics of patients with SCA6 were investigated and correlated with molecular findings. RESULTS: The diagnosis SCA6 was confirmed in 24 families comprising 30 familial and 4 sporadic cases. Mean +/- SD age at onset was 50.1 +/- 11.1 years. Expanded CAG repeats with sizes 22, 23, and 25 were found. These sizes correlated inversely with age at onset. No intergenerational changes in CAG repeat size were detected. Despite this, 2 families showed clinical anticipation. CONCLUSIONS: This study provides the first detailed description of Dutch patients with SCA6. Clinical analysis identifies SCA6 as a late-onset ataxia in which eye movement abnormalities are prominent and consistent early manifestations. No single clinical sign can be considered specific for SCA6. Some patients have ataxia combined with episodic headaches or nausea, suggesting an overlap among SCA6, eposidic ataxia type 2, and familial hemiplegic migraine. Spinocerebellar ataxia type 6 accounts for approximately 11% of all Dutch families with ADCA. Analysis of SCA6 contributes further to the genetic classification of patients with ADCA, including patients without a clear family history of the disease.

Phenotypic expression of late-onset glycogen storage disease type II: identification of asymptomatic adults through family studies and review of reported families.

The intrafamilial variability of late-onset glycogen storage disease type II was studied in siblings of 18 patients and in reports in the literature. Siblings of seven of the 18 index cases opted for DNA testing or enzyme studies after being informed by the index case of the availability of testing, and after genetic counselling. Of the 12 siblings tested, five asymptomatic individuals were diagnosed (mean age, 32.8 years; range, 17-53). Intrafamilial variability in the age at onset (more than 10 years difference) or in the clinical symptoms was found in one of seven sibships tested in this study, and also in seven sibships reported in the literature. We advocate that testing should not be offered to healthy siblings of late-onset glycogen storage disease type II patients as a routine, because it is impossible to give a precise prognosis to an individual who is symptom-free, but has been identified with a glycogen storage disease type II genotype, nor is there any therapeutic intervention available.

Additional case of opsismodysplasia supporting autosomal recessive inheritance.

The authors describe clinical and radiological findings in a 2-year-old boy from consanguineous parents. A diagnosis of opsi(s)modysplasia (= delayed maturation) had been made (MIM 258480). The purpose of this paper is to draw attention to the striking radiological manifestations. Consanguinity in the parents of our case and occurrence in a brother and sister in a previous report support an autosomal recessive transmission.

Intermittent hair loss in a child with PIBI(D)S syndrome and trichothiodystrophy with defective DNA repair-xeroderma pigmentosum group D.

We describe a girl with photosensitivity (P), ichthyosis (I), brittle hair (B), impaired intelligence (I), possibly decreased fertility (D), and short stature (S). The clinical findings fit into the PIBI(D)S syndrome and trichothiodystrophy. A remarkable and probably unique observation for this disorder was the intermittent character of the scalp hair loss during infectious periods in this patient. Easy suntanning suggested photosensitivity and prompted DNA repair studies which demonstrated reduced UV-induced DNA repair synthesis. Subsequent studies have assigned this patient to xeroderma pigmentosum group D and suggested a specific deficiency of 6-4 photoproduct repair. An unaffected child was diagnosed in the next pregnancy of the mother.

Cerebral gigantism (Sotos syndrome) in two patients with fra(X) chromosomes.

Two boys were studied who had a large size at birth and/or overgrowth, unusual length, large head circumference and minor anomalies, mainly facial. Their mental development appeared mildly retarded. A clinical diagnosis of cerebral gigantism (Sotos syndrome) was made. However, subsequent chromosome studies (medium 199, with 5% fetal calf serum) showed fra(X) (q27) in 4 and 6% of cells, respectively. These observations give evidence for genetic heterogeneity in cerebral gigantism. Fra(X) studies are recommended in all cases of cerebral gigantism (Sotos syndrome).

Association of distal arthrogryposis, mental retardation, whistling face, and Pierre Robin sequence: evidence for nosologic heterogeneity.

We report on 3 unrelated patients with the heterogeneous fetal hypokinesia sequence. They have distal arthrogryposis, severe developmental retardation, facial anomalies as seen in the Freeman-Sheldon syndrome ("whistling face"), and Pierre Robin sequence. The present cases show a remarkable clinical resemblance to the 3 sibs described by Illum et al. (Illum N, Reske-Nielsen E, Skovby F, Askjaer SA, Bersen A (1988): Neuropediatrics 19:186-192), where calcium deposits were found in the nervous system and skeletal muscle. The presence of severe to profound developmental retardation in the present 3 patients is equally in favour of a central nervous system abnormality as the pathogenetic basis of the fetal hypokinesia sequence with secondary facial changes and distal arthrogryposis.

The diagnostic management of newborns with congenital contractures: a nosologic study of 75 cases.

A prospective clinical study is presented of 75 patients with multiple congenital contractures. With the data from medical history, child neurologic examinations, laboratory tests including chromosome and dermatoglyphic analysis, and neuropathology in 23 cases with perinatal death, a nosological or syndromal diagnosis was made in 61 cases. These cases were classified by localization of causal pathology in the categories "cerebral dysgenesis", spinal cord defects, neuromuscular disorders and miscellaneous disorders without muscle weakness. Following this concept, the various modes of inheritance of specific disorders presenting with congenital contractures, as well as possibilities for prenatal diagnosis by ultrasonography are discussed. A guideline for the child neurologic evaluation of infants with congenital contractures is proposed. It is concluded that: 1) specification of the causal lesion and proper classification of disorders with congenital contractures is crucial for genetic counseling, (prenatal) diagnosis and management; 2) the analysis of dermatoglyphics in differential diagnosis of congenital contractures should be restudied; and 3) more study and experience is required in the observation of abnormal or decreased fetal movements by ultrasonography.

Parents' responses to disclosure of genetic test results of their children.

The psychological reactions of 22 parental couples and 3 single parents were investigated after disclosure of genetic test results of their children. The children were tested for the early-onset, monogenetic cancer disorder multiple endocrine neoplasia type 2. Participants came from 13 different families and were aged between 28 and 47 years. Parents who were informed that their child was a gene carrier reacted with resignation, showed moderate to high levels of test-related and general anxiety, but few psychological complaints. Daily activities were disturbed in 43% of the parents with carrier-children. There was little disruption of the parents' future perspective, apart from some socioeconomic disadvantages and increased parental concern for the carrier-children. Most parents with carrier-children showed restraint with respect to short-term prophylactic treatment. Parents with favorable test results showed significantly less anxiety and no disturbance in their daily activities. They did not, however, seem to be reassured by the DNA test result. These parents questioned the reliability of the DNA test, wanted confirmation of the test results, and were eager to continue screening of their noncarrier children. Parents, especially those with a lower level of education and/or a pessimistic view of the future, were distressed by unfavorable test results. Additional counseling is advised to prevent parents of carrier-children worrying unnecessarily, or parents with children in whom the disease gene was not found being not reassured. Am. J. Med. Genet. 94:316-323, 2000.