Skip to content
Use your HSA or FSA funds

Condition report · Neurological

Primary Microcephaly 26 (LMNB1)

Whole genome sequencing reads the LMNB1 gene for new changes that cause primary microcephaly 26, a condition in which the head and brain are smaller than expected from before birth.

A condition report looks for rare variants known to cause the conditions it covers.

Included in Premium and Premium + AI

Premium adds $99 per kit for the first year.

Order with Premium

About this condition

A rare condition in which the head and brain are smaller than expected from before birth, usually with intellectual disability. It is caused by a new change in one copy of the LMNB1 gene, which supports the structure of the cell nucleus.

Primary microcephaly 26 is a rare condition in which the head and brain are smaller than expected from before birth. The microcephaly is often severe and is usually accompanied by developmental delay and intellectual disability of varying degree. Short stature is common. Some people also have a simplified pattern of folds on the surface of the brain and an abnormal corpus callosum on brain scans.

The condition is caused by a new change in one copy of the LMNB1 gene. LMNB1 makes lamin B1, a structural protein of the nuclear envelope, which is the membrane that surrounds the nucleus of a cell. It is important for dividing brain cells. Most changes arise new, and the condition is autosomal dominant, so a child can inherit a change from an affected parent.

Care focuses on developmental and educational support and on growth monitoring. Parental testing and genetic counselling guide the recurrence risk, even though most cases arise new.

The condition we analyse

Autosomal dominant

Caused by changes in one copy of LMNB1 (lamin B1), a structural protein of the nuclear envelope important for dividing brain cells; most changes arise de novo. Extra copies (duplications) of LMNB1 cause a different, adult-onset leukodystrophy.

Signs and symptoms

Microcephaly present from birth, often severe, with developmental delay and intellectual disability of variable degree. Short stature is common. Some people have a simplified pattern of the brain's surface and an abnormal corpus callosum on brain scans.

What a diagnosis changes

Developmental and educational support and growth monitoring. Most cases arise de novo, but parental testing and genetic counselling guide recurrence risk.

Genes analysed

Also known as

MCPH26

MONDO:0030928OMIM 619179MedGen 1779629Sources: [1][2][3]

Why whole genome sequencing

Most cases of this condition arise from a new change, but parental testing still helps to guide recurrence risk. Whole genome sequencing reads LMNB1 in one test.

Two conditions from the same gene

Extra copies of LMNB1 cause a different condition, an adult-onset leukodystrophy that affects the white matter of the nervous system. The microcephaly described here is caused by changes in one copy of the gene and is a separate condition with its own features.

Growth and development are followed

Short stature is common, so growth is monitored over time alongside development. Developmental and educational support is the main part of care.

References

  1. Cristofoli F, Moss T, Moore HW, Devriendt K, Flanagan-Steet H, May M et al., 2020. De Novo Variants in LMNB1 Cause Pronounced Syndromic Microcephaly and Disruption of Nuclear Envelope Integrity. American journal of human genetics
  2. LMNB1 gene. MedlinePlus Genetics
  3. Raininko R, Gosky M, Padiath QS, 2016. LMNB1-Related Autosomal Dominant Leukodystrophy. GeneReviews

Other neurological conditions

All conditions →

One test. A lifetime of answers.

One kit, sent to your home. Your entire genome sequenced at the clinical standard used for diagnostic decisions. Physician-ready reports delivered to your Genome Manager in 6–8 weeks — permanent and updated as science advances.

From $449

Free shipping · Results in 6–8 weeks

Premium adds $99 per kit for the first year.

Order with Premium