Mandibulofacial Dysostosis with Microcephaly: Mutation and Database Update

Mandibulofacial dysostosis with microcephaly (MFDM) is a multiple malformation syndrome comprising microcephaly, craniofacial anomalies, hearing loss, dysmorphic features, and, in some cases, esophageal atresia. Haploinsufficiency of a spliceosomal GTPase, U5-116 kDa/EFTUD2, is responsible. Here, we review the molecular basis of MFDM in the 69 individuals described to date, and report mutations in 38 new individuals, bringing the total number of reported individuals to 107 individuals from 94 kindreds. Pathogenic EFTUD2 variants comprise 76 distinct mutations and seven microdeletions. Among point mutations, missense substitutions are infrequent (14 out of 76; 18%) relative to stop-gain (29 out of 76; 38%), and splicing (33 out of 76; 43%) mutations. Where known, mutation origin was de novo in 48 out of 64 individuals (75%), dominantly inherited in 12 out of 64 (19%), and due to proven germline mosaicism in four out of 64 (6%). Highly penetrant clinical features include, microcephaly, first and second arch craniofacial malformations, and hearing loss; esophageal atresia is present in an estimated ∼27%. Microcephaly is virtually universal in childhood, with some adults exhibiting late "catch-up" growth and normocephaly at maturity. Occasionally reported anomalies, include vestibular and ossicular malformations, reduced mouth opening, atrophy of cerebral white matter, structural brain malformations, and epibulbar dermoid. All reported EFTUD2 mutations can be found in the EFTUD2 mutation database (http://databases.lovd.nl/shared/genes/EFTUD2).

The intellectual disabilities evaluation and advice system (IDEAS): outcome of the first 55 cases

IDEAS (intellectual disabilities evaluation and advice system) provides the opportunity for physicians who are sending samples for the Greenwood Genetic Center (GGC) 92-gene X-linked intellectual disability (XLID) (formerly X-linked mental retardation) panel to have their male patient's clinical features reviewed by an experienced panel of six Clinical Geneticists. They were asked to obtain parental consent, complete a one-page information form, and provide A-P and lateral photographs. The panel members independently reviewed the material and forwarded comments about clinical features, possible diagnoses, and/or further testing for the patient. We present the results of the first 55 patients evaluated. In only a single case did all panelists agree on a non-XLID diagnosis, later proven by genetic testing. The XLID gene panel diagnosed an additional five (9%) cases, but in only two cases did one panelist suggest the correct gene, which was one of four they suggested. This paper examines the possible reasons for the low rate of clinical diagnosis and suggests that, while the data received were often incomplete, the most important reasons for lack of diagnoses were the source of referral and selection of patients for review. We did note that there were a number of instances where we disagreed with the submitted information as to whether the individual was dysmorphic and with the stated presence of certain physical signs, most often downslanted palpebrae and posterior ear angulation. These differences in assessment of clinical signs and the general lack of completeness and detail provided in the standard data sheet, including that regarding the extended family history, lead us to raise concerns regarding the feasibility of establishing high quality central clinical databases designed to aid in the interpretation of exomic/genomic variants.

Considering the Embryopathogenesis of VACTERL Association

The nonrandom co-occurrence of vertebral, anorectal, cardiac, tracheoesophageal, genitourinary, and limb malformations, recognized as the VACTERL association, has not been satisfactorily explained from either a causation or embryopathogenesis standpoint. Few familial cases have been identified and maternal diabetes is the only environmental influence implicated to date. Mutations in single genes have been found in a number of syndromes with one or more of the VACTERL malformations, but these syndromes usually have other features which distinguish them from the VACTERL association. Animal models have provided clues to molecular pathways that may be involved in the embryogenesis of the VACTERL structures. What is lacking is the systematic study of individual genes and pathways in well-composed cohorts of patients, which is now possible with high throughput molecular technologies.

Limb-body wall defect. Is there a defensible hypothesis and can it explain all the associated anomalies?

Aside from gastroschisis and omphalocele, major defects of the ventral body (thoracoabdominal) wall are relatively uncommon and almost universally lethal. They are most often associated with other anomalies including those of the limbs that may range from amelia to mild positional deformations, unusual craniofacial malformations, and a variety of visceral abnormalities that include the heart, lungs, genitourinary system, and gut. This complex of ventral wall anomalies has been discussed under a broad and changing nomenclature that has included amniotic band disruption complex, amnion rupture sequence, limb-body wall defect (or complex), and simply body wall complex. Three major theories have been suggested to explain this complex: early amnion rupture (operating through uterine pressure and/or disruption by amniotic bands), vascular compromise (primarily hypoperfusion), and an early intrinsic defect of the developing embryo. We present four patients that illustrate the spectrum of ventral body wall defects, and from there critique the current hypotheses of pathogenesis. We conclude that this association of malformations originates as early as the embryonic disc stage, and that some of the observed associated anomalies are secondary complications of the primary disturbance in embryogenesis. We propose a new explanation for the atypical facial clefts and cranial malformations that are often observed.

