Personal journeys to and in human genetics and dysmorphology.

Genetics has become a critical component of medicine over the past five to six decades. Alongside genetics, a relatively new discipline, dysmorphology, has also begun to play an important role in providing critically important diagnoses to individuals and families. Both have become indispensable to unraveling rare diseases. Almost every medical specialty relies on individuals experienced in these specialties to provide diagnoses for patients who present themselves to other doctors. Additionally, both specialties have become reliant on molecular geneticists to identify genes associated with human disorders. Many of the medical geneticists, dysmorphologists, and molecular geneticists traveled a circuitous route before arriving at the position they occupied. The purpose of collecting the memoirs contained in this article was to convey to the reader that many of the individuals who contributed to the advancement of genetics and dysmorphology since the late 1960s/early 1970s traveled along a journey based on many chances taken, replying to the necessities they faced along the way before finding full enjoyment in the practice of medical and human genetics or dysmorphology. Additionally, and of equal importance, all exhibited an ability to evolve with their field of expertise as human genetics became human genomics with the development of novel technologies.

Evolution in the clinic: Maladaptive units and "minor anomalies".

It is here argued that the application of the term "minor anomalies" is often imprecise and likely outdated. In the past, the designation was used indiscriminately to refer to a great variety of unrelated morphogenetic phenomena. Also, the term does not discriminate between mild qualitative defects of development (mild malformations) and quantitative variants of normal structure. The human face was formed by natural and sexual selection. Morphological and morphogenetic analyses have shown that the human face with its skin, muscles, nerves, arteries, veins, glands, and lymphatics is a complex structure made up of progeny of ectoderm and mesoderm. Holoprosencephaly demonstrates graphically how these embryonic derivatives fit together sequentially. These derivatives are the adaptive units of the human organism, the result of stringent evolutionary forces uniting essential function to a minimum of structure. Before an "unusual" facial appearance is diagnosed as "abnormal", phenotype analysis is required to determine if there is a family resemblance or if it is a pleiotropic structure. The facial structures of chimps and humans are homologous by virtue of descent from a common ancestor (Darwin, 1859). Differences in the appearance of these species reflect adaptive divergence over some 6-7 million years of evolution while retaining over 98-99% genetic identity. Both species may develop Down syndrome, evidence of similarly retained developmental plasticity. It has occurred to us that Dobzhansky's axiom ("Nothing in biology makes sense except in the light of evolution") applies not only to genetics, but to all of medicine.

An evolutionary and developmental biology approach to gastroschisis.

Recent advances have now made it possible to speak of gastroschisis narrowly in morphogenetic terms invoking the Rittler-Beaudoin (R-B) model. This proceeds from the appreciation of gastroschisis as a congenital intestinal herniation (without cover or liver) within the primordial umbilical ring, mostly to the right side of a normally formed umbilical cord. Presently, it is unresolved whether this visceral prolapse represents failure of ring closure before return of the physiological hernia into the abdomen or rupture of the delicate amniotic/peritoneal membrane at the ring's edge to the right of the cord. Animal observations and experiments will be required to address this question effectively. If gastroschisis is, in fact, a primary malformation with the primordial umbilical ring as the developmental field involved, then homology implies potential gastroschisis in all amniotes with corresponding nourishment from yolk sac (aka omphalomesenteric) vessels going into the embryo and excretory products out via the ancient umbilical connection. It also implies homology of corresponding morphogenetic signal transduction cascades. We review the history of gastroschisis, its presumed pathogenesis, and the developmental biology of the amniotic umbilical ring from this perspective. Therefore, based on the animal and human evidence to date, we propose that gastroschisis is a primary midline malformation that involves the umbilical canal from amniotic to peritoneal space and its primordial umbilical ring, either through nonclosure or rupture of the membrane covering the area, mostly to the right, between the cord and the edge of the ring.

A De Novo FOXP1 Truncating Mutation in a Patient Originally Diagnosed as C Syndrome.

