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PubMed2025

A novel insertion/deletion in APC promotor 1B is associated with both gastric and colon polyposis.

Pathogenic variants in the APC gene are classically associated with autosomal dominant familial adenomatous polyposis (FAP), characterized by tens-to-thousands of colonic adenomatous polyps and a high-penetrance predisposition to colorectal cancer. More recently, specific PVs in the YY1 binding motif of APC promoter 1B have been associated with autosomal dominant gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), characterized by tens-to-thousands of fundic gland polyps and a predisposition to gastric cancer but which are only rarely associated with features consistent with FAP. Although management guidelines currently treat FAP and GAPPS as mutually exclusive conditions, the extent of phenotypic overlap is not well-characterized. Here, we present a multi-clinic and -laboratory collaboration reporting a previously undescribed APC promoter 1B insertion/deletion likely pathogenic variant in a family with mixed GAPPS and FAP phenotype. The family proband is a female of unspecified white ancestry. She was diagnosed with GAPPS at age 30 and, after developing gastric cancer at age 39, underwent curative gastrectomy. She is now 61 with a cumulative history of between 50 and 100 colon adenomas and recently completed subtotal colectomy. Her multi-gene panel testing in 2022 demonstrated a likely pathogenic insertion/deletion (indel) within the APC promoter 1B YY1 binding motif (APC c.-192_-191delATinsTAGCAAGGG). Review of a four-generation pedigree revealed the ages of gastric cancer presentation in the family ranged from 39-60's, with advanced gastric polyposis and prophylactic gastrectomy as early as ages 11 and 13 in the proband's daughter and nephew, respectively. Six of 10 (60%) family members known or presumed to carry the APC likely pathogenic variant underwent colectomy or hemicolectomy due to colon polyposis. The youngest known carrier in the family is a 12-year-old female, and the oldest living carrier is the proband's brother, age 66. A novel APC indel causes concomitant GAPPS and FAP presentations in this previously unreported large kindred. Mixed gastric and colon phenotypes have been rarely described in GAPPS families and the ages of presentation of gastric polyposis are strikingly young in the current family with prophylactic gastrectomies completed as early as age 11 and 13. These ages are significantly younger than the 15 years of age at which national guidelines currently recommend initiation of EGD for screening in GAPPS. Although the mechanism for this combined GAPPS-FAP phenotype is unclear, patients in this family and those with similar APC promoter 1B variants should be offered both gastric and colon cancer risk management.

Adult↗
PubMed2002

Paroxysmal kinesigenic dyskinesia and generalized seizures: clinical and genetic analysis in a Spanish pedigree.

Familial paroxysmal kinesigenic dyskinesia (PKD) is a rare disorder featuring brief, dystonic or choreoathetotic attacks, typically triggered by sudden movements. Symptoms usually start in mid-childhood, although in several pedigrees infantile convulsions have been reported as the presenting sign. Previous linkage studies have identified two PKD loci on 16 p12.1-q21. We report here the clinical features of a Spanish kindred with autosomal dominant PKD, in which haplotype data are compatible with linkage to the pericentromeric region of chromosome 16 and exclude linkage to the locus for Paroxysmal Non Kinesigenic Dyskinesia (PNKD) on chromosome 2 q35. In this family, the conservative candidate region for the disease lies between markers D16S3145 and GATA140E03 on 16 p12.1-q21 and partially overlaps with both the Paroxysmal Kinesigenic Dyskinesia - Infantile Convulsions (PKD-IC) critical interval and the Episodic Kinesigenic Dyskinesia 2 (EKD2) locus. Unusual findings in our pedigree were early infantile onset of the dyskinesias in one patient and generalized seizures as adults in two, adding to previous observations of phenotypic overlap between epileptic and non-epileptic paroxysmal disorders. Further clinical and genetic studies are needed to elucidate whether PKD and PKD-IC are allelic disorders with age-dependent phenotypic expression.

Adolescent↗
PubMed1999

The fibrillins.

