Pathological and sonographic review of early isolated severe lower urinary tract obstruction and implications for prenatal treatment.

OBJECTIVE: To identify favorable renal histology in fetuses with early severe lower urinary tract obstruction (LUTO) and determine the best timing and selection criteria for prenatal surgery. METHODS: This multicenter, retrospective study included male fetuses with severe LUTO which died before 24 weeks of gestation during the period January 2000 to December 2018. Age-matched controls were used as reference standard for renal histology. Prenatal ultrasound features and fetal serum and/or urine ß2microglobulin level were retrieved and kidney histology slides (hematein-eosin-safran and α-smooth-muscle-actin (αSMA) immunostaining) were prepared and reviewed. αSMA-positive staining of the blastema is due to its aberrant differentiation into myofibroblastic cells. Cases were sorted into histopathologic groups (favorable or unfavorable) according to the blastema's morphology and αSMA labeling and the data of these groups were compared. RESULTS: Included in the study were 74 fetuses with a median gestational age at outcome of 17 + 6 (range, 13 + 0 to 23 + 5) weeks. Parenchymal organization was preserved in 48% of the kidneys. A blastema was present in 90% of the kidneys, but it was morphologically normal in only 9% and αSMA-negative in only 1% of them. Most (82%) fetuses had an unfavorable prognosis, and 36% of fetuses died ≤ 18 weeks and had severe renal lesions detected on histology (early unfavorable prognosis). A favorable renal prognosis was associated with an earlier gestational age (P = 0.001). Fetuses with LUTO had a significantly lower number of mature glomeruli (P < 0.001) compared with controls. However, there was no significant difference in the number of glomeruli generations between the early-unfavorable-prognosis group (≤ 18 weeks) and the group with a favorable prognosis (P = 0.19). A comparison of prenatal ultrasound features and biochemical markers between groups could not identify any prenatal selection criteria. CONCLUSIONS: Before 18 weeks, around 30% of fetuses with severe LUTO still have potential for kidney development. Identification of these cases would enable them to be targeted for prenatal therapy. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Heterogeneity in defining fetal corpus callosal pathology: systematic review.

OBJECTIVE: Fetal anomalies of the corpus callosum (CC) have been reported in the prenatal imaging literature since 1985, and, especially when isolated, pose challenges for both the patient and fetal medicine specialist. The purpose of this study was to review systematically the literature on prenatally diagnosed abnormalities of the CC, focusing on the terminology used to describe abnormalities other than complete agenesis of the CC, and to assess the heterogeneity of the nomenclature and definitions used. METHODS: This study was conducted in accordance with the PRISMA statement for reporting systematic reviews. A literature search was performed to identify prospective or retrospective case series or cohort studies, published in English, French, Italian, German or Spanish, reporting fetal imaging findings and describing anomalies of the CC. Quality and risk of bias of the studies were evaluated using the Newcastle-Ottawa scale and a modification of the scale developed by Conde-Agudelo et al. for other fetal imaging studies. The data extracted included the number of patients, the number of different anomalies identified, the descriptive names of the anomalies, and, where applicable, the definitions of the anomalies, the number of cases of each type of anomaly and the biometric charts used. Secondary tests used to confirm the diagnosis, as well as the postnatal or post-termination tests used to ascertain the diagnosis, were also recorded. RESULTS: The search identified 998 records, and, after review of titles and abstracts and full review of 45 papers, 27 studies were included initially in the review, of which 24 were included in the final analysis. These 24 studies had a broad range of quality and risk of bias and represented 1135 cases of CC anomalies, of which 49% were complete agenesis and the remainder were described using the term partial agenesis or nine other terms, of which five had more than one definition. CONCLUSIONS: In comparison to the postnatal literature, in the prenatal literature there is much greater heterogeneity in the nomenclature and definition of CC anomalies other than complete agenesis. This heterogeneity and lack of standard definitions in the prenatal literature make it difficult to develop large multicenter pooled cohorts of patients who can be followed in order to develop a better understanding of the genetic associations and neurodevelopmental and psychological outcomes of patients with CC anomalies. As this information is important to improve counseling of these patients, a good first step towards this goal would be to develop a simpler categorization of prenatal CC anomalies that matches better the postnatal literature. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Autosomal recessive IFT57 hypomorphic mutation cause ciliary transport defect in unclassified oral-facial-digital syndrome with short stature and brachymesophalangia.

