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Microlissencephaly can be diagnosed by prenatal MRI. MRI is better than ultrasound when it comes to detecting microlissencephaly or MSGP prenatally.
The ideal time for proper prenatal diagnosis is between the 34th and 35th gestational week which is the time when the secondary gyration normally terminates. In microlissencephaly cases, the primary sulci would be unusually wide and flat while secondary sulci would be missing.
At birth, lissencephaly with a head circumference of less than minus three standard deviations (< –3 SD) is considered microlissencephaly.
Although genetic diagnosis in patients with MLIS is challenging, exome sequencing has been suggested to be a powerful diagnostic tool.
Prenatal Diagnosis:
- Aymé, "et al." (1989) reported prenatal diagnosis of Fryns syndrome by sonography between 24 and 27 weeks.
- Manouvrier-Hanu et al. (1996) described the prenatal diagnosis of Fryns syndrome by ultrasonographic detection of diaphragmatic hernia and cystic hygroma. The diagnosis was confirmed after termination of the pregnancy. The fetus also had 2 erupted incisors; natal teeth had not been mentioned in other cases of Fryns syndrome.
Differential Diagnosis:
- McPherson et al. (1993) noted the phenotypic overlap between Fryns syndrome and the Pallister–Killian syndrome (601803), which is a dysmorphic syndrome with tissue-specific mosaicism of tetrasomy 12p.
- Veldman et al. (2002) discussed the differentiation between Fryns syndrome and Pallister–Killian syndrome, noting that differentiation is important to genetic counseling because Fryns syndrome is an autosomal recessive disorder and Pallister–Killian syndrome is usually a sporadic chromosomal aberration. However, discrimination may be difficult due to the phenotypic similarity. In fact, in some infants with 'coarse face,' acral hypoplasia, and internal anomalies, the initial diagnosis of Fryns syndrome had to be changed because mosaicism of isochromosome 12p was detected in fibroblast cultures or kidney tissue. Although congenital diaphragmatic hernia is a common finding in both syndromes, bilateral congenital diaphragmatic hernia had been reported only in patients with Fryns syndrome until the report of the patient with Pallister–Killian syndrome by Veldman et al. (2002).
- Slavotinek (2004) reviewed the phenotypes of 52 reported cases of Fryns syndrome and reevaluated the diagnostic guidelines. She concluded that congenital diaphragmatic hernia and distal limb hypoplasia are strongly suggestive of Fryns syndrome, with other diagnostically relevant findings including pulmonary hypoplasia, craniofacial dysmorphism, polyhydramnios, and orofacial clefting. Slavotinek (2004) stated that other distinctive anomalies not mentioned in previous guidelines include ventricular dilatation or hydrocephalus, agenesis of the corpus callosum, abnormalities of the aorta, dilatation of the ureters, proximal thumbs, and broad clavicles.
Microlissencephaly is considered a more severe form than microcephaly with simplified gyral pattern. Microlissencephaly is characterized by a smooth cortical surface (absent sulci and gyri) with a thickened cortex (> 3 mm) and is usually associated with other congenital anomalies. Microcephaly with a simplified gyral pattern has too few sulci and normal cortical thickness (3 mm) and is usually an isolated anomaly.
Once the diagnosis of polymicrogyria has been established in an individual, the following approach can be used for discussion of prognosis:
A pregnancy history should be sought, with particular regard to infections, trauma, multiple gestations, and other documented problems. Screening for the common congenital infections associated with polymicrogyria with standard TORCH testing may be appropriate. Other specific tests targeting individual neurometabolic disorders can be obtained if clinically suggested.
The following may help in determining a genetic etiology:
Family history
It is important to ask for the presence of neurologic problems in family members, including seizures, cognitive delay, motor impairment, pseudobulbar signs, and focal weakness because many affected family members, particularly those who are older, may not have had MRI performed, even if these problems came to medical attention. In addition, although most individuals with polymicrogyria do present with neurologic difficulties in infancy, childhood, or adulthood, those with mild forms may have no obvious deficit or only minor manifestations, such as a simple lisp or isolated learning disability. Therefore, if a familial polymicrogyria syndrome is suspected, it may be reasonable to perform MRI on relatives who are asymptomatic or have what appear to be minor findings. The presence of consanguinity in a child's parents may suggest an autosomal recessive familial polymicrogyria syndrome.