De novo FOXP1 mutations have been associated with intellectual disability (ID), motor delay, autistic features and a wide spectrum of speech difficulties. C syndrome (Opitz C trigonocephaly syndrome) is a rare and genetically heterogeneous condition, characterized by trigonocephaly, craniofacial anomalies and ID. Several different chromosome deletions and and point mutations in distinct genes have been associated with the disease in patients originally diagnosed as Opitz C. By whole exome sequencing we identified a de novo splicing mutation in FOXP1 in a patient, initially diagnosed as C syndrome, who suffers from syndromic intellectual disability with trigonocephaly. The mutation (c.1428 + 1 G > A) promotes the skipping of exon 16, a frameshift and a premature STOP codon (p.Ala450GLyfs*13), as assessed by a minigene strategy. The patient reported here shares speech difficulties, intellectual disability and autistic features with other FOXP1 syndrome patients, and thus the diagnosis for this patient should be changed. Finally, since trigonocephaly has not been previously reported in FOXP1 syndrome, it remains to be proved whether it may be associated with the FOXP1 mutation.

Santos syndrome is caused by mutation in the WNT7A gene.

We have recently described a family with a condition (Santos syndrome (SS; MIM 613005)) characterized by fibular agenesis/hypoplasia, hypoplastic femora and grossly malformed/deformed clubfeet with severe oligodactyly, ungual hypoplasia/anonychia, sometimes associated with mild brachydactyly and occasional pre-axial polydactyly. Autosomal dominant inheritance with incomplete penetrance was suggested, but autosomal recessive inheritance could not be ruled out, due to the high frequency of consanguineous matings in the region where the family lived. This report deals with linkage studies and exome sequencing, disclosing a novel variant in WNT7A, c.934G>A (p.Gly312Ser), as the cause of this syndrome. This variant was present in homozygous state in five individuals typically affected by the SS syndrome, and in heterozygous state in the son of one affected homozygous individual. The heterozygous boy presented only unilateral complex polysyndactyly and we hypothesize that he either presents a distinct defect or that his phenotype results from a rare, mild clinical manifestation of the variant in heterozygous state. Variants in WNT7A are known to cause at least two other limb defect disorders, the syndromes of Fuhrmann and Al-Awadi/Raas-Rothschild. Despite their variable degree of expressivity and overlap, the three related conditions can be differentiated phenotypically in most instances.

A De Novo Nonsense Mutation in MAGEL2 in a Patient Initially Diagnosed as Opitz-C: Similarities Between Schaaf-Yang and Opitz-C Syndromes.

Opitz trigonocephaly C syndrome (OTCS) is a rare genetic disorder characterized by craniofacial anomalies, variable intellectual and psychomotor disability, and variable cardiac defects with a high mortality rate. Different patterns of inheritance and genetic heterogeneity are known in this syndrome. Whole exome and genome sequencing of a 19-year-old girl (P7), initially diagnosed with OTCS, revealed a de novo nonsense mutation, p.Q638*, in the MAGEL2 gene. MAGEL2 is an imprinted, maternally silenced, gene located at 15q11-13, within the Prader-Willi region. Patient P7 carried the mutation in the paternal chromosome. Recently, mutations in MAGEL2 have been described in Schaaf-Yang syndrome (SHFYNG) and in severe arthrogryposis. Patient P7 bears resemblances with SHFYNG cases but has other findings not described in this syndrome and common in OTCS. We sequenced MAGEL2 in nine additional OTCS patients and no mutations were found. This study provides the first clear molecular genetic basis for an OTCS case, indicates that there is overlap between OTCS and SHFYNG syndromes, and confirms that OTCS is genetically heterogeneous. Genes encoding MAGEL2 partners, either in the retrograde transport or in the ubiquitination-deubiquitination complexes, are promising candidates as OTCS disease-causing genes.

Sudden infant death "syndrome"-Insights and future directions from a Utah population database analysis.

"Sudden Infant Death syndrome" (SIDS) represents the commonest category of infant death after the first month of life. As genome scale sequencing greatly facilitates the identification of new candidate disease variants, the challenges of ascribing causation to these variants persists. In order to determine the extent to which SIDS occurs in related individuals and their pedigree structure we undertook an analysis of SIDS using the Utah Population Database, recording, for example, evidence of enrichment for genetic causation following the back-to-sleep recommendations of 1992 and 1994. Our evaluation of the pre- and post back-to-sleep incidence of SIDS in Utah showed a decrease in SIDS incidence on the order of eightfold following back-to-sleep. An odds ratio of 4.2 for SIDS recurrence among sibs was identified from 1968 to 2013 which was similar to the odds ratio of 4.84 for death due to other or unknown cause among sibs of SIDS cases for the same time period. Combining first through thid degree relatives yielded an odds ratio of SIDS recurrence of 9.29 in the post-back-to-sleep (1995-2013) subset of SIDS cases where similar calculations of first-third degree relatives for the entire time period of 1968-2013 showed an odds ratio of 2.95. Expanded multigenertional pedigrees showing enrichment for SIDS were also identified. Based on these findings we hypothesize that post back-to-sleep SIDS, especially recurrences within a family, are potentially enriched for genetic causes due to the impact of safe sleeping guidelines in mitigating environmental risk factors. © 2016 Wiley Periodicals, Inc.