The 13 subtypes of oral-facial-digital syndrome (OFDS) belong to the heterogeneous group of ciliopathies. Disease-causing genes encode for centrosomal proteins, components of the transition zone or proteins implicated in ciliary signaling. A unique consanguineous family presenting with an unclassified OFDS with skeletal dysplasia and brachymesophalangia was explored. Homozygosity mapping and exome sequencing led to the identification of a homozygous mutation in IFT57, which encodes a protein implicated in ciliary transport. The mutation caused splicing anomalies with reduced expression of the wild-type transcript and protein. Both anterograde ciliary transport and sonic hedgehog signaling were significantly decreased in subjects' fibroblasts compared with controls. Sanger sequencing of IFT57 in 13 OFDS subjects and 12 subjects with Ellis-Van Creveld syndrome was negative. This report identifies the implication of IFT57 in human pathology and highlights the first description of a ciliary transport defect in OFDS, extending the genetic heterogeneity of this subgroup of ciliopathies.

MOLAR TOOTH SIGN AND ACROCALLOSAL SYNDROME--A REPORT ON A POLISH FAMILY AND REVIEW OF KIF7 SYNDROMOLOGY.

Acrocallosal syndrome is a multiple congenital anomaly disorder characterized by postaxial and/or preaxial polydactyly, cutaneous syndactyly, macrocephaly, widely spaced eyes, absence or hypoplasia of the corpus callosum, and intellectual disability. It was first described by Albert Schinzel as early as in 1979, but the diagnosis of this syndrome still remains challenging. Here we report a family with 2 sibs with acrocallosal syndrome caused by novel mutations in KIF7. They present with features like molar tooth sign and hyperventilation that are not very typical in ACLS, but do occur in other ciliopathies, hence we also discuss the clinical heterogeneity of KIF7-associated disorders.

[Prenatal symptoms and diagnosis of inherited metabolic diseases]. / Maladies héréditaires du métabolisme : signes anténatals et diagnostic biologique.

Inherited metabolic diseases are mostly due to enzyme deficiency in one of numerous metabolic pathways, leading to absence of a compound downstream from and the accumulation of a compound upstream from the deficient metabolite(s). Diseases of intoxication by proteins (aminoacidopathies, organic acidurias, urea cycle defects) and by sugars (galactosemia, fructosemia) usually do not give prenatal symptoms since mothers protect their fetuses from pathological metabolite accumulation. A well-known exception is hypoplasia of corpus callosum, as is sometimes observed in nonketotic hyperglycinemia and sulfite oxidase deficiency. Conversely, women with phenylketonuria "poison" their fetus if they are not treated (spontaneous abortions, intrauterine growth restriction [IUGR], cardiac malformations, and brain disease). Amino acid synthesis defects can lead to prenatal symptoms: microcephaly in serine deficiency (detectable by amino acid analysis in fetal cord blood), and brain malformations in glutamine synthetase deficiency. Impaired folate metabolism is involved in a large fraction of neurodevelopmental defects referred to as spina bifida, yet the underlying genetic component(s) are largely unknown. Energy metabolism diseases caused by defects in the synthesis or utilization of relevant metabolites lead to organ dysfunctions or malformations, but prenatal diagnosis is usually impossible unless genetic analysis can rely on a previously affected child in the family. A somewhat intermediate condition is defects of mitochondrial beta-oxidation of fatty acids, as they may sometimes be symptomatic prenatally (notably the HELLP syndrome or other presentations), and in this case, organic acid and acylcarnitine analysis in amniotic fluid can be informative in the absence of an index case. In contrast, complex molecule diseases commonly give prenatal symptoms that may permit the diagnosis even in the absence of index cases: hydrops fetalis and skeletal anomalies in lysosomal storage diseases, hydrops fetalis in congenital disorders of glycosylation (CDG) and transaldolase deficiency, brain malformations in O-glycosylation defects, brain malformations, kidney cysts and skeletal anomalies in peroxysomal diseases (Zellweger syndrome), syndactyly, genitalia malformations, and IUGR in Smith-Lemli-Opitz (SLO) syndrome. Although many metabolic disorders show biochemical abnormalities during fetal development that are informative for prenatal diagnosis, only a fraction of them are clinically/sonographically symptomatic before birth, thus allowing for prenatal diagnosis in the absence of an index case, i.e., serine deficiency, some fatty acid beta-oxidation defects, transaldolase deficiency, lysosomal diseases, CDG, Zellweger syndrome, and SLO syndrome.

