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

Putting It All Together: Postmortem Diagnosis of a Rare Ichthyosis Syndrome

Neu-Laxova syndrome (NLS) is a rare lethal disorder with autosomal recessive inheritance and is characterized by multiple congenital anomalies. Our case of NLS presented with severe intrauterine growth restriction (IUGR), abnormal facial features, severe central nervous system malformations, skeletal muscle contractures, and the hallmark signs of NLS: ichthyotic skin and excessive subcutaneous tissue with edema. Additionally, testing amniotic fluid from a prior pregnancy with a fetus showing similar abnormalities revealed several regions of homozygosity; one of these regions involved chromosome 1p13.2-p11.2, where the PHGDH gene is located. Based on the pattern of findings on serial fetal ultrasounds, postmortem neonatal exams, gross and microscopic exams, radiographs, and genetic analysis in conjunction with the clinical history and the prior pregnancy with the above-described molecular alteration, a final diagnosis of NLS was made. This rare developmental disorder is characterized by heterogenous neuroectodermal defects. Fetal ultrasound in the second trimester can help diagnose it. It is postulated to be caused by loss-of-function mutations in the PHGDH (phosphoglycerate dehydrogenase), PSAT1 (phosphoserine aminotransferase 1), and PSPH (phosphoserine phosphatase) genes, which are responsible for de novo L-serine synthesis.

Expanding the genotypic and phenotypic spectrum of severe serine biosynthesis disorders

Serine biosynthesis disorders comprise a spectrum of very rare autosomal recessive inborn errors of metabolism with wide phenotypic variability. Neu-Laxova syndrome represents the most severe expression and is characterized by multiple congenital anomalies and pre- or perinatal lethality. Here, we present the mutation spectrum and a detailed phenotypic analysis in 15 unrelated families with severe types of serine biosynthesis disorders. We identified likely disease-causing variants in the PHGDH and PSAT1 genes, several of which have not been reported previously. Phenotype analysis and a comprehensive review of the literature corroborates the evidence that serine biosynthesis disorders represent a continuum with varying degrees of phenotypic expression and suggest that even gradual differences at the severe end of the spectrum may be correlated with particular genotypes. We postulate that the individual residual enzyme activity of mutant proteins is the major determinant of the phenotypic variability, but further functional studies are needed to explore effects at the enzyme protein level.

Clinical, molecular, and pathological findings in a Neu-Laxova syndrome stillborn: A Brazilian case report

Neu-Laxova syndrome (NLS) is a lethal genetic multiple congenital anomaly syndrome of unknown prevalence representing the severe spectrum of serine biosynthesis defects associated with PHGDH, PSAT1, or PSP gene mutations. The purpose of this study was to describe clinical/molecular and pathologic features of a NLS case caused by novel heterozygous missense variant in PHGDH gene identified in his consanguineous parents.

Neu-Laxova syndrome presenting prenatally with increased nuchal translucency and cystic hygroma: The utility of exome sequencing in deciphering the diagnosis

Neu-Laxova syndrome (NLS) is a lethal autosomal recessive microcephaly syndrome associated with intrauterine growth restriction (IUGR) and multiple congenital anomalies. Clinical features include central nervous system malformations, joint contractures, ichthyosis, edema, and dysmorphic facial features. Biallelic pathogenic variants in either the PHGDH or PSAT1 genes have been shown to cause NLS. Using exome sequencing, we aimed to identify the underlying genetic diagnosis in three fetuses (from one family) with prenatal skin edema, severe IUGR, micrognathia, renal anomalies, and arthrogryposis and identified a homozygous c.1A>C (p.Met1?, NM_006623.3) variant in the PHGDH gene. Loss of the translation start codon is a novel genetic mechanism for the development of NLS. Prenatal diagnosis of NLS is challenging and few reports describe the fetal pathology. Fetal neuropathologic examination revealed: delayed brain development, congenital agenesis of the corticospinal tracts, and hypoplasia of the hippocampus, cerebellum and brainstem. Each pregnancy also showed increased nuchal translucency (NT) or cystic hygroma. While NLS is rare, it may be a cause of recurrent increased NT/cystic hygroma. This finding provides further support that cystic hygroma has many different genetic causes and that exome sequencing may shed light on the underlying genetic diagnoses in this group of prenatal patients.