Detailed assessment of the ear in Cornelia de Lange syndrome: comparison with a control sample using the new dysmorphology guidelines

The literature abounds with reports of malformation syndromes in which human external ears are variously described as dysplastic, abnormal, large/small, low set, typical, or in some way unusual. Rarely is the ear well illustrated or described in meaningful detail. With few exceptions, such as Down syndrome, there is no real understanding of the degree to which ear morphology is affected in a specific syndrome. This paper describes a retrospective attempt to apply the recently published Morphological Definitions of the ear to compare a control sample of convenience with a group of patients with Cornelia de Lange syndrome (CdLS) (all six papers in this issue are available online, open access at http://www3.interscience.wiley.com/journal/121641055/issue). Although this study has a number of limitations, it demonstrates that the method can be successfully applied and is capable of producing data that can be subjected to statistical analysis. The ears of the patients with CdLS were significantly different from the controls over a number of descriptors, the most significant of which included more frequent apparent posterior rotation, a shorter more serpiginous antihelical stem and sharper antihelical to inferior crus angle, a shorter crus helix, a more V-shaped incisura, and a smaller lobe.

Oculocerebrocutaneous and encephalocraniocutaneous lipomatosis syndromes: blind men and an elephant or separate syndromes?

The discovery of relevant causative genes has subdued the lumping versus splitting debate with respect to a growing number of syndromes. However, it remains paramount to define unknown genesis syndromes as precisely and appropriately as possible in order to provide accurate prognosis and to facilitate future research. The presentation of a 14-month-old girl, of normal intelligence, who had a colobomatous right eye with cyst, minor intracranial MRI variants, and an area of sparse scalp hair containing a 1 by 1.5 cm, soft, domed, and indented skin lesion suggested a diagnosis of mild oculocerebrocutaneous syndrome (OCCS). An initial exploration of the literature exposed the extreme variability in cases that have been reported as OCCS, and emphasized its possible relationship to encephalocraniocutaneous lipomatosis (ECCL), thus challenging the initial diagnosis. Cases reported, or discussed by others, as possible OCCS (40) and ECCL (44) were reviewed as completely as possible in an effort to determine whether diagnostic criteria could be developed for these syndromes, and to see whether or not evidence favored their continued separation as two syndromes. The approach used was to summarize the data for all cases, to select major and minor diagnostic criteria on the basis of the relative specificity and/or frequency of a sign, to then apply the criteria in a standard fashion and to review the outcome to see if the classification of cases made clinical sense, and to make appropriate adjustments. The criteria were not chosen so as to separate the syndromes and in some instances the same criteria could apply to either syndrome. An approach is outlined for handling reports of patients that purport to be variants or to expand the spectrum of a syndrome, and in the case of OCCS and ECCL this resulted in most such examples being excluded. Application of diagnostic criteria suggests that OCCS and ECCL are distinct, and that some case reports, including some purporting to expand the spectrum of OCCS, should be excluded, at least until such time as the etiology of these conditions is known and those cases can be tested. These diagnostic criteria were developed on the basis of literature reports that varied in their quantity and quality of detail. Furthermore, in many cases reliance had to be placed on copies of original studies with resultant degradation of photographic information. Modern ocular imaging, and histopathology of eye and skin malformations, will often clarify the specific nature of a malformation and, therefore, define exact diagnostic criteria and leave fewer uncertain cases. In the absence of anomalies in those systems, or if histopathology or appropriate imaging is unavailable, the diagnosis in some cases will continue to remain uncertain; this is not an argument for lumping the syndromes.

Is multicenter collaborative research in clinical genetics dead and, if so, what killed it?

This study describes the course of a clinical trial designed to investigate the possible role of thrombophilic factors in limb reduction defects, which was abandoned after 1 year because lack of progress of the project through ethics review and the failure to make significant inroads in patient recruitment. Factors that are thought to have contributed to the failure are discussed, in the hope that others can avoid some of the pitfalls.

