Some other disease-causing genes include: KATNB1 and WDR62. It is hypothesized that the KATNB1-associated microlissencephaly is the result of a combined effect of reduced neural progenitor populations and impaired interaction between the Katanin P80 subunit (encoded by KATNB1) and LIS1 (a.k.a. PAFAH1B1), a protein mutated in type 1 lissencephaly. Missense mutation in ACTG1 gene was identified in three cases of microlissencephaly. ACTG1 is the same gene that, when mutated, causes Baraitser-Winter syndrome. A loss-of-function mutation in the Doublesex- and Mab-3–Related Transcription factor A2 (DMRTA2, also known as DMRT5) gene has been reported in a case of microlissencephaly, implicating DMRTA2 as a critical regulator of cortical neural progenitor cell dynamics.Microlissencepahly is considered a tubulinopathy (tubulin gene defect) i.e. is caused by mutation in tubulin genes, mainly TUBA1A and less commonly TUBB2B, TUBB3, TUBA3E and TUBG1. Central pachygyria, polymicrogyria are more commonly seen in patients with defects in TUBB2B, TUBB3, and TUBB5. This implys the critical role of microtubule cytoskeleton in the pathophysiology of microlissencephaly as well as other neuronal migration disorders.Congenital infections like cytomegalovirus are also known to cause microlissencephaly.Both microlissencephaly and microcephaly with simplified gyral pattern result from either decreased stem cell proliferation or increased apoptosis in the germinal zone of the cerebral cortex. Diagnosis
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.
The advantages over open surgery are that percutaneous surgery is simpler, more straightforward and shorter concerning the duration. It can also be done in every other examination room unlike the open surgery, which is done in an operation room. The risk nonetheless is that the digital nerve of the thumb nearby can be damaged. Epidemiology
Not much research has been done on the epidemiology of congenital trigger thumbs. There are a few reports on the incidence in their respective studies. The most recent data comes from a Japanese study by Kukichi and Ogino where they found an incidence 3.3 trigger thumbs per 1,000 live births in 1-year-old children. References


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