Epistatic interactions with a common hypomorphic RET allele in syndromic Hirschsprung disease.

Hirschsprung disease (HSCR) stands as a model for genetic dissection of complex diseases. In this model, a major gene, RET, is involved in most if not all cases of isolated (i.e., nonsyndromic) HSCR, in conjunction with other autosomal susceptibility loci under a multiplicative model. HSCR susceptibility alleles can harbor either heterozygous coding sequence mutations or, more frequently, a polymorphism within intron 1, leading to a hypomorphic RET allele. On the other hand, about 30% of HSCR are syndromic. Hitherto, the disease causing gene has been identified for eight Mendelian syndromes with HSCR: congenital central hypoventilation (CCHS), Mowat-Wilson (MWS), Bardet-Biedl (BBS), Shah-Waardenburg (WS4), cartilage-hair-hypoplasia (CHH), Smith-Lemli-Opitz (SLO), Goldberg-Sprintzsen (GSS), and hydrocephalus due to congenital stenosis of the aqueduct of sylvius (HSAS). According to the HSCR syndrome, the penetrance of HSCR trait varies from 5 to 70%. Trisomy 21 (T21) also predisposes to HSCR. We were able to collect a series of 393 patients affected by CCHS (n = 173), WS4 (n = 24), BBS (n = 51), MWS (n = 71), T21 (n = 46), and mental retardation (MR) with HSCR (n = 28). For each syndrome, we studied the RET locus in two subgroups of patients; i.e., with or without HSCR. We genotyped the RET locus in 393 patients among whom 195 had HSCR, and compared the distribution of alleles and genotypes within the two groups for each syndrome. RET acts as a modifier gene for the HSCR phenotype in patients with CCHS, BBS, and Down syndrome, but not in patients with MWS and WS4. The frequent, low penetrant, predisposing allele of the RET gene can be regarded as a risk factor for the HSCR phenotype in CCHS, BBS, and Down syndrome, while its role is not significant in MWS and WS4. These data highlight the pivotal role of the RET gene in both isolated and syndromic HSCR.

Pathophysiology of syndromic combined pituitary hormone deficiency due to a LHX3 defect in light of LHX3 and LHX4 expression during early human development.

The pathophysiology of combined pituitary hormone deficiency (CPHD) is just beginning to be elucidated, with mutations in genes encoding transcription factors expressed at different stages of pituitary development. Among them, the two closely related genes, LHX3 and LHX4, are believed to share redundant biological properties. The patients with a LHX3 mutation display a CPHD phenotype, associated with a rigid cervical spine. This latter feature, not reported in Lhx3-/- and Lhx4-/- mice nor in patients with a LHX4 defect, prompted us to study the molecular consequences of a previously identified LHX3 23-bp deletion and to determine the LHX3 and LHX4 expression patterns during early human development. This deletion, which results in the skipping of one coding exon, would lead to a protein with no transcriptional capability. Using in situ hybridization, we show that LHX3 and LHX4 are expressed in the developing human pituitary and along the rostro-caudal length of the spinal cord; here, both transcripts are detected in the ventral part giving rise to motorneurons and interneurons. However, whereas LHX3 is expressed at all stages studied, LHX4 expression is transient, and, at 6 weeks of development, is stronger at the caudal than at the cervical level.

