Galloway-Mowat Syndrome: Causes, Symptoms, and Management

Galloway-Mowat syndrome is a rare inherited condition defined by two hallmark features appearing together: steroid-resistant nephrotic syndrome, in which the kidneys leak large amounts of protein, and microcephaly accompanied by structural brain abnormalities.¹ Despite being recognized for more than half a century, the syndrome remains underdiagnosed because mutations in at least ten different genes can cause it, and the severity of kidney and brain involvement varies widely from one patient to the next.

How the Syndrome Was First Recognized

In 1968, two physicians named Galloway and Mowat described siblings from an unrelated (non-consanguineous) family who shared three unusual findings: microcephaly, hiatal hernia, and nephrotic syndrome. That was the first time anyone had reported those features clustering in siblings, which hinted at a genetic explanation. Over the following decades, additional patients with strikingly similar presentations were described around the world, and clinicians noticed that eye, ear, and broader nervous-system abnormalities appeared frequently enough to suggest a full-blown syndrome rather than a coincidence of separate problems.¹ The condition follows an autosomal recessive inheritance pattern in most cases, meaning a child typically needs to inherit a defective copy of the responsible gene from each parent to develop the disease. One exception is the gene LAGE3, which sits on the X chromosome and follows an X-linked pattern instead.

The Genetic Landscape

For a long time, the genetic basis of Galloway-Mowat syndrome was a mystery. The first breakthrough came in 2014, when researchers identified mutations in a gene called WDR73 in two unrelated families whose children had the syndrome. Affected individuals with WDR73 mutations tend to develop nephrotic syndrome later in childhood rather than in the newborn period, along with postnatal microcephaly, severe intellectual disability, and a recognizable pattern of findings on brain MRI.²

A few years later, a much larger group of genes entered the picture. In 2017, researchers reported that mutations in four genes encoding the subunits of something called the KEOPS complex, specifically OSGEP, TP53RK, TPRKB, and LAGE3, were responsible for the syndrome in 37 individuals from 32 families.³ Shortly afterward, mutations in a fifth KEOPS subunit gene, GON7, and in a partner gene called YRDC were also linked to the syndrome.⁴

Beyond the KEOPS pathway and WDR73, mutations in genes for nuclear pore components have been identified in patients with a very similar presentation. For example, a homozygous variant in NUP107, which encodes a protein that helps form the channels through which molecules move in and out of the cell nucleus, was found in two consanguineous Turkish families whose children had microcephaly and steroid-resistant nephrotic syndrome closely resembling the syndrome.⁵ Additional genes like NUP133, WDR4, and PRDM15 have also been implicated, which underscores how genetically diverse this single clinical diagnosis can be.¹

What the KEOPS Complex Actually Does

The KEOPS complex carries out a chemical modification on transfer RNA (tRNA), the molecules that ferry amino acids to the ribosome during protein assembly. Specifically, it adds a small chemical group to a precise spot on certain tRNAs, a modification abbreviated as t6A. This modification is essential for the ribosome to read the genetic code accurately and build proteins at the correct speed.⁴ When mutations cripple any subunit of the KEOPS complex, protein production goes awry in cells that are especially dependent on precise translation, and the kidneys and brain happen to top that list.

The KEOPS complex is ancient in evolutionary terms. Yeast use the same five-subunit machinery to carry out the t6A modification, and yeast studies have also revealed that the complex plays an additional role in maintaining the caps at the ends of chromosomes, called telomeres.⁶ Whether the telomere function contributes to the human disease is still being worked out, but the deep evolutionary conservation of the complex helps explain why yeast and cell-culture models have been useful platforms for studying how individual mutations disrupt the complex’s function.

How WDR73 Damages Kidney Cells

The kidney’s filtering units, called glomeruli, rely on specialized cells known as podocytes that wrap around tiny capillaries and control what passes through. WDR73 appears to be important for keeping podocytes anchored and structurally intact. In mouse experiments, deleting WDR73 specifically in podocytes did not immediately destroy the kidneys under normal conditions, but when the kidneys were challenged with a drug that stresses podocytes, the mice developed heavy protein loss in urine and visible damage to the foot-like projections that podocytes extend around capillaries. The underlying problem was traced to impaired formation of focal adhesions, the molecular anchors that attach a cell to its surroundings.⁷ Focal adhesions are critical for podocytes because these cells sit under constant mechanical stress from blood pressure pushing fluid through the filter. Lose those anchors, and the filter starts to leak protein.