Annals of morphology fields and prepatterns. Editorial Festschrift for John C. Carey, MD, MPH.

The investigation of mammalian malformations began to approach human needs in the 19th century with, for example, Meckel's dissection of sibs with the "Meckel" syndrome, his intimation of Heredität as cause of the condition, his conclusion as to the common causal origin of this specific combination of congenital anomalies, the clear enunciation of the concept of primary malformations, the recognition that many human malformations are normal developmental states in other animals, and that some were normal anatomical states in remote ancestors and now still normal in collateral descendants (atavisms, Darwin's "reversions"; for example, four wings in dipterans, normal in dragonflies and their common ancestor). Later in the century, Wilhelm His Sr. had proposed a schematic map of "organ-forming districts" for prospective chick development, a concept that did not sit well with early workers in developmental biology (e.g., Boveri) until methods became available for a direct experimental "attack" on the embryo. This approach was pioneered by Spemann and Mangold through interspecies transplantation of embryonic rudiments with the spectacular result that set the research stage in developmental biology for the next many years. But it was not until mid-century that the late, great geneticist, Curt Stern, made the His model of chick development more intellectually and experimentally approachable with his meticulous analysis of cuticular appendages of Drosophila, one bristle and one bristle group (field) at a time, in mosaics or gynandromorphs, leading to the ingenious concept of prepatterns. As a basic scientist, Stern did not broaden prepatterns into medicine or to human malformations where it has now found a most gratifying application. This contribution to the Carey Festschrift is to summarize, briefly, field and prepattern theory. © 2016 Wiley Periodicals, Inc.

The power of stories in Pediatrics and Genetics.

On the occasion of the opening ceremony of the 43rd Sicilian Congress of Pediatrics, linked with Italian Society of Pediatrics SIP, SIN, SIMEUP, SIAIP and SINP, held in Catania in November 2015, the Organizing Committee dedicated a tribute to Professor John Opitz and invited him to give a Masters Lecture for the attendees at the Congress. The theme expounded was "Storytelling in Pediatrics and Genetics: Lessons from Aesop and from Mendel". The contribution of John Opitz to the understanding of pediatric clinical disorders and genetic anomalies has been extremely relevant. The interests of Professor John Opitz are linked not only to genetic disorders but also extend to historical medicine, history of the literature and to human evolution. Due to his exceptional talent, combined with his specific interest and basal knowledge in the genetic and pediatric fields, he is widely credited to be one of the best pediatricians in the world.

Screening of CD96 and ASXL1 in 11 patients with Opitz C or Bohring-Opitz syndromes.

Opitz C trigonocephaly (or Opitz C syndrome, OTCS) and Bohring-Opitz syndrome (BOS or C-like syndrome) are two rare genetic disorders with phenotypic overlap. The genetic causes of these diseases are not understood. However, two genes have been associated with OTCS or BOS with dominantly inherited de novo mutations. Whereas CD96 has been related to OTCS (one case) and to BOS (one case), ASXL1 has been related to BOS only (several cases). In this study we analyze CD96 and ASXL1 in a group of 11 affected individuals, including 2 sibs, 10 of them were diagnosed with OTCS, and one had a BOS phenotype. Exome sequences were available on six patients with OTCS and three parent pairs. Thus, we could analyze the CD96 and ASXL1 sequences in these patients bioinformatically. Sanger sequencing of all exons of CD96 and ASXL1 was carried out in the remaining patients. Detailed scrutiny of the sequences and assessment of variants allowed us to exclude putative pathogenic and private mutations in all but one of the patients. In this patient (with BOS) we identified a de novo mutation in ASXL1 (c.2100dupT). By nature and location within the gene, this mutation resembles those previously described in other BOS patients and we conclude that it may be responsible for the condition. Our results indicate that in 10 of 11, the disease (OTCS or BOS) cannot be explained by small changes in CD96 or ASXL1. However, the cohort is too small to make generalizations about the genetic etiology of these diseases.