Fibrillins 1 and 2 are the main constituents of the extracellular microfibrils responsible for the biomechanical properties of most tissues and organs. They are cysteine-rich glycoproteins predominantly made of multiple repeats homologous to the calcium-binding epidermal growth factor module, and are translated as precursor proteins cleaved by furine/PACE-like activities. Fibrillins polymerize extracellularly as parallel bundles of head-to-tail monomers. Binding to calcium rigidifies the structure of the monomers and the supramolecular organization of the macroaggregates. Fibrillin-1 mutations result in the pleiotropic manifestations of Marfan syndrome, and fibrillin-2 alterations cause the overlapping phenotype of congenital contractural arachnodactyly. It is hypothesized that fibrillin-2 guides elastogenesis, whereas fibrillin-1 provides force-bearing structural support. Gene targeting work in the mouse is shedding new light on their distinct and overlapping contributions to tissue morphogenesis and homeostasis. It is also providing an animal model in which to test therapies aimed at reducing hemodynamic stress and the collapse of the aortic matrix during dissecting aneurysm.

Animals↗
PubMed1977

Are the acrocephalosyndactyly syndromes variable expressions of a single gene defect?

Acrocephalosyndactyl (ACS) describes a group of diseases with craniofacial anomalies resulting from premature sutural craniosynostosis and hand and foot anomalies consisting principally of brachydactyly, syndactyly, and polydacytly. Although considerable phenotypic overlap exists, these syndromes are considered by most investigators to be the result of different (although possibly allelic) genes. This report describes the clinical and roentgenologic manifestations in a family wit acrocephalosyndactyly (ACS) showing considerably variation in phenotype. Two different types of ACS were clinically identified in this single family. The proband presented with the classic stigmata of Pfeiffer syndrome while her cousin was considered to be a typical case of Apert syndrome. Further family study revealed that, in addition to these two individuals, seven other family members also have unusually shaped heads and have the facial appearance remiscent of Crouzon disease. Hand and foot anomalies were seen clinically in some but not all of these individuals. From the observations made in this family and from previous reports in the literature, we feel that there is a substantial reason to reevaluate the ACS classification and to consider that the Apert and Pfeiffer types of ACS may be one and the same.

Acrocephalosyndactylia↗
PubMed2004

Re-investigation of the concordance of human NAT2 phenotypes and genotypes.

A comparative study of N-acetyltransferase 2 (NAT2) genotyping and phenotyping (caffeine test method) was performed on 211 persons to elucidate apparent discrepancies in the assignment of NAT2*12 and NAT2*13 alleles which occur in the literature. The study used the standard procedures of genotyping (two PCR runs and application of seven restriction enzymes) and phenotyping (determination of the two caffeine metabolites 5-acetylamino-6-formylamino-3-methyluracil (AFMU) and 1-methylxanthine (1X)), as documented in detail and validated by the Deutsche Forschungsgemeinschaft. The data were consistent with an AFMU/1X molar ratio of 0.85 as cut-off point (antimode) between phenotypically slow and rapid acetylators. Under this provision, several R/S allele combinations did not comply, either fully or partly, with their associated phenotypes. In particular, there was a wide phenotypic overlap of the alleged rapid allele combination groups (i) NAT2*12A/*5A; NAT2*12C/*5D; NAT2*4/*5B, (ii) NAT2*13/*6B; NAT2*4/*6A, and (iii) NAT2*13/*7A; NAT2*4/*7B. These groups obviously contained both phenotypically rapid and slow acetylators. If one assumes that the presence of one "wild type" allele NAT2*4 defines a rapid acetylator the assignment of the alleles NAT2*12A, NAT2*12C, and NAT*13 as determinants of a rapid acetylator phenotype must be questioned. This refers in particular to the nucleotide changes A803G (NAT2*12A, NAT2*12C) and C282T (NAT2*13). Based on discussions in the literature and the data presented here, there is accumulating evidence that current assignments of the NAT2*12 and NAT2*13 alleles as determinants of a rapid acetylator state should be reconsidered.

Acetylation↗
PubMed1997

Relationship between human genotype and phenotype of N-acetyltransferase (NAT2) as estimated by discriminant analysis and multiple linear regression: 1. Genotype and N-acetylation in vivo.

