Early second trimester prenatal diagnosis of Neu-Laxova syndrome

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 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.

[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.

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.

Prenatal diagnosis and postmortem findings of Neu-laxova syndrome

Neu-laxova syndrome is a lethal, autosomal recessive condition associated with ectodermal abnormalities and other characteristic features, including microcephaly, marked intrauterine growth restriction, limb deformities, central nervous system malformations and abnormal facial features, consisting of severe proptosis with ectropion, hypertelorism, micrognathia, flattened nose, malformed ears, and gaping mouth. Here we present a fetus having a dysmorphic face with proptotic eyes, retracted eye lids, depressed nasal bridge and micrognathia at 25 weeks of gestation. The extremities were contracted and no fetal movements were observed during the ultrasonographic examination. The fetus also had microcephaly and the amniotic fluid was increased. The pregnancy was terminated and the abnormalities demonstrated on prenatal ultrasound were confirmed at autopsy.

Evaluation of a Fetus with Neu-Laxova Syndrome through Prenatal, Clinical, and Pathological Findings

We report a case of Neu-Laxova syndrome in a fetus at 22 weeks with the ultrasonographic findings of characteristic facial findings, limb contractures, kyphosis and polyhydramnios. Pathological and ultrasonographic studies are discussed.

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.