Renal coloboma syndrome.

OBJECTIVE: To characterize the ocular features of renal coloboma syndrome. DESIGN: Prospective, observational case series. PARTICIPANTS: Twelve patients referred by the pediatric nephrology clinic and the ophthalmic records of five additional patients. METHODS: For each patient, age at the time of examination, gender, renal function, and presence of a mutation in the PAX2 gene were noted. All patients underwent measurement of visual acuity and anterior and posterior segment examination with fundus photography. Goldmann visual fields were tested in four cases. MAIN OUTCOME MEASURES: Visual acuity, optic disc abnormalities, and mutation in the PAX2 gene. RESULTS: Mean age was 21.5 years. Renal failure was mild in 6 patients and severe in 11 patients. A mutation in the PAX2 gene was identified in nine patients, without correlation to the ocular phenotype. Ocular features could be divided into five groups: optic disc dysplasia limited to an unusual pattern of retinal vessels without functional consequence; optic disc pit with normal visual acuity and blind spot enlargement; large optic disc coloboma; large coloboma of the optic disc and adjacent retina; morning glory anomaly (these last three conditions were accompanied by poor visual acuity). Fundus abnormalities were symmetrical in most cases and unrelated to renal status. CONCLUSIONS: Ophthalmic and renal characteristics of the renal coloboma syndrome are highly variable. The need for dialysis or renal transplantation can occur early in life or several years later. A wide range of ocular abnormalities located in the posterior segment can be observed. Mild optic disc dysplasia or pit have no functional consequence and can be underdiagnosed. More severe colobomas or related abnormalities, such as morning glory anomaly, often lead to poor visual acuity. Molecular biology allows detection of the mutations in the PAX2 gene, but can be negative in approximately 50% of cases. The observation of an optic disc coloboma or related abnormality stimulates the ophthalmologist to propose simple nephrologic investigations to check for renal hypoplasia, a potentially life-threatening disease. Conversely, renal hypoplasia stimulates the nephrologist to ask for a fundus examination to confirm the diagnosis and check for complications such as retinal detachment.

PAX2 mutations in oligomeganephronia.

BACKGROUND: Oligomeganephronia (OMN) is a rare congenital and usually sporadic anomaly. It is characterized by bilateral renal hypoplasia, with a reduced number of enlarged nephrons. The mechanisms involved in this deficient nephrogenesis are unknown. The paired box transcription factor PAX2 plays a fundamental role in renal development. Heterozygous Pax2 mutants in mice are characterized by renal hypoplasia and retinal defects, and in humans, PAX2 mutations have been described in the renal-coloboma syndrome. METHODS: To assess whether OMN could be related to PAX2, we searched for PAX2 mutations in nine patients presenting with sporadic and apparently isolated OMN. RESULTS: Heterozygous PAX2 mutations were found in three patients. A limited optic nerve coloboma was secondarily detected in two cases and a very mild optic disk dysplasia in one patient. None of these patients had visual impairment. CONCLUSIONS: Ocular anomaly and PAX2 mutations should be sought in all patients with OMN.

Identification and characterization of an inner ear-expressed human melanoma inhibitory activity (MIA)-like gene (MIAL) with a frequent polymorphism that abolishes translation.