Twenty-six healthy Caucasian subjects were evaluated for polymorphic N-acetyltransferase (NAT2) metabolic activity in vivo by sulfamethazine phenotyping and for their respective NAT2 genotype. Application of discriminant analysis allowed the separation of the rapid and slow acetylators solely on the base of their respective mutation pattern with identical results as achieved by the classical method of discrimination according to the phenotyping results. Multiple linear regression analysis was used to obtain a quantitative relationship between allelic pattern and the phenotypic outcome. It is shown that the computation methods produce relationships enabling the influence of particular mutations and/or allelic configurations on the metabolic activity in vivo to be estimated. This may be important in cases of discordant or overlapping phenotype and genotype results as well as in investigating the NAT2 polymorphism as a risk factor for cancer and other disease in epidemiological studies.

Acetylation↗
PubMed1997

Familial aplasia/hypoplasia of pelvis, femur, fibula, and ulna with abnormal digits in an inbred Pakistani Muslim family: a possible new autosomal recessive disorder with overlapping manifestations of the syndromes of Fuhrmann, Al-Awadi, and Raas-Rothschild.

We describe four affected children belonging to a large, highly inbred Muslim family originating from the North West Frontier Province of Pakistan. All children have a similar pattern of skeletal abnormalities, including aplasia/hypoplasia of the ulnae, hypoplasia of the pelvis, aplasia/hypoplasia of the femora, fibular aplasia, and variable digital abnormalities and absent/dysplastic nails. The phenotype overlaps with the syndromes of Fuhrmann, Al-Awadi, and Raas-Rothschild. The present and previously reported families probably share the same geographic and racial origin, indicating a common genetic basis of the reported skeletal abnormalities in these limb-pelvis aplasia and hypoplasia syndromes. A possibility of a new autosomal recessive syndrome in the present family cannot be excluded. Further delineation and molecular studies are required to clarify the genetic cause and phenotypic variation in Fuhrmann, Al-Awadi, and Raas-Rothschild syndromes.

Abnormalities, Multiple↗
PubMed1991

Marshall syndrome.

We report on a mother and daughter with Marshall syndrome, with the Robin sequence present in the daughter. Results of our efforts to link this syndrome to a defect in type II collagen are reported. We compare and contrast Marshall syndrome with the Stickler syndrome, and propose that enough phenotypic overlap exists to suggest that they are probably allelic expressions of the same locus.

Abnormalities, Multiple↗
PubMed1998

Genotype phenotype correlation in achondroplasia and hypochondroplasia.

Recent studies of the fibroblast growth factor receptor 3 (FGFR3) gene have established that achondroplasia and hypochondroplasia are allelic disorders of different mutations. To determine whether the genotype could be distinguished on the basis of the phenotype, we analysed height, arm span, and skeletal radiographs from 23 patients with achondroplasia and the G380R mutation of FGFR3 and eight with hypochondroplasia and the N540K mutation. Both conditions share the classical pathological features of micromelic short stature, reduced or unchanged interpedicular distances in the lumbar spine, disproportionately long fibulae, and squared and shortened pelvic ilia. These were significantly more severe in the G380R patients than in the N540K patients. Our findings have shown a firm statistical correlation between the genotype and the phenotype, although there were a few exceptional cases in which there was phenotypic overlap between the two conditions.

Achondroplasia↗
PubMed2000

Targeted mutations of transforming growth factor-beta genes reveal important roles in mouse development and adult homeostasis.

