B4GALT1-CDG

What it is

From: Orphanet

B4GALT1-CDG is a congenital disorder of glycosylation characterised by macrocephaly due to Dandy-Walker malformation, hydrocephaly, hypotonia, myopathy and coagulation anomalies. To date, only one case has been reported. The syndrome is associated with mutations in the GALT1 gene (localised to region q13 of chromosome 9) leading to a deficiency in the Golgi apparatus enzyme beta-1,4-galactosyl transferase.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal enzyme/coenzyme activity · Very frequent (99-80%)

Concentration or activity of an enzyme is above or below the limits of normal in the blood circulation.

Elevated circulating creatine kinase concentration · Very frequent (99-80%)

The activity of creatine kinase in the blood circulation is above the upper limit of normal.

Floppy infant · Very frequent (99-80%)

Floppiness/hypotonia is defined as reduced resistance to passive movement of joints. Physical examination of floppy/hypotonic infants shows head lag, lack of shoulder and elbow muscle contraction on traction response, inability to tighten the shoulder girdle muscles (or slipping through) when held under the axillae, scarf sign (when the arm is pulled to the opposite side, the arm wraps around the neck with the elbow crossing midline), hyperdorsiflexion of the feet, easy apposition of the thumb against the forearm, feet touching the cheek with ease and without discomfort, frog leg position, and inverted U sign on ventral suspension (head, arms, and legs hanging down without elbow or knee flexion and the trunk rounded in a dome shape).

Type II transferrin isoform profile · Very frequent (99-80%)

Abnormal transferrin isoform profile consistent with a type II congenital disorder of glycosylation.

Abnormal facial shape · Frequent (79-30%)

An abnormal morphology (form) of the face or its components.

Abnormality of the coagulation cascade · Frequent (79-30%)

An abnormality of the coagulation cascade, which is comprised of the contact activation pathway (also known as the intrinsic pathway) and the tissue factor pathway (also known as the extrinsic pathway) as well as cofactors and regulators.

Axial hypotonia · Frequent (79-30%)

Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk.

Decreased LDL cholesterol concentration · Frequent (79-30%)

The concentration of low-density lipoprotein cholesterol in the blood circulation is below the lower limit of normal.

Elevated circulating hepatic transaminase concentration · Frequent (79-30%)

Elevations of the levels of SGOT and SGPT in the serum. SGOT (serum glutamic oxaloacetic transaminase) and SGPT (serum glutamic pyruvic transaminase) are transaminases primarily found in the liver and heart and are released into the bloodstream as the result of liver or heart damage. SGOT and SGPT are used clinically mainly as markers of liver damage.

Low-set ears · Frequent (79-30%)

Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear.

Myopia · Frequent (79-30%)

An abnormality of refraction characterized by the ability to see objects nearby clearly, while objects in the distance appear blurry.

Prolonged partial thromboplastin time · Frequent (79-30%)

Increased time to coagulation in the partial thromboplastin time (PTT) test, a measure of the intrinsic and common coagulation pathways. Phospholipid, and activator, and calcium are mixed into an anticoagulated plasma sample, and the time is measured until a thrombus forms.

Reduced antithrombin III activity · Frequent (79-30%)

An abnormality of coagulation related to a decreased concentration of antithrombin-III.

Reduced protein C activity · Frequent (79-30%)

An abnormality of coagulation related to a decreased concentration of vitamin K-dependent protein C. Protein C is activated to protein Ca by thrombin bound to thrombomodulin. Activated protein C degrades factors VIIIa and Va.

Other findings in the same source

From: Orphanet

Additional reported features include Reduced protein S activity (Frequent (79-30%)); Wide nasal bridge (Frequent (79-30%)); Abnormal bleeding (Occasional (29-5%)); Cerebellar hypoplasia (Occasional (29-5%)); Dandy-Walker malformation (Occasional (29-5%)); Diarrhea (Occasional (29-5%)); Edema (Occasional (29-5%)); Hepatomegaly (Occasional (29-5%)); High myopia (Occasional (29-5%)); Hydrocephalus (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Neonatal

Inheritance in the source

From: Orphanet

Autosomal recessive

Frequency and the population described

From: Orphanet

Reported case(s): 1.0; Worldwide. This is a published case count, not prevalence. Point prevalence: <1 / 1 000 000; Worldwide; Class only.

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing B4GALT1-CDG is Metabolic Medicine, with a metabolic specialist / clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with metabolic specialist / clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Is a biochemical or molecular result needed to clarify the diagnosis?
• Does this condition require an individual plan for illness or reduced food intake?
• Should nutrition advice come from a specialist metabolic dietitian?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for B4GALT1-CDG. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.