Etiologies of uterine malformations

Ranging from aplastic uterus (including Mayer-Rokitansky-Kuster-Hauser syndrome) to incomplete septate uterus, uterine malformations as a group are relatively frequent in the general population. Specific causes remain largely unknown. Although most occurrences ostensibly seem sporadic, familial recurrences have been observed, which strongly implicate genetic factors. Through the study of animal models, human syndromes, and structural chromosomal variation, several candidate genes have been proposed and subsequently tested with targeted methods in series of individuals with isolated, non-isolated, or syndromic uterine malformations. To date, a few genes have garnered strong evidence of causality, mainly in syndromic presentations (HNF1B, WNT4, WNT7A, HOXA13). Sequencing of candidate genes in series of individuals with isolated uterine abnormalities has been able to suggest an association for several genes, but confirmation of a strong causative effect is still lacking for the majority of them. We review the current state of knowledge about the developmental origins of uterine malformations, with a focus on the genetic variants that have been implicated or associated with these conditions in humans, and we discuss potential reasons for the high rate of negative results. The evidence for various environmental and epigenetic factors is also reviewed. © 2016 Wiley Periodicals, Inc.

Pathology of the stillborn infant for the general pathologist: part 2

As the information obtained from previable fetal and stillbirth autopsies is used not only to explain the loss to the parents, but for future pregnancy planning, general pathologists need to be comfortable in dealing with these autopsies. The importance of an adequate fetal examination has been emphasized in a recent policy on the subject by the American Board of Pathology http://www.abpath.org/FetalAutopsyPoli'cy.pdf. This second review paper covers the approach to hydrops fetalis. The approach to the nonanomalous and anomalous fetus was covered in the first part of this series.

A collodion baby with facial dysmorphism, limb anomalies, pachygyria and genital hypoplasia: a mild form of Neu-laxova syndrome or a new entity?

Neu-Laxova syndrome is a rare, lethal, autosomal recessive disorder characterized by intrauterine growth retardation, central nervous system anomalies, skin findings, such as ichthyosis, edema, collodion baby and harlequin fetus, facial dysmorphic features, limb anomalies and genital hypoplasia. Although it is generally a lethal condition, cases of such patients who lived beyond 6 months and 10 months of age have been reported. Here, we describe an 8-year-old boy who was born with collodion membrane, facial dysmorphic features, limb anomalies, genital hypoplasia and pachygyria. He had no major health problems over the course of 8 years of follow-up, except for mild mental/motor retardation, ichthyosis, facial dysmorphic features and limb anomalies. Based on these features, we suggest that because Neu-Laxova syndrome represents a heterogeneous phenotype, our case may be a milder variant of this syndrome or a new genetic entity.

Anesthetic management of three pediatric cases with Pena-Shokeir syndrome

Pena-Shokeir syndrome is a rare, early lethal disease. It is characterized by fetal growth restriction; craniofacial deformities, for example micrognathia and microcephaly; multiple ankyloses; and pulmonary hypoplasia. For patients with this syndrome, maintenance of airway and control of perioperative respiratory complications are important for anesthetic management. We report 3 pediatric cases of Pena-Shokeir syndrome undergoing tracheostomy and arthrolysis under general anesthesia using sevoflurane, nitrous oxide, fentanyl, and vecuronium bromide. Anesthetic procedures including mask ventilation, tracheal intubation, and extubation were successfully performed without complications during and after surgery. In patients with Pena-Shokeir syndrome, inhalational anesthetics can be safely used for induction and maintenance of anesthesia, although it is important to assume that difficult airway management might be encountered.

Rare manifestations of Neu-Laxova syndrome

Neu-Laxova syndrome is a rare lethal congenital disorder involving multiple systems. Intrauterine growth retardation, ichthyosis, microcephaly, abnormal facial findings and limb contractures are its key features. We present a stillborn female baby of 1.5 kg with characteristic features including growth retardation, microcephaly, severe ectropion, micrognathia, flattened nose, eclabion, large ears, puffy hands and feet. In addition to these features, lissencephaly, severely hypoplastic cerebrum and corpus callossum, Dandy-Walker malformation, Transposition of Great Vessels and hepatomegaly were noted at autopsy. The patient was born at 38 weeks of gestation to consanguineous (second degree) Indian parents. The mother was 26 year old second gravida with lack of prenatal followup. Therefore, the condition was diagnosed postnatally. Because of the autosomal recessive inheritence of Neu-Laxova syndrome, in countries with high rates of consanguineous marriage, serial prenatal ultrasound examinations with genetic counseling should be performed on pregnant women at high risk to offer termination of affected pregnancies.