Transforming growth factors-beta (TGF-beta) are multifunctional molecules with profound biological effects in many developmental processes including regulation of cell proliferation, differentiation, cell adhesion, skeletal development, haematopoiesis, inflammatory responses, and wound healing. To learn about the role of TGF-beta in vivo, phenotypes of targeted mutations of molecules within the TGF-beta signalling pathway, TGF-beta1, -beta2, -beta3, TGF-beta receptor (TbetaR-II) and the signalling molecules SMAD2, SMAD3 and SMAD4, are discussed in this review. The three individual TGF-beta mutants show distinct and only partially overlapping phenotypes. In mice, targeted disruption of the TGF-beta1 gene results in diffuse and lethal inflammation about 3 weeks after birth, suggesting a prominent role of TGF-beta in the regulation of immune cell proliferation and extravasation into tissues. However, just half of the TGF-beta1 (-/-) conceptuses actually reach partuition due to defective haematopoiesis and endothelial differentiation. Targeted disruption of both TGF-beta2 and TGF-beta3 genes results in perinatal lethality. TGF-beta2 null mice exhibit a broad range of developmental defects, including cardiac, lung, craniofacial, limb, eye, ear and urogenital defects, whereas TGF-beta3 gene ablation results exclusively in defective palatogenesis and delayed pulmonary development. The TbetaR-II null phenotype closely resembles that of TGF-beta1 (-/-) conceptuses, which die in utero by E10.5. Loss of SMAD2 or SMAD4 results in related phenotypes: the mutants fail to form an organized egg cylinder, lack mesoderm required for gastrulation and die prior to E8.5. Together, gene ablation within the TGF-beta signalling pathway supports the notion of a prominent role of TGF-beta during development.

Animals↗
PubMed2003

Identification of MeCP2 mutations in a series of females with autistic disorder.

Rett disorder and autistic disorder are both pervasive developmental disorders. Recent studies indicate that at least 80% of Rett Disorder cases are caused by mutations in the methyl-CpG-binding protein 2 (MeCP2) gene. Since there is some phenotypic overlap between autistic disorder and Rett disorder, we analyzed 69 females clinically diagnosed with autistic disorder for the presence of mutations in the MeCP2 gene. Two autistic disorder females were found to have de novo mutations in the MeCP2 gene. These data provide additional evidence of variable expression in the Rett disorder phenotype and suggest MeCP2 testing may be warranted for females presenting with autistic disorder.

Adolescent↗
PubMed2001

[Long QT syndrome and Brugada syndrome: 2 aspects of the same disease?].

In clinical cardiology, resort has recently been made to molecular genetics in order to explain some mechanisms that underlie sudden cardiac death in young people with structurally normal hearts. It has become evident that genetic mutations regarding cardiac ion channels may disrupt the delicate balance of currents in the action potential, thus inducing malignant ventricular tachyarrhythmias. The cardiac sodium channel gene, SCN5A, is involved in two of such arrhythmogenic diseases, the Brugada syndrome and one form of the long QT syndrome (LQT3). It is believed that these syndromes result from opposite molecular effects: Brugada syndrome mutations cause a reduced sodium current, while LQT3 mutations are associated with a gain of function. The effects of class I antiarrhythmic drugs have been used to differentiate these diseases. Intravenous flecainide is used as a highly specific test to unmask the electrocardiographic phenotype of the Brugada syndrome. On the other hand, on the basis of experimental and clinical studies, the possibility that the same drugs act as a gene-specific therapy in this disorder by contrasting the effect of mutations in LQT3 has been explored. Recent evidence shows that phenotypic overlap may exist between the Brugada syndrome and LQT3. One large family with a SCN5A mutation and a "mixed" electrocardiographic pattern (prolonged QT interval and ST-segment elevation) has been reported. Moreover, our recent data showed that flecainide challenge may elicit ST-segment elevation in some LQT3 patients. The presence of "intermediate" phenotypes highlights a remarkable heterogeneity suggesting that clinical features may depend upon the single mutation. Only deepened understanding of the genotype-phenotype correlation will allow the definition of the individual patient's risk and the development of guidelines for clinical management.

Anti-Arrhythmia Agents↗
PubMed2001

Epileptic phenotypes associated with mitochondrial disorders.

OBJECTIVE: To define the clinical and EEG features of the epileptic syndromes occurring in adult and infantile mitochondrial encephalopathies (ME). METHODS: Thirty-one patients with recurrent and apparently unprovoked seizures associated with primary ME were included in the study. Diagnosis of ME was based on the recognition of a morphologic, biochemical, or molecular defect. RESULTS: Epileptic seizures were the first recognized symptom in 53% of the patients. Many adults (43%) and most infants (70%) had nontypical ME phenotypes. Partial seizures, mainly with elementary motor symptoms, and focal or multifocal EEG epileptiform activities characterized the epileptic presentation in 71% of the patients. Generalized myoclonic seizures were an early and consistent symptom only in the five patients with an A8344G mitochondrial DNA point mutation with classic myoclonus epilepsy with ragged red fibers (MERRF) syndrome or "overlapping" characteristics. Photoparoxysmal EEG responses were observed not only in patients with typical MERRF, but also in adult patients with ME with lactic acidosis and strokelike episodes (MELAS), or overlapping phenotypes, and in one child with Leigh syndrome. CONCLUSIONS: Epilepsy is an important sign in the early presentation of ME and may be the most apparent neurologic sign of nontypical ME, often leading to the diagnostic workup. Except for those with an A8344G mitochondrial DNA point mutation, most of our patients had partial seizures or EEG signs indicating a focal origin.