A randomized trial comparing alternative approaches to prenatal diagnosis counseling in advanced maternal age patients

Prenatal diagnosis (PND) is offered routinely as part of pregnancy care to a large number of women at increased risk of fetal anomalies. Despite an extraordinary growth in the use of PND and significant resource allocation, few studies have examined outcomes of PND counseling, and virtually no research has evaluated the relative efficacy of various approaches to genetic counseling. This study was a randomized trial that compared which counseling methods - individual, group, and use of a decision aid - are effective in PND counseling for women of advanced maternal age (>/=35 years) and their partners. Three hundred and fifty-two women and 225 partners completed pre- and post-intervention questionnaires assessing changes in knowledge, decisional conflict, state anxiety, satisfaction, use of PND, and pregnancy outcomes. All participants showed a significant increase in knowledge and a decrease in decisional conflict post intervention. Those in the group intervention showed a significantly greater increase in knowledge than those in the individual counseling intervention. While high levels of satisfaction were reported by all, those in individual counseling were significantly more satisfied than those receiving group counseling or the decision aid. This study has shown unique benefits with each type of intervention such that women and their partners preferred individual genetic counseling, while they learned best in group-counseling sessions, and experienced the least decisional conflict regarding genetic testing with a decision aid.

The external ear: More attention to detail may aid syndrome diagnosis and contribute answers to embryological questions

The human pinna has a complex shape and yet the basic components of normal structure are remarkably constant between individuals. It is precocious in its appearance during embryogenesis and it has been subject to many developmental and surgical studies, yet questions remain as to its primary embryogenesis and the causes of its malformations. Unfortunately, the vast majority of clinical reports of syndromes and of individuals with dysmorphic signs provide limited and inadequate description of the external ear. Given the intricate pattern of the pinna, and hence its potential for morphological variation, we think that more attention to the specific description of ear anomalies may lead to a better appreciation of the etiology and embryology of the malformations. Furthermore, in some cases correlation with specific syndromes may provide an aid to diagnosis. Towards those ends this paper reviews some of the controversy concerning the embryology of the pinna, and discusses a number of the better-defined anomalies of the external ear. Although it has been suggested that anomalies of the insertion and orientation of intrinsic muscles of the pinna may be responsible for variations in external ear morphology, we think it likely that in many cases the anomalous insertions may be secondary.

The Hunter-McAlpine syndrome results from duplication 5q35-qter

In 1977 Hunter et al. J Med Genet 1977: 14 (6): 430-437, reported a family with six affected members, connected over three generations through unaffected individuals. Subsequently, several other patients purported to have the condition were reported. The condition became known as the Hunter-McAlpine syndrome, and there was debate as to whether or not it was identical to the Ruvalcaba syndrome or a type of tricho-rhino-phalangeal syndrome. In this article we confirm that the original family and a patient reported by Ades et al. Clin Dysmorphol 1993: 2 (2): 123-130 have cryptic translocations resulting in duplication of 5q35-qter. Similarities are noted between our patients and others in the literature with duplication of this chromosome segment.

Lathosterolosis: an inborn error of human and murine cholesterol synthesis due to lathosterol 5-desaturase deficiency

Lathosterol 5-desaturase catalyzes the conversion of lathosterol to 7-dehydrocholesterol in the next to last step of cholesterol synthesis. Inborn errors of cholesterol synthesis underlie a group of human malformation syndromes including Smith-Lemli-Opitz syndrome, desmosterolosis, CHILD syndrome, CDPX2 and lathosterolosis. We disrupted the lathosterol 5-desaturase gene (Sc5d ) in order to further our understanding of the pathophysiological processes underlying these disorders and to gain insight into the corresponding human disorder. Sc5d (-/-) pups were stillborn, had elevated lathosterol and decreased cholesterol levels, had craniofacial defects including cleft palate and micrognathia, and limb patterning defects. Many of the malformations found in Sc5d (-/-) mice are consistent with impaired hedgehog signaling, and appear to be a result of decreased cholesterol rather than increased lathosterol. A patient initially described as atypical SLOS with mucolipidosis was shown to have lathosterolosis by biochemical and molecular analysis. We identified a homozygous mutation of SC5D (137A>C, Y46S) in this patient. An unique aspect of the lathosterolosis phenotype is the combination of a malformation syndrome with an intracellular storage defect.

A boy with developmental delay, malformations, and evidence of a connective tissue disorder: possibly a new type of cutis laxa

We report a 7.5-year-old boy with loose translucent skin, aortic dilatation, hyperextensible veins, recurrent respiratory problems, pectus excavatum, arthralgias, lax joints, mild epiphyseal dysplasia, and umbilical and inguinal hernias. He also has developmental delay, progressive bilateral sensorineural hearing loss, an unusual facial appearance, terminal digit hypoplasia with unusual radiographic changes in some of the phalanges, glandular hypospadias, shawl scrotum, and undescended testes. Biochemical investigations, including electrophoresis of Types 1 and 3 procollagens and collagens, and quantification of serum copper and ceruloplasmin, are normal. Relative to age-matched control patients the electron micrographs of the boy's dermis show elastin fibers to be decreased in number, and abnormal in appearance, with a low matrix to microfibril ratio. The organ distribution of abnormalities and the nature of the findings suggest a connective tissue disorder. We contrast and compare this boy's phenotype to those of the classic connective tissue disorders. We conclude that he has cutis laxa with features that distinguish him from previously described types of cutis laxa.

