Two new Brazilian patients with Gómez-López-Hernández syndrome: reviewing the expanded phenotype with molecular insights

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.

Clinical and molecular evaluation of 13 Brazilian patients with Gomez-López-Hernández syndrome

We aim to characterize patients with Gomez-López-Hernández syndrome (GLHS) clinically and to investigate them molecularly. A clinical protocol, including a morphological and neuropsychological assessment, was applied to 13 patients with GLHS. Single-nucleotide polymorphism (SNP) array and whole-exome sequencing were undertaken; magnetic resonance imaging was performed in 12 patients, including high-resolution, heavily T2-weighted sequences (HRT2) in 6 patients to analyze the trigeminal nerves. All patients presented alopecia; two did not present rhombencephalosynapsis (RES); trigeminal anesthesia was present in 5 of the 11 patients (45.4%); brachycephaly/brachyturricephaly and mid-face retrusion were found in 84.6 and 92.3% of the patients, respectively. One patient had intellectual disability. HRT2 sequences showed trigeminal nerve hypoplasia in four of the six patients; all four had clinical signs of trigeminal anesthesia. No common candidate gene was found to explain GLHS phenotype. RES does not seem to be an obligatory finding in respect of GLHS diagnosis. We propose that a diagnosis of GLHS should be considered in patients with at least two of the following criteria: focal non-scarring alopecia, rhombencephalosynapsis, craniofacial anomalies (brachyturrycephaly, brachycephaly or mid-face retrusion), trigeminal anesthesia or anatomic abnormalities of the trigeminal nerve. Studies focusing on germline whole genome sequencing or DNA and/or RNA sequencing of the alopecia tissue may be the next step for the better understanding of GLHS etiology.

Rhombencephalosynapsis: Fused cerebellum, confused geneticists

Rhombencephalosynapsis (RES) is a unique cerebellar malformation characterized by fusion of the cerebellar hemispheres with partial or complete absence of a recognizable cerebellar vermis. Subsets of patients also have other brain malformations such as midbrain fusion with aqueductal stenosis, characteristic craniofacial features (prominent forehead, flat midface, hypertelorism, ear abnormalities), and somatic malformations (heart, kidney, spine, and limb defects). Similar to known genetic brain malformations, the RES cerebellar malformation is highly stereotyped, yet no genetic causes have been identified. Here, we outline our current understanding of the genetic basis for RES, discuss limitations, and outline future approaches to identifying the causes of this fascinating brain malformation.

Co-occurrence of Gomez-Lopez-Hernandez syndrome and Autism Spectrum Disorder: Case report with review of literature

We report on Gomez-Lopez-Hernandez syndrome (GLHS) in a Caucasian patient, Georgian, 36 months, male, only child born to non-consanguineous parents. There were no similar cases in the family and among close relatives. MRI study confirmed rhombencephalosynapsis (fusion of cerebellar hemispheres in combination with the agenesis of cerebellar vermis) and mild dilation of the lateral ventricles. Other main findings are bilateral parieto-temporal alopecia and brachiturricephaly (broad skull shape and tower-like elongation of the cranium in the vertical axis), low-set posteriorly retracted ears, strabismus (in the right eye), hypotonia (Beighton scale score - 6) and ataxia (trouble maintaining balance). Patient has no signs of trigeminal anesthesia, no recurrent, painless eye infections, corneal opacities and ulcerated wounds on the facial skin and buccal mucosa were observed. Based on the scientific literature we suggest a finding of brachiturricephaly in addition to rhombencephalosynapsis and bilateral alopecia sufficient to put a diagnosis of GLHS. Patient did not speak, disregarded guardians and clinician addressing him, did not make eye contact, was restless and occasionally displayed aggression and self-injurious behavior. These symptoms confirm the earlier diagnosis of Autism Spectrum Disorder (ASD). Therefore, the current study describes a case of co-occurrence of GLHS and ASD.

Gomez-Lopez-Hernández syndrome: First reported case from the Indian subcontinent

Gomez-Lopez-Hernández syndrome (GLHS) is a rare neurocutaneous syndrome characterized by a triad of findings: partial alopecia of the scalp, trigeminal anaesthesia, and rhombencephalosynapsis. GLHS is also known as cerebello-trigeminal-dermal dysplasia. Besides this triad, a number of varying traits have been described in 35 previously reported cases. Reported here is a case of a four-year-old boy, born out of consanguineous marriage, presenting with the classic triad of findings, i.e. partial alopecia of the scalp, trigeminal anaesthesia, and rhombencephalosynapsis. To the extent known, this is the first case of GLHS reported from India. If a child presents with alopecia and rhom-bencephalosynapsis, GLHS should be considered in the differential diagnosis. A host of studies can be used to determine the exact pathogenesis, and confirming the diagnosis of GLHS is an important step in prenatal testing for at-risk pregnancies.