Adolescent↗
PubMed1995

Clinical overlap of Beckwith-Wiedemann, Perlman and Simpson-Golabi-Behmel syndromes: a diagnostic pitfall.

We report on a child who died in the neonatal period. Major external anomalies included foetal overgrowth, macroglossia, and ambiguous genitalia (micropenis and perineoscrotal hypospadias with cryptorchidism). Necropsy showed a large right diaphragmatic hernia, visceromegaly, multicystic kidney dysplasia, Langerhans islet hyperplasia, nephroblastomatosis, multiple adrenal adenomas, and dysplastic testicles. The child illustrates the difficulties of the differential diagnosis of overgrowth syndromes in the neonatal period, and the phenotypic overlap of Beckwith-Wiedemann, Denys-Drash, Simpson-Golabi-Behmel, Perlman and possibly Meacham-Winn syndromes. Simpson-Golabi-Behmel syndrome was felt to be the most likely diagnosis. If this opinion is correct, genital ambiguity, hydramnios and nephroblastomatosis should be added to the clinical spectrum of Simpson-Golabi-Behmel syndrome. Differential diagnosis between the above-mentioned syndromes is of major importance for accurate genetic counseling, considering the differences in recurrence risk. The present case underlines the need for long-term survey of patients suspected of having Simpson-Golabi-Behmel syndrome, who could be at risk for embryonic tumours.

Abnormalities, Multiple↗
PubMed2006

A variable combination of features of Noonan syndrome and neurofibromatosis type I are caused by mutations in the NF1 gene.

Signs of neurofibromatosis type 1 (NF1) and Noonan syndrome (NS), two distinct autosomal dominant disorders, occur together in patients reported as Watson syndrome (WS), neurofibromatosis-Noonan syndrome (NFNS), partial LEOPARD syndrome, NS with features of NF1, and NF1 with Noonan-like features. The molecular basis of these combined phenotypes was poorly understood and controversially discussed over several decades. Only recently, there is increasing evidence for WS and NFNS being allelic to NF1 in the majority of patients. In this study we describe seven novel patients from five unrelated families with variable phenotypes of the NF1-NS spectrum which were systematically analyzed for mutations in the disease-causing genes NF1 for NF1 and PTPN11 for NS. Heterozygous mutations or deletions of NF1 were identified in all patients, while no PTPN11 mutation was found. The NF1 mutation segregated with the phenotype in both familial cases. These results support the hypothesis that variable phenotypes of the NF1-NS spectrum represent variants of NF1 in the majority of cases. Constitutive deregulation of the Ras pathway either through activating mutations of PTPN11 or through haploinsufficiency of neurofibromin, which acts as a Ras-inactivating GTP-ase, is probably the common pathogenetic mechanism explaining the phenotypic overlap of NS and NF1.

Adult↗
PubMed2006

Phenotypic spectrum associated with mutations of the mitochondrial polymerase gamma gene.

