Neu Laxova syndrome in two Egyptian families

Fetal Phenotyping and Whole Exome Sequencing for 12 Egyptian Families With Serine Biosynthesis Defect: Novel Clinical and Allelic Findings With a Founder Effect

OBJECTIVE

The purpose of this study was to improve our understanding of severe serine biosynthesis defects through a comprehensive description of prenatal, and postnatal manifestations and the mutational spectrum in a new cohort of 12 unrelated Egyptian Families.

METHODS

Detailed fetal ultrasound examination, postnatal assessment, and whole exome sequencing (WES) were performed in a cohort of 12 fetuses with suspected Neu-Laxova syndrome (NLS), the most severe expression of serine biosynthesis defects. Additionally, a comprehensive review of the literature was conducted by merging the data from all the molecularly-confirmed cases with ours to gain a better understanding of the clinical variability of NLS.

RESULTS

Novel clinical manifestations including intrauterine convulsions, hemivertebrae, natal teeth, holoprosencephaly, and rhombencephalosynapsis were observed. Molecular analysis identified 7 and 2 likely disease-causing variants in the PSAT1 and PHGDH genes, respectively. Four of them were novel, including the c.734G>A missense variant in PSAT1, which has been proposed to be a founder variant among Egyptians.

CONCLUSION

The present cohort expands the spectrum of serine biosynthesis disorders. Moreover, it illuminates the role of prenatal exome sequencing in lethal conditions constituting the most severe end of already-known human diseases.

Prenatal Diagnosis of Neu–Laxova Syndrome

Neu–Laxova syndrome is a rare and lethal genetic disease with autosomal recessive inheritance involving abnormalities of multiple systems. It was first reported in 1971. Since then, just eighty-eight cases have been reported. The syndrome is characterized by early and severe growth restriction, and craniofacial anomalies, such as microcephaly, hypertelorism and other malformations, resulting in quite characteristic features. Additionally, it might appear as generalized edema, flexion contractures and other malformations of the extremities, abnormalities in the CNS (central nervous system), skin (severe ichthyosis), and genitourinary and cardiac abnormalities. We present the case of a patient who had her first pregnancy with a fetus with Neu–Laxova syndrome diagnosed in our center during the second-trimester ultrasound. The ultrasound findings suggested the diagnosis, which was confirmed with a genetic study of the amniotic fluid: the variant of the PSAT1 gene, associated with NLS (Neu–Laxova syndrome) 2 in homozygosis. Moreover, there was a second pregnancy with a fetus carrying the same mutation in heterozygosis. In addition, we have carried out a review of published literature about this disease up to the present time.

[Neu-Laxova syndrome: Three case reports and a review of the literature]

INTRODUCTION

The Neu-Laxova syndrome (NLS) is a rare autosomal recessive and early lethal disorder. It is characterized by severe intra-uterine growth retardation, abnormal facial features, ichthyotic skin lesions and severe central nervous system malformations, especially microlissencephaly. Others characteristic features associated with fetal hypokinesia sequence, including arthrogryposis, subcutaneous edema and pulmonary hypoplasia, are frequently reported in NLS.

PATIENTS AND METHODS

The clinicopathological characteristics of NLS are described in three cases with striking prenatal diagnostic findings and detailed post-mortem examinations. A review of the literature is undertaken with a focus on molecular basis.

RESULTS

We present three new patients with NLS: one stillbirth male and two female newborns, delivered at 29, 35 and 40 weeks of gestational age, respectively. Characteristic ultrasound findings included hydramnios, severe intra-uterine growth restriction, craniofacial and cental nervous system anomalies. The cytogenetic study, performed in one case, was normal. The post-mortem examination revealed characteristic abnormalities in all three cases, that allowed to make a prompt diagnosis of the NLS. Data from these patients suggest that the NLS represents a heterogeneous phenotype. This feature has been highlighted in the literature.

CONCLUSION

The SNL is a lethal developmental disorder characterized by phenotypic heterogeneity with striking neurological defects. It is underpinned by genetic heterogeneity. It can be caused by mutations in all three genes involved in de novo L-serine biosynthesis: PHGDH, PSAT1 and PSPH. Hence, the NLS constitutes the most severe end of already known human disease, i.e. serine-deficiency disorder.