This mechanism is somewhat distinct from what goes wrong with KEOPS mutations, where the root issue is faulty tRNA modification rather than cytoskeletal anchoring. The fact that very different cellular pathways converge on the same clinical picture, kidney failure plus brain malformation, tells researchers that both pathways feed into cell types (podocytes and developing neurons) that are unusually sensitive to disruption.

Neurological Features

Brain involvement in Galloway-Mowat syndrome goes well beyond a small head circumference. A systematic review of patients with WDR73 mutations found that microcephaly was present in about 86 percent of cases, cerebellar atrophy in a similar proportion, and eye abnormalities in roughly 84 percent. Weak trunk muscle tone (axial hypotonia) was documented in about 81 percent, and movement disorders in around 63 percent.⁸

The specific brain-imaging findings can vary by the gene involved. In a group of Taiwanese patients with OSGEP mutations, brain MRI consistently showed pachygyria (a pattern of abnormally thick, smooth brain folds) and poor myelination, meaning the insulation that normally coats nerve fibers was underdeveloped. These abnormalities were detectable even before birth on fetal MRI in some cases.⁹ In contrast, WDR73-related cases tend to show cerebellar atrophy and a more homogeneous MRI pattern rather than the cortical malformations seen with KEOPS gene mutations.²

Seizures, developmental delay, and intellectual disability appear across virtually all genetic subtypes, though their severity ranges from mild cognitive impairment in some children to profound disability in others. Eye problems, which can include optic atrophy, strabismus, and abnormal eye movements, are common enough to warrant an ophthalmologic evaluation early in the diagnostic workup.

Kidney Disease and Its Progression

The kidney side of the syndrome presents as nephrotic syndrome, most recognizably as heavy proteinuria, low blood albumin, and swelling. A critical feature is that the protein loss does not respond to steroids, which distinguishes it from many other childhood nephrotic syndromes and limits the available drug options. The age when kidney disease becomes apparent varies considerably. With KEOPS gene mutations, nephrotic syndrome can appear in the first weeks of life. With WDR73 mutations, it tends to emerge later in childhood. In an Iranian case involving an OSGEP mutation, the patient survived to age twelve with intellectual disability, seizures, and nephrotic syndrome, suggesting that the trajectory is not always rapidly progressive.¹⁰

Under the microscope, the kidney damage is distinctive. Early pathological studies of newborns with the syndrome found that the glomerular architecture was disorganized: capillary walls stuck together, mesangial zones were poorly defined, and the glomerular basement membrane, the scaffold that supports the filter, had lost its normal layered structure. In its place, researchers found flocculent material and unusual tiny fibrils of unknown composition infiltrating the space between the cells that line the capillaries and the podocytes that wrap around them.¹¹ Other patterns seen on kidney biopsy across the broader patient population include focal segmental glomerulosclerosis (FSGS), diffuse mesangial sclerosis, and minimal-change disease, though the underlying genetic defect rather than the histologic label is what defines the syndrome.

How the Diagnosis Is Made

There is no single blood test for Galloway-Mowat syndrome. Diagnosis typically starts with clinical recognition: a child presenting with steroid-resistant nephrotic syndrome and microcephaly, especially when there is a family history of consanguinity, should raise the suspicion. Brain imaging adds supportive evidence when it reveals characteristic patterns such as cerebellar atrophy, pachygyria, or poor myelination. The definitive step is genetic testing, usually whole-exome sequencing, which can identify mutations across the growing list of implicated genes.

Diagnostic delay is a real problem. In one reported family with a LAGE3 mutation, seven male members died prematurely before the underlying genetic cause was identified, and three of them had documented nephrotic syndrome.¹² Because LAGE3 sits on the X chromosome, the disease in that family followed an X-linked pattern, disproportionately affecting boys. The overall symptoms from LAGE3 mutations were milder compared with other genetic subtypes, which may have further delayed recognition. Genetic testing of at-risk family members after the first confirmed case can prevent the syndrome from going undiagnosed in subsequent children, and it provides essential information for prenatal counseling.

Management and Treatment Options

No therapy reverses or halts the underlying genetic defect. Management is therefore supportive and multidisciplinary, addressing each organ system individually. On the kidney side, treatment follows the general approach to steroid-resistant nephrotic syndrome: controlling proteinuria with medications that lower pressure in the kidney’s filtering units (typically ACE inhibitors or angiotensin receptor blockers), managing edema with diuretics, and monitoring nutritional status because chronic protein loss depletes albumin and can impair growth.