To discover new cochlea-specific genes as candidate genes for nonsyndromic hearing impairment, we searched in The Institute of Genome Research database for expressed sequence tags isolated from the cochlea only. This led to the cloning and characterization of a human gene named melanoma inhibitory activity-like (MIAL; HGMW-approved symbol OTOR alias MIAL) gene. In situ hybridization revealed MIAL expression in a cell layer beneath the sensory epithelium of cochlea and vestibule of human fetal inner ear. No other human tissue, except fetal brain, showed expression of MIAL when analyzed by in situ hybridization or reverse transcription-polymerase chain reaction. The cDNA of the mouse homologue was also cloned and mapped about 80 cM from the top of mouse chromosome 2. In mouse, Mial was also expressed in the cochlea and the vestibule of the inner ear, as well as in brain, eye, limb, and ovary. Expression in mammalian cell cultures showed that MIAL is translated as an approximately 15-kDa polypeptide that is assembled into a covalently linked homodimer, modified by sulfation, and secreted from the cells via the Golgi apparatus. In the human MIAL gene, a frequent polymorphism was discovered in the translation initiation codon (ACG instead of ATG). Of 505 individuals, 48 (9.5%) were ATG/ACG heterozygous and 1 (0.2%) was homozygous for ACG. No MIAL protein was synthesized in cells transfected with cDNA of the ACG allele. The inner ear-restricted expression pattern and the existence of an inactive allele suggest that MIAL may contribute to inner-ear dysfunction in humans.

JAGGED1 gene expression during human embryogenesis elucidates the wide phenotypic spectrum of Alagille syndrome.

Mutations of the JAGGED1 gene, encoding a NOTCH receptor ligand, cause Alagille syndrome (AGS), a complex malformative disorder affecting mainly the liver, heart, vertebrae, eye, and face. Minor and occasional features involving kidney, pharynx, systemic arteries, skeleton, and ear are in some cases associated with the syndrome. To describe the expression of JAGGED1 during human embryogenesis and to study its relationship with all the features of AGS, we performed in situ hybridization studies on human embryos and fetal tissue sections. JAGGED1 was mainly expressed in the cardiovascular system. In the liver, JAGGED1 transcripts were only detected in blood vessels. JAGGED1 was also expressed in other structures of mesenchymal origin (distal mesenchyme of limb buds; mesonephric and metanephric tubules of the kidney) and in epithelial structures including the ciliary margin of the retina and the posterior part of the lens, the ventral epithelium of the otic vesicle, the neurosensory epithelium of the ear vestibule, the epithelium of pharyngeal arches, and the developing central nervous system. The strong JAGGED1 expression during human embryo- and feto-genesis both in the vascular system and in other mesenchymal and epithelial tissues implicates abnormal angiogenesis in the pathogenesis of Alagille syndrome and particularly the paucity of interlobular bile ducts. However, it is probably not the only mechanism of the disease. Except for the central nervous system, there is a strong correlation between JAGGED1 expression and all the features of AGS. This implies that the features occasionally associated with the syndrome are not coincidental.

Expression of the PTEN tumour suppressor protein during human development.

The tumour suppressor gene PTEN, localized to 10q23.3, is the susceptibility gene for Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba (BRR) syndrome, two hamartoma syndromes with an increased risk of breast and thyroid tumours. Somatic mutations have been found in a variety of human tumours. Functional studies have revealed that PTEN plays a fundamental role in cellular growth, death, adhesion and migration. RNA in situ hybridization using the pten coding region in mouse embryos showed ubiquitous transcription, providing evidence that pten could play a versatile role throughout murine development. Nothing is known regarding the pattern of PTEN expression during human development. Here, we present the pattern of PTEN expression during human development using a specific monoclonal antibody and examine the relationship of the temporal and spatial expression pattern to the clinical manifestations of CS and BRR, the somatic genetic data in sporadic cancers, the murine knockout models and the RNA expression data in mouse embryos. We observed mainly high-level PTEN expression in tissues (e.g. skin, thyroid and central nervous system) known to be involved in CS and BRR. In addition, we identified tissues (e.g. peripheral nervous system, autonomomic nervous system and upper gastrointestinal tract) with high PTEN expression not commonly known to play a role in these syndromes nor in sporadic tumorigenesis in those organs. This knowledge may help in identifying roles for PTEN which, as of today, are unknown or even unsuspected.

Expression of the sonic hedgehog gene in human embryos with neural tube defects.

