Skeletal syndromes and dysplasias include more than 150 entities, most often of genetic origin. Some of them cause abnormalities in the cervical spine, with or without instability, distortion or compression of the spinal cord. These abnormalities must be detected and treated if necessary because they can have serious consequences such as quadriplegia. Up to 30% of patients with Down syndrome are affected by occipitocervical or atlantoaxial instability. Dynamic cervical spine radiographs are the most common screening tool. Mucopolysaccharidoses (MPS) are a group of inherited lysosomal storage diseases that result in the accumulation of glycosaminoglycans sometimes responsible for craniocervical instability and cervical spinal canal stenosis. Their monitoring requires an MRI every two years. Neurofibromatosis type 1 and syndromes with connective tissue abnormalities (Marfan syndrome, Loeys-Dietz syndrome, Ehlers-Danlos syndrome) can cause severe and unstable cervical spine deformities that may remain asymptomatic for a long time. Cervical X-rays should therefore be performed if there is the slightest doubt. Some rare chondrodysplasias (punctate chondrodysplasia, Larsen syndrome, Metatropic dysplasia) or segmentation anomalies (Klippel Feil syndrome, Sprengel's disease) have cervical spine abnormalities that should be looked for. In case of progression of a deformity (usually kyphosis) or stenosis of the cervical spine, it is important to consider surgical treatment with correction and stabilization. Sometimes preceded by a period of Halo traction, the instrumentation must have "wide" limits and exceed the anatomical limits of the spinal deformity by at least 2-3 levels to prevent the development of an adjacent deformity. The increasing use of surgical navigation techniques allows for greater corrections and more efficient stabilizations, including severe cervical spinal deformities. Vigilance and the detection of these abnormalities remain the key to early and preventive treatment of the complications of these spinal anomalies on often difficult terrain. LEVEL OF EVIDENCE: >V (expert opinion).

The Collagen Type 4 alpha 1 (COL4A1), is an important component of nearly all vascular basement membranes. Pathogenic mutation of this gene results in varied manifestations. In this report, we describe a two-and-a-half-year-old boy with an eventful perinatal period, global developmental delay, and epileptic spasms. Examination revealed microcephaly, nystagmus, and spasticity in limbs. Electroencephalogram showed multifocal epileptiform discharges and MRI brain demonstrated periventricular white matter changes, intracerebral bleeds, and porencephalic cysts. CT brain showed intracranial calcifications and screening for congenital infection was negative. The molecular genetic evaluation was later confirmed with a heterozygous mutation of the COL4A1 gene on exon 37 (variant - p.Gly1050Ala) with an autosomal dominant inheritance pattern. Currently, the child has developed drug-refractory epilepsy requiring polypharmacy and the ketogenic diet. COL4A1 gene mutations are close mimickers of Cerebral Palsy, hence a high index of suspicion should be exercised while approaching a child with spastic quadriplegia in order to promptly diagnose and manage such children for a better neurological outcome.