Gómez-López-Hernández Syndrome: A Rare Cause of Bilateral Nonscarring Alopecia

Gómez-López-Hernández syndrome is a rare neurocutaneous disorder characterized by the triad of rhombencephalosynapsis, parietal alopecia, and trigeminal anesthesia. We report a 16-year-old girl with bilateral parietotemporal alopecia in whom cranial magnetic resonance imaging revealed rhombencephalosynapsis, suggesting a diagnosis of Gómez-López-Hernández syndrome. Neurologic examination and neuroimaging may be warranted in select patients with parietal alopecia to exclude this uncommon entity.

Gómez-López-Hernández syndrome in a Japanese patient: a case report

Gómez-López-Hernández syndrome (GLHS) is a rare neurocutaneous syndrome characterized by the triad of rhombencephalosynapsis, trigeminal anesthesia, and bilateral parieto-occipital alopecia. We herein describe the first Japanese patient with GLHS characterized by the standard triad with typical craniofacial anomaly including hypertelorism, brachyturricephaly and midface retrusion, and a short stature. This female patient had also exhibited fever-induced convulsive seizures and psychomotor developmental delay since infancy. Brain magnetic resonance imaging showed severe rhombencephalosynapsis, supratentorial abnormalities (aplasia of the septum pellucidum, severe ventricular enlargement, and hypoplasia of the corpus callosum), and hippocampus atrophy. Bilateral ectopic cerebellums were also observed. This report describes the long-term clinical outcome of GLHS and a new neuroradiological finding regarding rhombencephalosynapsis.

Gómez-López-Hernández syndrome in a child born to consanguineous parents: new evidence for an autosomal-recessive pattern of inheritance?

BACKGROUND

Gómez-López-Hernández syndrome is a rare genetic disease characterized by scalp alopecia with trigeminal anesthesia, brachycephaly or turribrachycephaly, midface retrusion, and rhombencephalosynapsis. We report the second case with this condition who presented with consanguineous parents.

PATIENT

This boy was evaluated shortly after birth because of suspected craniosynostosis. He was the only son of healthy, consanguineous parents (his maternal grandmother and his paternal great-grandfather were siblings). His examination was notable for turribrachycephaly, prominent forehead, bilateral parietotemporal alopecia, midfacial retrusion, anteverted nostrils, micrognathia, low-set and posteriorly rotated ears, and short neck with redundant skin. Radiographs and tridimensional computed tomography scan of skull revealed lambdoid craniosynostosis. Brain magnetic resonance imaging revealed complete rhombencephalosynapsis, aqueductal stenosis, fused colliculi, abnormal superior cerebellar penducle, mild ventriculomegaly, and dysgenesis of the corpus callosum.

CONCLUSIONS

Since its first description, 34 patients with this condition have been reported. The etiology of Gómez-López-Hernández syndrome is unknown. However, it is noteworthy that the patient in this report presented with a family history of consanguinity because this finding reinforces the possibility of an autosomal-recessive inheritance for this condition.

Beyond Gómez-López-Hernández syndrome: recurring phenotypic themes in rhombencephalosynapsis

Rhombencephalosynapsis (RES) is an uncommon cerebellar malformation characterized by fusion of the hemispheres without an intervening vermis. Frequently described in association with Gómez-López-Hernández syndrome, RES also occurs in conjunction with VACTERL features and with holoprosencephaly (HPE). We sought to determine the full phenotypic spectrum of RES in a large cohort of patients. Information was obtained through database review, patient questionnaire, radiographic, and morphologic assessment, and statistical analysis. We assessed 53 patients. Thirty-three had alopecia, 3 had trigeminal anesthesia, 14 had VACTERL features, and 2 had HPE with aventriculy. Specific craniofacial features were seen throughout the cohort, but were more common in patients with alopecia. We noted substantial overlap between groups. We conclude that although some distinct subgroups can be delineated, the overlapping features seen in our cohort suggest an underlying spectrum of RES-associated malformations rather than a collection of discrete syndromes.

