Prenatal diagnosis of X-linked hydrocephalus in a Chinese family with four successive affected pregnancies

The genetic basis of hydrocephalus: genes, pathways, mechanisms, and global impact

Hydrocephalus (HC) is a heterogenous disease characterized by alterations in cerebrospinal fluid (CSF) dynamics that may cause increased intracranial pressure. HC is a component of a wide array of genetic syndromes as well as a secondary consequence of brain injury (intraventricular hemorrhage (IVH), infection, etc.) that can present across the age spectrum, highlighting the phenotypic heterogeneity of the disease. Surgical treatments include ventricular shunting and endoscopic third ventriculostomy with or without choroid plexus cauterization, both of which are prone to failure, and no effective pharmacologic treatments for HC have been developed. Thus, there is an urgent need to understand the genetic architecture and molecular pathogenesis of HC. Without this knowledge, the development of preventive, diagnostic, and therapeutic measures is impeded. However, the genetics of HC is extraordinarily complex, based on studies of varying size, scope, and rigor. This review serves to provide a comprehensive overview of genes, pathways, mechanisms, and global impact of genetics contributing to all etiologies of HC in humans.

Adducted Thumb in the First Trimester of Pregnancy: An Early Clue to Prenatal Diagnosis of L1 Syndrome

A pregnant woman was revealed to have an unusual position of the fetal hand by a routine 12-week ultrasound. Bilateral adducted thumbs and a male phenotype were confirmed by another ultrasound at 14 weeks' gestation. A structural survey at 18 weeks revealed fetal hydrocephalus with severe bilateral ventriculomegaly. The pregnancy was terminated, and postnatal examination with trio exome sequencing detected a hemizygous deletion (1,511 bp in size) variant of L1CAM gene in the fetus, inherited from the mother. The fetus was diagnosed as L1 syndrome (X-linked hydrocephalus). A family study found that this was a familial mutant allele. This study demonstrates that fetal hand abnormalities can be identified in the first trimester. Adducted thumbs might indicate the maldevelopment of the fetal brain, and therefore, examination of fetal hands and fingers should be integrated into fetal anomaly scans.

X-linked hydrocephalus masquerading as spina bifida and destructive porencephaly in successive generations in one family

The authors report a case of X-linked hydrocephalus which presented as a destructive porencephaly. There was asymmetric dilatation of the ventricles of prenatal onset, and neuro-imagining studies were suggestive of infection or haemorrhage. The child was profoundly handicapped but did not have adducted thumbs. Two of his mother's brothers had been stillborn, and postmortem reports revealed that the diagnosis had been isolated hydrocephalus and not spina bifida as reported by the family. Despite serial ultrasound scans, recurrence of X-linked hydrocephalus in the mother's subsequent pregnancy was not detected until 26 weeks gestation, when the ventricles became grossly dilated. The diagnosis was confirmed in this family by identification of a mutation within the LICAM gene.

X-linked hydrocephalus masquerading as spina bifida and destructive porencephaly in successive generations in one family

The authors report a case of X-linked hydrocephalus which presented as a destructive porencephaly. There was asymmetric dilatation of the ventricles of prenatal onset, and neuro-imagining studies were suggestive of infection or haemorrhage. The child was profoundly handicapped but did not have adducted thumbs. Two of his mother's brothers had been stillborn, and postmortem reports revealed that the diagnosis had been isolated hydrocephalus and not spina bifida as reported by the family. Despite serial ultrasound scans, recurrence of X-linked hydrocephalus in the mother's subsequent pregnancy was not detected until 26 weeks gestation, when the ventricles became grossly dilated. The diagnosis was confirmed in this family by identification of mutation within the L1CAM gene.