Physical examination
A general physical examination of the proband may identify associated craniofacial, musculoskeletal, or visceral malformations that could indicate a particular syndrome. Neurologic examination should assess cognitive and mental abilities, cranial nerve function, motor function, deep tendon reflexes, sensory function, coordination, and gait (if appropriate).
Genetic testing
Suspicion of a chromosome abnormality is typically raised due to the presence of developmental delays or birth defects. Diagnosis of distal 18q- is usually made from a blood sample. A routine chromosome analysis, or karyotype, is usually used to make the initial diagnosis, although it may also be made by microarray analysis. Increasingly, microarray analysis is also being used to clarify breakpoints. Prenatal diagnosis is possible using amniocentesis or chorionic villus sampling.
The diagnosis is usually based on clinical features present at birth.
Ultrasound in the second trimester may show abnormalities associates with NLS, including polyhydramnios, intrauterine growth restriction, microcephaly, proptosis and decreased fetal motility.
At present, treatment for distal 18q- is symptomatic, meaning the focus is on treating the signs and symptoms of the conditions as they arise. To ensure early diagnosis and treatment, people with distal 18q- are suggested to undergo routine screenings for thyroid, hearing, and vision problems.
13q deletion syndrome can only be definitively diagnosed by genetic analysis, which can be done prenatally or after birth. Increased nuchal translucency in a first-trimester ultrasound may indicate the presence of 13q deletion.
A prenatal diagnostic is possible and very reliable when mother is carrier of the syndrome. First, it's necessary to determine the fetus' sex and then study X-chromosomes. In both cases, the probability to transfer the X-chromosome affected to the descendants is 50%. Male descendants who inherit the affected chromosome will express the symptoms of the syndrome, but females who do will be carriers.
Trisomy 9 can be detected prenatally with chorionic villus sampling and cordocentesis, and can be suggested by obstetric ultrasonography.
Because trisomy 9 may appear with mosaicism, it is suggested that doctors take samples from multiple tissues when karyotyping for diagnosis.
The prognosis is poor; affected individuals are either stillborn or die shortly after birth. The longest survival reported in literature is of 134 days.
This syndrome is transmitted as an autosomal recessive disorder and there is a risk for recurrence of 25% in future pregnancies.
Treatment of Aicardi syndrome primarily involves management of seizures and early/continuing intervention programs for developmental delays.
Additional comorbidities and complications sometimes seen with Aicardi syndrome include porencephalic cysts and hydrocephalus, and gastro-intestinal problems. Treatment for porencephalic cysts and/or hydrocephalus is often via a shunt or endoscopic of the cysts, though some require no treatment. Placement of a feeding tube, fundoplication, and surgeries to correct hernias or other gastrointestinal structural problems are sometimes used to treat gastro-intestinal issues.
Parents of a proband
- The parents of an affected individual are obligate heterozygotes and therefore carry one mutant allele.
- Heterozygotes (carriers) are asymptomatic.
Sibs of a proband
- At conception, each sibling of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
- Once an at-risk sibling is known to be unaffected, the risk of his/her being a carrier is 2/3.
- Heterozygotes (carriers) are asymptomatic.
Offspring of a proband
- Offspring of a proband are obligate heterozygotes and will therefore carry one mutant allele.
- In populations with a high rate of consanguinity, the offspring of a person with GPR56-related BFPP and a reproductive partner who is a carrier of GPR56-related BFPP have a 50% chance of inheriting two GPR56 disease-causing alleles and having BFPP and a 50% chance of being carriers.
Other family members of a proband.
- Each sibling of the proband's parents is at a 50% risk of being a carrier
Aicardi syndrome is typically characterized by the following triad of features - however, one of the "classic" features being missing does not preclude a diagnosis of Aicardi Syndrome, if other supporting features are present.
1. Partial or complete absence of the corpus callosum in the brain (agenesis of the corpus callosum);
2. Eye abnormalities known as "lacunae" of the retina that are quite specific to this disorder; [optic nerve coloboma]]; and
3. The development in infancy of seizures that are called infantile spasms.
Other types of defects of the brain such as microcephaly, polymicrogyria, porencephalic cysts and enlarged cerebral ventricles due to hydrocephalus are also common in Aicardi syndrome.