Asparagine synthetase deficiency (ASNSD) is a rare congenital disorder characterized by severe progressive microcephaly, global developmental delay, spastic quadriplegia, and refractory seizures. ASNSD is caused by variations of the ASNS gene. The present study showed a Chinese family with a fetus suffering microcephaly. Whole-exome sequencing and Sanger sequencing were used to identify the disease-associated genetic variants. Compound heterozygous variants c.97C>T p. (R33C) and c.1031-2_1033del were identified in the ASNS gene and the variants were inherited from the parents. The mutation site c.97C>T was highly conserved across a wide range of species and predicted to alter the local electrostatic potential. The variant c.1031-2_1033del was classified pathogenic. However, there is no case report of prenatal diagnosis of ASNSD. This is the first description of fetal compound mutations in the ASNS gene leading to ASNSD, which expanded the spectrum of ASNSD. Serine deficiency disorders include a spectrum of disease ranging from lethal prenatal-onset Neu-Laxova syndrome to serine deficiency with infantile, juvenile, or adult onset. Neu-Laxova syndrome is characterized by severe intrauterine growth deficiency, microcephaly, congenital bilateral cataracts, characteristic dysmorphic features, limb anomalies, and collodion-like ichthyosis. Infants are typically stillborn or die in early infancy. Infantile-onset serine deficiency is characterized by seizures, microcephaly, developmental delay, intellectual disability, and spastic quadriplegia. Individuals that present with juvenile-onset serine deficiency have seizures and many develop spastic quadriplegia. Adult-onset serine deficiency is characterized by progressive axonal polyneuropathy with ataxia and possible cognitive impairment. The diagnosis of a serine deficiency disorder is established in a proband with biallelic pathogenic variants in PHGDH, PSAT1, or PSPH identified by molecular genetic testing. Targeted therapy: Early treatment with L-serine supplementation; glycine supplementation with L-serine has been used in some individuals. Supportive care: L-serine therapy is more effective than anti-seizure medication for treatment of seizures; developmental and educational support; feeding therapy for persistent feeding issues; treatment of cataracts per ophthalmologist; standard treatments for spasticity and polyneuropathy; preventative dental care for those on oral L-serine powder; social work support and care coordination as needed. Surveillance: Monitor for seizures, changes in tone, contractures, developmental and educational needs, behavior issues, growth and nutrition, constipation and feeding issues, respiratory issues, musculoskeletal manifestations, and family needs at each visit. Dental evaluation every six months. Assessment of care needs when transitioning from pediatric to adult care. Agents/circumstances to avoid: Known triggers of seizure activity (e.g., infection, physical stress, emotional stress). Evaluation of relatives at risk: It is appropriate to evaluate newborn sibs and apparently asymptomatic older and younger sibs of a proband to identify as early as possible those who would benefit from prompt initiation of L-serine treatment. Serine deficiency disorders are inherited in an autosomal recessive manner. If both parents are known to be heterozygous for a serine deficiency-causing pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of inheriting neither of the familial pathogenic variants. Once the serine deficiency-causing pathogenic variants have been identified in an affected family member, carrier testing for at-risk relatives and prenatal and preimplantation genetic testing are possible.

Warburg micro syndrome (WARBM) is a rare, autosomal recessive, neurodevelopmental disorder characterized by microcephaly, cortical dysplasia, corpus callosum hypoplasia, congenital hypotonia leading to subsequent spastic quadriplegia, severe developmental delay and hypogenitalism. Ophthalmologic findings that may affect any ocular segment including characteristic, small, atonic pupils. WARBM is known to be caused by biallelic, pathogenic variants in at least five genes although additional genetic loci may exist. The RAB3GAP1 c.748 + 1G>A, p.Asp250CysfsTer24 founder variant has been described in families of Turkish ancestry. We report the clinical and molecular findings in three, unrelated, Turkish families with WARBM. A novel c.974-2A>G variant causing WARBM in three siblings of Turkish descent was found. Functional studies of the novel, c.2606 + 1G>A variant in patients' mRNA revealed skipping of exon 22 which results in a premature stop codon in exon 23. However, the clinical consequences of this variant are blended given that the individual also had a maternally inherited chromosome 3q29 microduplication.

Homozygous pathogenic variants in WDR45B were first identified in six subjects from three unrelated families with global development delay, refractory seizures, spastic quadriplegia, and brain malformations. Since the initial report in 2018, no further cases have been described. In this report, we present 12 additional individuals from seven unrelated families and their clinical, radiological, and molecular findings. Six different variants in WDR45B were identified, five of which are novel. Microcephaly and global developmental delay were observed in all subjects, and seizures and spastic quadriplegia in most. Common findings on brain imaging include cerebral atrophy, ex vacuo ventricular dilatation, brainstem volume loss, and symmetric under-opercularization. El-Hattab-Alkuraya syndrome is associated with a consistent phenotype characterized by early onset cerebral atrophy resulting in microcephaly, developmental delay, spastic quadriplegia, and seizures. The phenotype appears to be more severe among individuals with loss-of-function variants whereas those with missense variants were less severely affected suggesting a potential genotype-phenotype correlation in this disorder. A brain imaging pattern emerges which is consistent among individuals with loss-of-function variants and could potentially alert the neuroradiologists or clinician to consider WDR45B-related El-Hattab-Alkuraya syndrome.