Identification of a premature stop codon mutation in the PHGDH gene in severe Neu-Laxova syndrome-evidence for phenotypic variability

In some cases Neu-Laxova syndrome (NLS) is linked to serine deficiency due to mutations in the phosphoglycerate dehydrogenase (PHGDH) gene. We describe the prenatal and postnatal findings in a fetus with one of the most severe NLS phenotypes described so far, caused by a homozygous nonsense mutation of PHGDH. Serial ultrasound (US) and pre- and postnatal magnetic resonance imaging (MRI) evaluations were performed. Prenatally, serial US evaluations suggested symmetric growth restriction, microcephaly, hypoplasia of the cerebellar vermis, micrognathia, hydrops, shortened limbs, arthrogryposis, and talipes equinovarus. The prenatal MRI confirmed these findings prompting a diagnosis of NLS. After birth, radiological imaging did not detect any gross bone abnormalities. DNA was extracted from fetal and parental peripheral blood, all coding exons of PHGDH were PCR-amplified and subjected to Sanger sequencing. Sequencing of PHGDH identified a homozygous premature stop codon mutation (c.1297C>T; p.Gln433*) in fetal DNA, both parents (first-cousins) being heterozygotes. Based on previous associations of mutations in this gene with a milder NLS phenotype, as well as cases of serine deficiency, these observations lend further support to a genotype-phenotype correlation between the degree of PHGDH inactivation and disease severity.

A case of the Neu-Laxova syndrome

Neu-Laxova syndrome is a rare lethal genetic disorder characterized by multiple congenital abnormalities, microcephaly and ichthyosiform skin lesions. The authors describe a case of this syndrome in a newborn baby.

A spectrum of phenotypical expression OF Neu-Laxova syndrome: Three case reports and a review of the literature

Neu-Laxova syndrome is a rare autosomal recessive disorder characterized by severe intra-uterine growth restriction, extreme microcephaly, marked edema with skin restriction, ichthyosis, craniofacial anomalies, limb deformities, and a spectrum of central nervous system malformations. Less than 70 cases have been described since the first report in 1971. To this day the etiology and genetic basis remains unknown. Consanguinity has been reported. Some authors have postulated the syndrome to be a form of neuro-ectodermal dysplasia, while others suggest that it is a malformation syndrome secondary to severe skin restriction. Although the outcome of this syndrome is lethal, a single case of longer survival (6 months) has been reported. The majority of cases are stillborn or die shortly after birth. Thus, it is clear that Neu-Laxova exhibits a spectrum of disease, with varying degrees of phenotypic expression. We are presenting three new cases of Neu-Laxova syndrome; two were stillbirths and one lived for eleven weeks. Our microscopic and post-mortem findings in these three cases display the vast spectrum of this rare syndrome.

Neu-Laxova syndrome, grossly appearing normal on 20 weeks ultrasonographic scan, that manifested late in pregnancy: a case report

INTRODUCTION

Neu-Laxova syndrome (NLS) is a very rare and extremely lethal syndrome almost always inherited by autosomal recessive pattern.

CASE PRESENTATION

A 21-year-old G2 P1 L0 Turkish woman was first seen at 18 weeks of gestation in antenatal policlinic. On ultrasound examination performed at 20 weeks of gestation for excluding gross abnormalities showed no abnormality and biometry of the fetus was concordant with date of gestation. She stopped follow-up after then. The woman were presented to emergency unit with a complaint of absent fetal movements at 38 weeks of gestation. Multiple abnormalities consistent with NLS have been seen on sonography. Nonvisible gastric cavity was also seen on sonography. Postmortem examination by genetics specialists confirmed the diagnosis of NLS.

CONCLUSION

Neu-Laxova syndrome must be monitored continuously from the beginning of gestation to third trimester via serial ultrasonographies that is focused on previously described features of syndrome especially for consanguineous couples with or without a previous affected fetus.

A rare cause of polyhydramnios: Neu-Laxova syndrome

Neu-Laxova syndrome is a rare group of congenital malformations including intrauterine growth retardation (IUGR), microcephaly, central nervous system alterations, facial abnormalities, ichthyosis, limb abnormalities, generalized edema, polyhydramnios, and perinatal death. Thirty cases have been identified since the publication of the first two cases and only five of them had a prenatal diagnosis. The earliest diagnosis in a published case was at week 32 of gestation. This study illustrates that the detection of the syndrome during the second trimester of gestation is possible, with emphasis on the detection of the early appearance of polyhydramnios and the association of the syndrome with the Arabic ethnic group.

