Discordant phenotype in monozygotic twins with Fryns syndrome

Diaphragmatic Hernia as a Prenatal Feature of Glycosylphosphatidylinositol Biosynthesis Defects and the Overlap With Fryns Syndrome - Literature Review

Fryns syndrome is an autosomal recessive multiple congenital anomaly syndrome, with diaphragmatic defects and secondary lung hypoplasia as cardinal features. Despite it was reported first in 1979, its exact etiology has not been established to date. With this review, we would like to draw attention to the prenatal presentation of multiple congenital anomalies syndromes, resulting from defects in the synthesis of glycosylphosphatidylinositol anchors, to be considered in a prenatal assessment of fetuses with DH and Fryns-like phenotype.

Can syndromic macrocephaly be diagnosed in utero?

OBJECTIVES

To compare the outcomes of fetuses with apparently isolated macrocephaly and those with associated findings, and to compare prenatal findings with postnatal diagnoses in children with syndromic macrocephaly.

METHODS

We reviewed the files of all patients referred for suspected fetal macrocephaly, during a 10-year period from 2000, to a large prenatal diagnosis unit with expertise in fetal neurology counseling. Macrocephaly was defined as head circumference (HC) > 2 SDs of the norm. Patients with confirmed HC > 2 SD were identified and contacted, and their development was evaluated.

RESULTS

Adequate data for analysis were available for 98 patients, in 82 of whom the fetal macrocephaly was considered isolated (Group A), and in 16 of whom associated fetal anomalies were identified (Group B). Macrocephaly was diagnosed earlier in Group B patients (28.4 vs. 32.3 weeks, P = 0.069), and the HC in Group B patients was larger (Z-score 2.95 vs. 2.3, P < 0.001). From Group A there were 81 liveborn; one of whom was diagnosed as having infantile autism. From Group B, there were nine liveborn. The associated central nervous system findings, as demonstrated by ultrasound and magnetic resonance imaging, included mild ventriculomegaly, malformations of cortical development, callosal abnormalities, overdeveloped sulcation, large cavum septi pellucidi, large subarachnoid spaces, mega cisterna magna, periventricular pseudocyst, open operculum and vermian dysgenesis. Syndromic diagnosis was made in utero in five fetuses and after birth in three. In eight patients, associated malformations were confirmed after birth but a specific diagnosis was not reached.

CONCLUSIONS

When fetal macrocephaly is associated with other brain or systemic anomalies, syndromic macrocephaly can be diagnosed in utero. Fetuses with syndromic macrocephaly have a significantly larger HC, usually > 2.5 SD above the mean. Isolated macrocephaly, particularly when the HC is < 2.5 SD above the norm, may be clinically benign.

Identical but not the same: the value of discordant monozygotic twins in genetic research

Monozygotic (MZ) twins show remarkable resemblance in many aspects of behavior, health, and disease. Until recently, MZ twins were usually called "genetically identical"; however, evidence for genetic and epigenetic differences within rare MZ twin pairs has accumulated. Here, we summarize the literature on MZ twins discordant for Mendelian inherited disorders and chromosomal abnormalities. A systematic literature search for English articles on discordant MZ twin pairs was performed in Web of Science and PubMed. A total number of 2,016 publications were retrieved and reviewed and 439 reports were retained. Discordant MZ twin pairs are informative in respect to variability of phenotypic expression, pathogenetic mechanisms, epigenetics, and post-zygotic mutagenesis and may serve as a model for research on genetic defects. The analysis of single discordant MZ twin pairs may represent an elegant approach to identify genes in inherited disorders.

Syndrome de Fryns. Présentation de 3 nouvelles observations

BACKGROUND

Fryns syndrome is a lethal autosomal recessive syndrome which includes congenital diaphragmatic hernia (CDH), pulmonary hypoplasia, cranio-facial manifestations including a coarse face, a cleft palate / lip and cloudy corneae, distal limb hypoplasia and internal malformations including central nervous system, cardiovascular, gastrointestinal, urogenital and skeletal anomalies.