Mutations in the gene coding for the catalytic subunit of the mitochondrial DNA (mtDNA) polymerase gamma (POLG1) have recently been described in patients with diverse clinical presentations, revealing a complex relationship between genotype and phenotype in patients and their families. POLG1 was sequenced in patients from different European diagnostic and research centres to define the phenotypic spectrum and advance understanding of the recurrence risks. Mutations were identified in 38 cases, with the majority being sporadic compound heterozygotes. Eighty-nine DNA sequence changes were identified, including 2 predicted to alter a splice site, 1 predicted to cause a premature stop codon and 13 predicted to cause novel amino acid substitutions. The majority of children had a mutation in the linker region, often 1399G-->A (A467T), and a mutation affecting the polymerase domain. Others had mutations throughout the gene, and 11 had 3 or more substitutions. The clinical presentation ranged from the neonatal period to late adult life, with an overlapping phenotypic spectrum from severe encephalopathy and liver failure to late-onset external ophthalmoplegia, ataxia, myopathy and isolated muscle pain or epilepsy. There was a strong gender bias in children, with evidence of an environmental interaction with sodium valproate. POLG1 mutations cause an overlapping clinical spectrum of disease with both dominant and recessive modes of inheritance. 1399G-->A (A467T) is common in children, but complete POLG1 sequencing is required to identify multiple mutations that can have complex implications for genetic counselling.

Adolescent↗
PubMed2002

Genetic analysis of patients with the Saethre-Chotzen phenotype.

Saethre-Chotzen syndrome is a common craniosynostosis syndrome characterized by craniofacial and limb anomalies. Intragenic mutations of the TWIST gene within 7p21 have been identified as a cause of this disorder. There is phenotypic overlap with other craniosynostosis syndromes, and intragenic mutations in FGFR2 (fibroblast growth factor receptor 2) and FGFR3 (fibroblast growth factor receptor 3) have been demonstrated in the other conditions. Furthermore, complete gene deletions of TWIST have also been found in a significant proportion of patients with Saethre-Chotzen syndrome. We investigated 11 patients clinically identified as having the Saethre-Chotzen phenotype and 4 patients with craniosynostosis but without a clear diagnosis. Of the patients with the Saethre-Chotzen phenotype, four were found to carry the FGFR3 P250R mutation, three were found to be heterozygous for three different novel mutations in the coding region of TWIST, and two were found to have a deletion of one copy of the entire TWIST gene. Developmental delay was a distinguishing feature of the patients with deletions, compared to patients with intragenic mutations of TWIST, in agreement with the results of Johnson et al. [1998: Am J Hum Genet 63:1282-1293]. No mutations were found for the four patients with craniosynostosis without a clear diagnosis. Therefore, 9 of our 11 patients (82%) with the Saethre-Chotzen phenotype had detectable genetic changes in FGFR3 or TWIST. We propose that initial screening for the FGFR3 P250R mutation, followed by sequencing of TWIST and then fluorescence in situ hybridization (FISH) for deletion detection of TWIST, is sufficient to detect mutations in > 80% of patients with the Saethre-Chotzen phenotype.

Acrocephalosyndactylia↗
PubMed2005

How genetics research in Parkinson's disease is enhancing understanding of the common idiopathic forms of the disease.

PURPOSE OF REVIEW: Rapid progress in genetics has meant that there are now five genes identified for 'Parkinson's disease'. The detailed phenotypes vary, but generally the dominant genes cause a Lewy body disease spectrum whereas recessive genes cause a milder parkinsonism with variable inclusion body pathology. The subject of this review is to highlight these discoveries and to discuss their relationships to idiopathic Parkinson's disease. RECENT FINDINGS: In January 2004, mutations in PINK1, coding for a mitochondrial kinase, were found to be causal for recessive parkinsonism. Subsequently, several studies have found additional mutations associated with early onset parkinsonism. Some cases have been described with a phenotype much closer to idiopathic Parkinson's disease, but it does not appear that PINK1 is a major risk factor for the sporadic disease. Later in the same year, the LRRK2 gene was shown to cause a dominant disease with a broader phenotype. The protein product was named dardarin and contains GTPase and kinase domains. Lewy bodies have been reported in LRRK2 cases, potentially linking this gene with sporadic Parkinson's disease. One mutation, G2019S, is found in a significant percentage of cases, including sporadic Parkinson's disease. SUMMARY: Mutations in these two genes, along with previously described Mendelian variants, are beginning to yield important information about loss of specific neuronal groups or to protein inclusion pathology. How this relates to sporadic Parkinson's disease, however, is not yet fully defined. There are clear phenotypic overlaps with genetic and sporadic Parkinson's disease, especially for the dominant genes, suggesting that common facets of pathogenesis may exist.

Humans↗