Neu-Laxova syndrome: detailed prenatal diagnostic and post-mortem findings and literature review

Neu-Laxova syndrome (NLS) is a lethal, autosomal recessive multiple malformation syndrome with many features resulting from severe skin restriction and decreased fetal movement. It is characterized by ichthyosis, marked intrauterine growth restriction (IUGR), microcephaly, short neck, central nervous system (CNS) anomalies, limb deformities, hypoplastic lungs, edema, and abnormal facial features including severe proptosis with ectropion, hypertelorism, micrognathia, flattened nose, and malformed ears. We present two new patients with NLS with striking prenatal diagnostic findings and detailed post-mortem examinations and review the previously described cases in the literature. Data from these patients suggest that the NLS represents a heterogeneous phenotype. Prenatal ultrasound findings of marked ocular proptosis in a growth restricted, edematous fetus should prompt consideration of a diagnosis of the NLS.

Second trimester diagnosis of Neu Laxova syndrome

This is the first report of a prenatally diagnosed case of Neu Laxova syndrome (NLS) from India. This also includes a case of NLS in monochorionic diamniotic twins and two more cases in which we were able to detect most of the features of NLS as early as 19 to 20 weeks by routine antenatal ultrasonography. Severe intrauterine growth retardation (IUGR), microcephaly, central nervous system (CNS) abnormality, joint contractures, and abnormal facies are the major diagnostic features observed in prenatal ultrasonography. Risk factors such as consanguinity and history of intrauterine death or stillbirth in siblings have been noted in all the cases, but none of the three families that were reported had previously had an affected fetus. The spectrum of skin manifestations and frequency of occurrence of major clinical features of the syndrome have been discussed. Review of the literature on NLS and possibility of detecting the syndrome in the second trimester is discussed.

Cerebro-osseous-digital syndrome: four new cases of a lethal skeletal dysplasia--distinct from Neu-Laxova Syndrome

Neu-Laxova Syndrome (NLS) is a severe disorder with intrauterine growth retardation, edema, and characteristic face (including microcephaly with receding forehead, protuberant eyes, a flattened nose, deformed ears, cleft palate, and micrognathia). Ichthyosis is often present. Limb anomalies include hypoplastic fingers and syndactyly of fingers and toes. Patients are usually stillborn or die shortly after birth. We report five unrelated patients--four with atypical NLS and one with typical NLS. All five patients were stillbirths. Clinically, the atypical NLS patients showed a large skull; rhizo-, meso-, and acromelia; and hypoplasia of the metacarpals and phalanges. The feet were similarly affected. Radiographically, the atypical patients showed interpediculate narrowing and hypoplastic vertebral bodies. The long bones were stick-like, showing diaphyseal widening that spared the metaphyses and was more pronounced in the lower extremities. The ilia had a half-moon configuration with widening of the sacrosciatic notches. The ischia were vertical and the pubic bone was absent. The typical NLS patient showed microcephaly, normal vertebral body, and long bone ossification, but a pelvic configuration similar to that of the atypical NLS patients. The common and distinguishing clinical and radiographic features are reviewed. Scott et al. [1981: Am J Med Genet 9:165-175] described two patients with NLS with radiographic and clinical findings similar to patients 1-4 reported here. Patients 1-4 of this report lack the typical findings of NLS and likely represent a distinct lethal skeletal dysplasia.

COFS syndrome with familial 1;16 translocation

We report on an Egyptian girl with phenotypic abnormalities of cerebro-oculofacio-skeletal syndrome. She had microcephaly, bilateral congenital cataract, nystagmus, long ear pinnae, camptodactyly, prominent heels, coxa valga, kyphosis and flexure contracture of the elbows and knees. CT scan showed bilateral symmetrical intracranial calcifications. In addition, she had an apparently balanced translocation: 46,XX,t(1;16)(q23;q13) in all cells transmitted from a phenotypically normal mother with a similar balanced translocation mosaicism. We suggest that genes for COFS syndrome could be located on chromosome 1q23 or 16q13. We recommend chromosomal analysis and DNA studies in cases with COFS manifestations.

Neu-Laxova syndrome: pathological evaluation of a fetus and review of the literature

Neu-Laxova syndrome is a rare autosomal recessive disorder characterized by ichthyosis, intrauterine growth retardation, microcephaly, short neck, central nervous system abnormalities, hypoplastic or atelectatic lungs, limb deformities, edema, polyhydramnios, and short umbilical cord. Abnormal facial features include sloping forehead, hypertelorism, severe ectropion, proptosis, malformed ears, flat nose, and micrognathia. A necropsy study of a male infant with Neu-Laxova syndrome is described. Cleft palate and ambiguous external genitalia were present in addition to anomalies characteristic of Neu-Laxova syndrome. The clinical manifestations are compared with those of the 40 previously reported cases.

Neu-Laxova syndrome: report of a case from Turkey

We describe a case of Neu-Laxova syndrome in a newborn female who was born at full-term to consanguineous Turkish parents. The pathological and radiological features are described.