CASES REPORT

We report on 3 patients with Fryns syndrome in the french Indian Ocean islands (La Réunion and Mayotte islands). Pregnancies were complicated by polyhydramnios. All patients had coarse face, cloudy corneae, cleft lip / palate or high-arched palate, hypoplastic nails and brachytelephalangy. They died in the neonatal period. Two had CDH and 1 did not have a diaphragmatic involvement but a severe respiratory distress syndrome with refractory hypoxemia. Cytogenetic studies of blood lymphocytes and skin fibroblasts were normal.

CONCLUSIONS

Fryns syndrome is the most common multiple congenital anomaly associated with CDH. The diagnosis is strongly suggested when CHD and brachytelephalangy are associated. Phenotypes with CDH similar to Fryns syndrome have been described with cytogenetic aberrations with G-banded chromosome analysis and submicroscopic chromosome deletions detected by high resolution karyotyping or array comparative genomic hybridization (CGH). Exclusion of chromosome aberrations (including isochromosome 12p in skin fibroblasts) is needed prior to making the diagnosis of Fryns syndrome. In sporadic cases, high resolution karyotyping or array CGH should be performed for correct diagnosis and genetic counselling.

Cardiovascular malformations in Fryns syndrome: is there a pathogenic role for neural crest cells?

We performed a comprehensive literature and case report review to characterize the cardiovascular malformations (CVMs) associated with Fryns syndrome (OMIM #229850), a multiple congenital anomaly/mental retardation syndrome consisting of diaphragmatic defects, significant pulmonary hypoplasia, distinctive facial appearance, distal digital hypoplasia, and numerous other external and internal anomalies. A total of 112 patients meeting diagnostic guidelines for Fryns syndrome were identified, of whom 82 met narrowly defined criteria (Group I) and 30 met broader diagnostic criteria (Group II). Twelve patients reported as having Fryns syndrome with atypical features (Group III) were also analyzed. A CVM was reported in 51% (42 of 82) of Group I patients, most commonly an atrial or ventricular septal defect (VSD) (23 of 42, 55%). Conotruncal and aortic arch CVMs were common (11 of 42, 26%), but not significantly so compared to the general population of infants to age 1 year [Ferencz et al., 1997]. Recognizing that minor septal defects associated with congenital diaphragmatic hernia (CDH) may occur in response to altered hemodynamics (instead of being a bonafide CVM), we excluded four patients reported as having hemodynamically insignificant VSDs. Following these exclusions, conotruncal CVMs were found more commonly than in the general population (11 of 38, 29%, P < or = 0.025). In Group II, 9 of 30 (30%) had a CVM with no predominant type among the small number of cases reviewed. Among the atypical Fryns syndrome patients in Group III, half (6 of 12, 50%) had a CVM; most (4 of 6, 67%) were conotruncal, in particular, type B interrupted aortic arch (3 of 4). Patients with Fryns syndrome have a high rate of CVMs, warranting thorough cardiac evaluation including echocardiogram (fetal and/or postnatal) in all patients, similar to the evaluation for other patients with diaphragmatic hernia. The possible association between conotruncal CVMs and Fryns syndrome may provide additional support for an etiologic role of genes related to neural crest cell development in the pathogenesis of Fryns syndrome and hence, congenital diaphragmatic hernia.

The genetics of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high mortality and morbidity. A clear understanding of the pathogenesis of CDH is critical for determining prognosis and planning treatment, but to date, information on the genetic etiology of both nonsyndromic and syndromic CDH is limited. This paper summarizes the current knowledge concerning the genes, syndromes, and chromosome aberrations associated with CDH in humans and in animal model systems. Mutations in several different genes have been described in syndromic CDH, but there is only one mutation that has been reported in non-syndromic CDH to date. However, animal models suggest that genes involved in cell migration, myogenesis, and connective tissue formation are critical to normal diaphragm formation, and these data provide a starting point for the search for other genes involved in the pathogenesis of CDH.

Fryns syndrome with Hirschsprung disease: Support for possible neural crest involvement

Fryns syndrome is an autosomal recessive multiple congenital anomaly/mental retardation syndrome characterized by coarse face, distal limb hypoplasia, and diaphragmatic anomalies. We describe a newborn girl with Fryns syndrome and Hirschsprung disease, an association that has been reported in five previous cases. These patients support the hypothesis that the neural crest plays a role in the pathogenesis of Fryns syndrome. Clinically asymptomatic or subtle anomalies that are in the spectrum of neural crest maldevelopment should be sought in all patients with Fryns syndrome including stillbirths, neonatal deaths, as well as long-term survivors. We suspect that the clinical observation about Hirschsprung disease and Fryns syndrome may provide insight into its molecular mechanisms and candidate genes.