A novel mutation in the IHH gene causes brachydactyly type A1: a 95-year-old mystery resolved

Brachydactyly type A1 (BDA1) was the first disorder described in terms of autosomal dominant Mendelian inheritance. Early in the 1900s Farabee and Drinkwater described a number of families with BDA1. Examination of two of Drinkwater's families has revealed that, although they are not known to be related, both share a common mutation within the Indian hedgehog gene ( IHH). This novel mutation is a guanine to adenine transition at nucleotide 298, resulting in an Asn100Asp amino acid substitution. Both families demonstrate significant intrafamilial phenotypic heterogeneity among the affected individuals. Examination of single nucleotide polymorphisms (SNP) has shown that the affected individuals in both families share SNPs within IHH consistent with that of a common founder. The identification of the same mutation in these families has answered a question that is nearly a century old about the genetic cause of their disease and supports the hypothesis that IHH plays a pivotal role in normal human skeletogenesis.

Osteofibrous dysplasia: two affected male sibs and an unrelated girl with bilateral involvement

Osteofibrous dysplasia (OFD) is a tumor-like bone lesion that occurs most often in the tibia, presenting as a painless swelling or anterior bowing. Radiographs show a well-circumscribed intracortical lucency, or multiple lucencies separated by sclerotic borders, associated with a diaphyseal expansion. The histogenesis of OFD and its possible relationships to fibrous dysplasia and to adamantinoma have been the subject of significant discussion and investigation. We have been unable to find any reports of familial OFD, and have found only two references to bilateral involvement. In this article, we report both bilateral and familial involvement, and suggest that more thorough investigation of patients and their families may uncover similar cases, and perhaps support a genetic component to the etiology of this condition.

Coffin-Lowry syndrome: a 20-year follow-up and review of long-term outcomes

The Coffin-Lowry syndrome has become well established since the first report of affected patients by Coffin et al. [1966: Am J Dis Child 112:205-213]. Since that time over a hundred cases have been reported and the responsible gene has been identified. However, there remains a paucity of long-term follow-up information on older patients with which to counsel affected families about prognosis. There is also much to be learned about genotype-phenotype correlations. In 1982 we reported 12 patients (including carrier mothers) from eight families, one of whom had died about the time the paper was written. Recently, we have been able to obtain follow-up information on six of the affected patients and one of the carrier mothers. A number of important complications have occurred, including premature death, loss of ambulation, and quadriplegia. This paper updates the medical histories of our patients and summarizes the clinically important complications that have been reported in patients with Coffin-Lowry syndrome. There are few data on patients over the age of 30, and much more longer term follow-up is required.

Medical genetics: 2. The diagnostic approach to the child with dysmorphic signs

Dysmorphology is the branch of clinical genetics in which clinicians and researchers study and attempt to interpret the patterns of human growth and structural defects. Reaching an accurate diagnosis for children with dysmorphic signs is important to their families, because it makes available all the accumulated knowledge about the relevant condition and may provide the family with the opportunity for interaction with patient or parent support groups. I show in this review that reaching a diagnosis in dysmorphology involves an approach that is not fundamentally different from that of other medical disciplines. Cytogenetic and molecular techniques continue to improve our ability to make precise syndrome diagnoses; however, these tests are expensive and should be used selectively.

Participation rates of Ashkenazi Jews in a colon cancer community-based screening/prevention study

In a recent colon cancer risk study, genetic assessment and colonoscopy were offered to virtually all of the adult Ashkenazi Jews in an urban community. The present study was designed to examine factors influencing participation and response in the initial study and to suggest strategies for improving participation in future health promotion programs. The study comprised a random sample of three groups of individuals who had been targeted for participation in the previous study: those who had (a) agreed to participate (n = 234); (b) declined participation (n = 179); and (c) failed to respond to a mailed recruitment package (n = 128). All participants completed a brief telephone survey. Key multivariate predictors of both response and participation were individuals' perceptions of the drawbacks of participating in colon cancer screening research and the degree of decisional conflict they experienced. Response was further predicted by the influence of spouses, family history of colon cancer, past knowledge of genetic testing for colon cancer, and education level. Participation was predicted by awareness that the study was supported by the Ashkenazi Jewish community, past experience with genetic testing, individuals' perceptions of the benefits of participating, and whether or not they had children. The degree to which individuals understand the purpose and nature of genetic screening research, along with their levels of decisional conflict and other psychosocial factors, may influence the likelihood of their participation in such research. Results of this study suggest a number of possible strategies for improving participation and response rates in disease prevention and detection studies.