Rhombencephalosynapsis: a hindbrain malformation associated with incomplete separation of midbrain and forebrain, hydrocephalus and a broad spectrum of severity

Rhombencephalosynapsis is a midline brain malformation characterized by missing cerebellar vermis with apparent fusion of the cerebellar hemispheres. Rhombencephalosynapsis can be seen in isolation or together with other central nervous system and extra-central nervous system malformations. Gómez-López-Hernández syndrome combines rhombencephalosynapsis with parietal/temporal alopecia and sometimes trigeminal anaesthesia, towering skull shape and dysmorphic features. Rhombencephalosynapsis can also be seen in patients with features of vertebral anomalies, anal atresia, cardiovascular anomalies, trachea-oesophageal fistula, renal anomalies, limb defects (VACTERL) association. Based on a comprehensive evaluation of neuroimaging findings in 42 patients with rhombencephalosynapsis, we propose a spectrum of severity, ranging from mild (the partial absence of nodulus, anterior and posterior vermis), to moderate (the absence of posterior vermis with some anterior vermis and nodulus present), to severe (the absence of posterior and anterior vermis with some nodulus present), to complete (the absence of the entire vermis including nodulus). We demonstrate that the severity of rhombencephalosynapsis correlates with fusion of the tonsils, as well as midbrain abnormalities including aqueductal stenosis and midline fusion of the tectum. Rhombencephalosynapsis is also associated with multiple forebrain abnormalities including absent olfactory bulbs, dysgenesis of the corpus callosum, absent septum pellucidum and, in rare patients, atypical forms of holoprosencephaly. The frequent association between rhombencephalosynapsis and aqueductal stenosis prompted us to evaluate brain magnetic resonance images in other patients with aqueductal stenosis at our institution, and remarkably, we identified rhombencephalosynapsis in 9%. Strikingly, subjects with more severe rhombencephalosynapsis have more severely abnormal neurodevelopmental outcome, as do subjects with holoprosencephaly and patients with VACTERL features. In summary, our data provide improved diagnostic and prognostic information, and support disruption of dorsal-ventral patterning as a mechanism underlying rhombencephalosynapsis.

Gómez-López-Hernández syndrome: reappraisal of the diagnostic criteria

Gómez-López-Hernández syndrome (GLHS) is a rare and possibly underdiagnosed condition. So far, 21 patients have been reported and all of them were sporadic observations. We report six additional patients. The hallmark triad of GLHS, also named cerebellotrigeminal dermal dysplasia, consists of rhombencephalosynapsis, trigeminal anesthesia (often giving rise to corneal opacities), and bilateral parietal or parieto-occipital alopecia. Our patients had rhombencephalosynapsis and alopecia, but none had trigeminal dysfunction. In this respect, the term cerebellotrigeminal dermal dysplasia is potentially misleading. In conclusion, only rhombencephalosynapsis and alopecia are consistently present in GLHS and are required diagnostic criteria, while trigeminal anesthesia, dysmorphic features, and ataxia are inconsistent findings. A high index of suspicion is required to diagnose GLHS, particularly as alopecia tends to be hidden by surrounding scalp hair.

Truncal ataxia, hypotonia, and motor delay with isolated rhombencephalosynapsis

We report on a 16-month-old girl with developmental motor delay, microcephaly, and mild truncal ataxia who was revealed to have rhombencephalosynapsis on magnetic resonance imaging. The child was nonsyndromic and exhibited normal cognitive and social abilities for her age, despite neuroimaging findings. As this case demonstrates, motor skills in children with isolated rhombencephalosynapsis may be relatively mildly affected, and cognition may be normal despite the presence of a major central nervous system anomaly. Neuroimaging may be helpful in defining the nature of a child's deficits at an early age, particularly when associated with microcephaly and abnormalities on neurologic examination.

Gomez-Lopez-Hernandez syndrome: two new cases and review of the literature

Gomez-Lopez-Hernandez syndrome, or cerebellotrigeminal-dermal dysplasia, is a rare neurocutaneous syndrome of trigeminal anesthesia, scalp alopecia and cerebellar anomalies. Other features include craniosynostosis, short stature, hypertelorism, down-slanting palpebral fissures, corneal opacities, mediofacial hypoplasia, and turri-brachycephaly. There have been 19 cases documented to date and we report on two additional male patients, 1 and 6 years of age, with typical features, mild mental retardation and dyspraxia. In both cases, MRI findings included rhombencephalosynapsis, a constant neuroimaging feature in this syndrome, comprising fusion of the cerebellar hemispheres with agenesis of the cerebellar vermis. Based on literature and our experience, we propose the presence of trigeminal anesthesia and/or partial alopecia of the scalp to complete the diagnosis of the syndrome.