Eye abnormalities in Fryns syndrome

Fryns syndrome is a rare, generally lethal, autosomal recessive multiple congenital anomaly (MCA) syndrome first described in 1979. Patients with the syndrome present with the classical findings of cloudy cornea, brain malformations, diaphragmatic defects, and distal limb deformities. Over 70 patients have been reported revealing a wide variety of phenotypic features. Although initially considered a major feature of Fryns syndrome, cloudy cornea has been relegated as a minor diagnostic sign and not commonly reported in patients since the original description. However, eye findings per se are not uncommon. Abnormal eye findings occasionally reported in Fryns syndrome potentially result in amblyopia and blindness, profoundly affecting neurologic outcome of those who survive the neonatal period. We reviewed 77 reported patients with Fryns syndrome and summarized the abnormal eye findings identified in 12 of the reported cases. In addition, we contribute three new patients with Fryns syndrome, one of which demonstrated unilateral microphthalmia and cloudy cornea.

A case of Fryns syndrome without diaphragmatic hernia and review of the literature

We report on a child with Fryns syndrome who showed a characteristic coarse hirsute facial appearance, bilateral cleft lip and palate, cardiac and renal anomalies, dilated bowel and distal limb abnormalities. However, diaphragmatic hernia, which is considered a cardinal feature in this condition, was absent in our patient. The parents were consanguineous supporting autosomal recessive inheritance.

Non-immune hydrops and superior vena cava syndrome due to diaphragmatic hernia in one twin

BACKGROUND

In a monochorionic twin gestation, hydrops in one fetus often results from placental transfusion, accompanied by intrauterine growth restriction (IUGR) of the non-hydropic fetus.

CASE

A 35-year-old G11P9 presented with hydrops and IUGR of one of a monochorionic-diamniotic gestation. Extensive testing failed to reveal etiology for hydrops. The patient was delivered at 30 weeks gestation after non-reassuring fetal monitoring. The hydropic baby could not be adequately ventilated and expired in the early post-partum period. A diagnosis of superior vena cava syndrome and pulmonary hypoplasia secondary to right-sided congenital diaphragmatic hernia (CDH) was made neonatally.

CONCLUSION

Right-sided CDH can be difficult to diagnose by sonography at times because of the echogenic similarity of liver and lung, and may be suspected from signs of pericardial effusion and ascites.

Fryns syndrome: A review of the phenotype and diagnostic guidelines

Fryns syndrome (FS) is the commonest autosomal recessive syndrome associated with congenital diaphragmatic hernia (CDH) and comprises CDH, pulmonary hypoplasia, craniofacial anomalies, distal limb hypoplasia, and internal malformations. Although there have been more than 50 case reports on probands with FS, the diagnostic guidelines were formulated from a review of eight patients and modifications to the guidelines have only once been suggested. Recently, several case reports have described new anomalies in FS and other papers have highlighted the variation in expressivity found in FS. This paper examines the medical literature on FS to define the phenotype and to review the diagnostic guidelines. We conclude that CDH with brachytelephalangy and/or nail hypoplasia is strongly suggestive of the diagnosis and that pulmonary hypoplasia, craniofacial dysmorphism, orofacial clefting, and polyhydramnios are sufficiently frequent to be diagnostically useful. Other distinctive malformations that are consistent with FS include ventricular dilatation or hydrocephalus, agenesis of the corpus callosum, neuronal or cerebellar heterotopias, abnormalities of the aorta, renal cysts, dilatation of the ureters, bicornuate uterus, renal dysplasia, proximal thumbs, and broad clavicles.

Cleft-palate lateral synechia syndrome: insight into the phenotypic spectrum of Fryns syndrome?

BACKGROUND

In 1972, Fuhrmann et al. (Humangenetik 1972;14:196-203) described a novel syndrome consisting of cleft palate (CP) and lateral synechiae (LS) between the palate and the floor of the mouth. This constellation of malformations, since denoted as cleft-palate lateral synechiae syndrome (CPLS), is a rare syndrome; only five cases have been reported since the original description. Because of the paucity of recognized cases, little is known regarding the phenotypic spectrum of this presumably autosomal dominant condition.