BACKGROUND: To estimate the rate of malformations observed during early human development, a series of 38,913 first-trimester abortions were studied. Neural tube defects (NTD) were found in 57 cases. METHODS: A histological study of serial sections performed in 25 embryos revealed a spectrum of axial structure abnormalities. Expression of the SHH gene was studied by in situ hybridization in one case of CRS and in two cases of SB. RESULTS: A cervical notochord duplication was always found in craniorachischisis (CRS, n = 8), but not in spina bifida (SB, n = 10) or diplomyelia (split cord malformation, n = 3). In the embryo with CRS, expression of SHH was found in both domains, corresponding to the duplicated part of the notochord, whereas a single signal was observed in the nonduplicated part. This expression was associated at the cervical level of the open neural tube with a broad SHH expression domain and with two or even three domains in its lumbar region, suggesting multiple functional floor plates. Similarly, in two embryos with SB, two domains of SHH expression were found in the ventral neural tube. CONCLUSIONS: Our findings suggest that notochord splitting in the cervical region might be involved in the pathogenesis of CRS. Interestingly, similar notochord abnormality and altered expression of the shh gene are observed in Lp mice with NTD. This suggests that the Lp gene could be a candidate gene for human CRS. Further studies are needed to establish the primary event responsible for the notochord splitting and for the abnormal expression of the SHH gene in the floor plate in embryos with CRS and SB.

[Molecular genetics of Hirschsprung disease: a model of multigenic neurocristopathy]. / Génétique moléculaire de la maladie de Hirschsprung: un modèle de neurocristopathie multigénique.

Hirschsprung's disease (HSCR, aganglionic megacolon) is a frequent congenital malformation regarded as a multigenic neurocristopathy. Three susceptibility genes have been recently identified in HSCR, namely the RET proto-oncogene, the endothelin B receptor (EDNRB) gene, and the endothelin 3 (EDN3) gene. RET gene mutations were found in significant proportions of familial (50%) and sporadic (15-20%) HSCR, while homozygosity for EDNRB or EDN3 mutations accounted for the rare HSCR-Waardenburg syndrome (WS) association. More recently, heterozygous EDNRB an EDN3 missense mutations have been reported in isolated HSCR patients. Some of these results were obtained after the identification of mouse genes whose natural or site-directed mutations resulted in megacolon and coat color spotting. There is also conclusive evidence for the involvement of other independent loci in HSCR. In particular, the recent identification of neurotrophic factors acting as RET ligands (GDNF and Neurturin) provide additional candidate genes for HSCR. The dissection of the genetic etiology of HSCR disease may then provide a unique opportunity to distinguish between a polygenic and a genetically heterogeneous disease, thereby helping to understand other complex disorders and congenital malformations hitherto considered as multifactorial in origin. Finally, the study of the molecular bases of HSCR is also a step towards the understanding of developmental genetics of the enteric nervous system giving support to the role of the tyrosine kinase and endothelin-signaling pathways in the development of neural crest-derived enteric neurons in human.

Expression of the RET proto-oncogene in human embryos.

The patterns of RET proto-oncogene expression in mouse, rat, and chicken and the anomalies observed in targeted RET mutants suggest that RET plays a major role in development of mouse enteric nervous system and in kidney organogenesis. Here, we report on in situ hybridization studies describing the pattern of RET proto-oncogene expression during early development of human embryos between 23 and 42 days. We show that the RET gene is expressed in the developing kidney (nephric duct, mesonephric tubules, and ureteric bud), the presumptive enteric neuroblasts of the developing enteric nervous system, cranial ganglia (VII+VIII, IX, and X) and in the presumptive motor neurons of the spinal cord. Yet, despite the high level of RET gene expression in the kidney and in the motor neurons of the developing central nervous system in human embryos, only rare cases with renal agenesis have been reported in Hirschsprung disease patients, and no clinical evidence of spinal cord involvement has been shown in patients carrying RET germline mutations (i.e., multiple endocrine neoplasia syndromes and Hirschsprung disease).