Even though clinical diagnostic criteria have not been 100 percent defined for genitopatellar syndrome, the researchers stated that the certain physical features could relate to KAT6B mutation and result in the molecular genetic testing. The researchers stated that the Individuals with two major features or one major feature and two minor features are likely to have a KAT6B mutation.
To diagnose the Genitopatellar Syndrome, there are multiple ways to evaluate.
Medical genetics consultation
- Evaluation by developmental specialist
- Feeding evaluation
- Baseline hearing evaluation
- Thyroid function tests
- Evaluation of males for cryptorchidism
- Orthopedic evaluation if contractures are present or feet/ankles are malpositioned
- Hip radiographs to evaluate for femoral head dislocation
- Renal ultrasound examination for hydronephrosis and cysts
- Echocardiogram for congenital heart defects
- Evaluation for laryngomalacia if respiratory issues are present
- Evaluation by gastroenterologist as needed, particularly if bowel malrotation is suspected
Recent research has found that Dandy–Walker syndrome often occurs in patients with PHACES syndrome.
This includes Ataxia-telegiectasia, Chédiak-Higashi syndrome, DiGeorge syndrome, Griscelli syndrome and Marinesco-Sjogren syndrome.
A diagnosis can be made on the combination of clinical features. This can then be confirmed by gene sequencing.
Treatment for individuals with Dandy–Walker Syndrome generally consists of treating the associated problems, if needed.
A special tube (shunt) to reduce intracranial pressure may be placed inside the skull to control swelling. Endoscopic third ventriculostomy is also an option.
Treatment may also consist of various therapies such as occupational therapy, physiotherapy, speech therapy or specialized education. Services of a teacher of students with blindness/visual impairment may be helpful if the eyes are affected.
The diagnostic work up usually includes and MRI of the brain, an EEG, ophthalmic examination and a cardiac ECHO.
Muscle biopsy - which is not commonly done - may show storage of abnormal material and secondary mitochondrial abnormalities in skeletal muscle. Other features that may be seen on muscle biopsy include variability in fibre size, increase in internal and centralized nuclei, type 1 fibre hypotrophy with normally sized type 2 fibres, increased glycogen storage and variable vacuoles on light microscopy
The diagnosis is confirmed by sequencing of the EPG5.
The prognosis for children with NMDs varies depending on the specific disorder and the degree of brain abnormality and subsequent neurological signs and symptoms.
Differential diagnosis includes Angelman syndrome, Mowat–Wilson syndrome and Rett syndrome.
Suspicion of a chromosome abnormality is typically raised due to the presence of developmental delays or birth defects. Diagnosis of ring 18 is usually made via a blood sample. A routine chromosome analysis, or karyotype, is usually used to make the initial diagnosis, although it may also be made by microarray analysis. Increasingly, microarray analysis is also being used to clarify breakpoints. Prenatal diagnosis is possible via amniocentesis or chorionic villus sampling.
Diagnosing colpocephaly prenatally is difficult because in many cases signs start to appear after birth. Prenatal diagnosis is made by detecting enlargement of either or both occipital horns of the lateral ventricles. Usually prenatal ultrasounds don't show cephalic abnormalities and in cases that they do show abnormality is of low accuracy, making it difficult to diagnose colpocephaly. Often, abnormalities in prenatal ultrasounds can be misdiagnosed as hydrocephalus.
Three dimensional (3D) T1W, Axial, coronal, sagittal imaging is excellent for differentiation between gray matter and white matter acquisition of high-resolution anatomic information.T2W, Axial and coronal imaging for acquisition of high-resolution anatomic information; delineation of cortex, white matter, and gray matter nuclei. Diffusion tensor, axial imaging is used for evaluation of white matter microstructural integrity, identification of white matter tracts. CISS, axial + MPR imaging for evaluation of cerebellar folia, cranial nerves, ventricles, and foramina. Susceptibility weighted axial scan for Identification and characterization of hemorrhage, blood products, calcification, and iron accumulation.