CASES

We report two unrelated patients who presented with remarkably similar phenotypic features, including multiple intraoral synechiae (filiforme intraalveolar bands), cleft palate, micrognathia, and redundant lower lip tissue. Their phenotypic findings indicate a diagnosis of CPLS; however, case 3 (the monozygotic twin of case 2) had classic phenotypic features of Fryns syndrome.

CONCLUSIONS

This report presents two new cases of CPLS, and suggests that the CPLS phenotype may represent the mild end of the Fryns syndrome phenotypic spectrum. Supplementary material for this article can be found on the Birth Defects Research (Part A) website (http://www.interscience.wiley.com/ jpages/1542-0752/suppmat/67/fig5.xls).

Monozygotic twins with a severe form of Alagille syndrome and phenotypic discordance

Alagille syndrome is an autosomal dominant disorder affecting multiple organ systems, predominantly the liver, heart, skeleton, eye, face, and kidney. The phenotype in Alagille syndrome is highly variable both within and between families. We report monozygotic twins with Alagille syndrome concordant for a mutation in Jagged1 but discordant for clinical phenotype. The twins' monozygosity was confirmed by molecular testing. A de novo splice site mutation was identified in exon 6 (1329 + 2T --> G) in both children. Both twins display a severe form of Alagille syndrome; however, one twin has a severe pulmonary atresia with mild liver involvement, while the other has tetralogy of Fallot and severe hepatic involvement, which has required liver transplantation. Potential mechanisms for phenotypic variability among monozygotic twins are discussed. This is the first reported case of discordance in phenotype in monozygotic twins with Alagille syndrome. This case implies that genotypic variations alone do not explain the clinical variability seen in Alagille syndrome and supports the contributory role of nongenetic factors in phenotype determination.

Documentation of anomalies not previously described in Fryns syndrome

We report on a case of Fryns syndrome with microcephaly, multiple facial anomalies, hypoplasia of distal phalanges, diaphragmatic defect with a thin, translucent diaphragm, microphthalmia (right), anophthalmia (left), and multiple midline developmental defects including gastroschisis, central nervous system defects including left arrhinencephaly and cerebellar hypoplasia, midline cleft of the upper lip, alveolar ridge and maxillary bone, and cleft nose with bilateral choanal atresia. These defects add to our knowledge of the phenotype of Fryns syndrome.

Fryns syndrome in children with congenital diaphragmatic hernia

PURPOSE

Fryns syndrome is characterized by multiple congenital anomalies including Congenital Diaphragmatic Hernia (CDH), and has a reported poor prognosis with a survival rate during the neonatal period of approximately 15%. This report details the management and outcome of patients with Fryns syndrome and CDH.

METHODS

Records of all liveborn patients with CDH between 1995 and 2001 in 83 hospitals were entered into the CDH database. Those with Fryns syndrome were reviewed retrospectively.

RESULTS

A total of 1,833 patients were entered in the database, 23 of these had Fryns (1.3%). All patients experienced early distress requiring intubation. Ten patients (43%) were found to have other major anomalies. Seven patients underwent surgical repair at an average age of 7.5 days (range, 6 hours to 14 days). Mortality rate was 83% compared with 33% of patients with unilateral CDH (P =.01). Ten patients died within the first 24 hours. The parents of 6 patients withdrew support. Of the 4 survivors, 3 have marked developmental delay, whereas the fourth has not yet undergone formal assessment.

CONCLUSIONS

The prognosis of infants with Fryns syndrome and congenital diaphragmatic hernia remains grim. Early genetic counseling and recognition of lethal anomalies may assist in determining which patients may survive.

Newborn with anophthalmia and features of Fryns syndrome

We report a newborn female with craniofacial malformations, bilateral anophthalmia, large abnormally shaped ears, short neck, small distal phalanges and nails, left diaphragmatic hernia, hypoplastic optic nerves, severe pulmonary hypoplasia, and an accessory spleen, and describe the autopsy findings. The infant expired at 18 h of life. The features were most consistent with Fryns syndrome although other conditions were considered including Matthew Wood syndrome. Anophthalmia, to our knowledge, has not been reported previously in Fryns syndrome; however, eye findings are common, particularly microphthalmia and cloudy cornea.