When kidney function deteriorates to end-stage disease, dialysis becomes necessary, and transplantation enters the conversation. Because the kidney disease in Galloway-Mowat syndrome is caused by the patient’s own genetic defect in podocytes, a transplanted kidney from a healthy donor does not carry the same mutation and is therefore not expected to develop the same disease pattern. A multicenter Japanese study examining kidney transplantation in pediatric patients with intellectual disability found that transplantation was not contraindicated in these patients, though decisions must weigh the child’s overall neurologic prognosis and the family’s capacity to manage post-transplant care.¹³

Neurological management includes antiepileptic drugs for seizures, physical and occupational therapy for motor delays and hypotonia, and speech therapy when language development is affected. Because eye abnormalities are common, regular ophthalmologic follow-up helps catch treatable conditions like refractive errors or strabismus early. Nutritional support is often necessary, as feeding difficulties are frequent in children with significant neurologic involvement.

Genotype-Phenotype Patterns and Prognosis

One of the hardest aspects of Galloway-Mowat syndrome for families is its unpredictable severity. Nevertheless, some patterns are emerging as more patients are genetically characterized. KEOPS complex mutations, particularly in OSGEP, tend to cause the most severe form with early-onset nephrotic syndrome and prominent brain malformations including pachygyria. LAGE3 mutations appear to cause milder disease on average.¹² WDR73 mutations occupy something of a middle ground, with later-onset kidney disease but often significant cerebellar and cognitive involvement.⁸

Overall mortality remains high, particularly in children with KEOPS pathway mutations who develop nephrotic syndrome in the newborn period. Many affected infants do not survive beyond the first few years of life. Children with later-onset forms, especially those with WDR73 or milder OSGEP mutations, may survive into adolescence or beyond, though they generally require lifelong medical support. Identifying the specific genetic cause early helps clinicians give families a more realistic picture of what to expect and tailor surveillance accordingly.

Why Consanguinity Keeps Coming Up

Many reported cases of Galloway-Mowat syndrome involve children born to parents who are blood relatives. This is not a coincidence. Because the syndrome is autosomal recessive in most genetic subtypes, each parent must carry one defective copy of the same gene. In populations where consanguineous marriage is common, the chance that both parents carry the same rare mutation is significantly higher than in outbred populations. The Taiwanese cohort with OSGEP mutations, the Turkish families with NUP107 mutations, and the Iranian family with a novel OSGEP variant all involved consanguineous parents.¹⁰⁵ This does not mean the syndrome cannot occur in non-consanguineous families; it can, when both parents happen to carry the same rare variant by chance. But consanguinity dramatically raises the odds, and genetic counseling in these communities is particularly valuable for identifying carrier status.

Research Models and Open Questions

Because Galloway-Mowat syndrome is so rare, much of what scientists understand about its biology comes from model systems. Yeast have been invaluable for studying the KEOPS complex because the genes are highly conserved across species. In the budding yeast Saccharomyces cerevisiae, the equivalent complex carries out the same t6A tRNA modification and also participates in telomere maintenance and DNA repair.¹⁴ Introducing patient-derived mutations into yeast versions of the KEOPS genes and measuring how badly the modification or telomere functions break down gives researchers a fast, inexpensive way to gauge whether a newly discovered variant is truly disease-causing.

Mouse models have been developed as well, including podocyte-specific WDR73 knockout mice that helped reveal the focal adhesion defect described earlier.⁷ These models are essential stepping stones toward potential therapies, because they allow researchers to test whether stabilizing focal adhesions or boosting tRNA modification could slow kidney or brain damage. No such targeted therapy exists yet, and given the rarity of the condition, any future treatment will likely emerge from small, carefully designed trials rather than large-scale drug development programs. Gene therapy is a theoretical possibility, particularly for single-gene forms, but the challenge of delivering a corrective gene to both developing neurons and kidney podocytes simultaneously remains formidable.

Perhaps the most immediate open question is simply how many patients are going undiagnosed. The steady expansion of known causative genes, from one in 2014 to roughly ten today, suggests that clinicians who are not specifically looking for the syndrome may attribute its individual features to unrelated conditions. Wider adoption of whole-exome sequencing in children with unexplained nephrotic syndrome and microcephaly would almost certainly expand the recognized patient population and, in turn, improve our understanding of the syndrome’s full clinical spectrum.