Incidence and Prevalence

 Incidence of the disorder group: Carbohydrate Metabolism Disorders

1 in 16000 live births

Galactosemia incidence in metabolic disorders

The birth prevalence of galactosaemia was 2.6 times greater in areas with a screening program. Estimated prevalence is between 1 in 30,000-60,000 live births. Galactosemia ratio in Pakistan population is 1:9634.

Prevalence

Local Prevalence

The study of 1997 A comparison of disease and gene frequencies of inborn errors of metabolism among different ethnic groups in the West Midlands, UK confirms that the incidence of IEM with autosomal recessive inheritance is approximately 10 times greater among the UK Pakistani population than among North West Europeans. The increase was found to be in association with the presence of inter-marriages. Also the study indicated the attendance of Pakistanis at regional genetic clinics is relatively low, and it has been suggested that their awareness of genetic conditions, and the amount of educational material available to them, is inadequate.

Global Prevalence

Galactosemia is a rare genetic, metabolic disorder with incidence of 1:78000 in New York State and approximately 30 cases per 100,000 live births. Among the White Americans it is around 1 in 47000 in UK 1 in 70000, and in Ireland 1 in 23000. It is increased among itinerants to 1:700 while it is highly frequent in the traveler community as 1 in 480. In the United States, 1% of the North American people are carriers which suggest a disease frequency of 1 in 40000. Its incidence is about 1 per 60,000 births for people of European ancestry.

The incidence seems to be rather lower among people of African and Asian descent. In the west European people, the percents of galactosemia are from 1: 23000 to 1: 44000. The disorder is thought to be much less common among the Asian people. Galactosemia occurs in all races; however, its variants are based on the exact gene defect. The variants are most notable among African – Americans.

 

Country	Extrapolated prevalence	Population estimated
USA	9.788	293.665.405
Turkey	2.296	68.893.918
Afghanistan	950	28.513.677
India	35502	1065070607
Pakistan	5306	104.196.336
Gaza strip	44	1.324.991
Iran	2250	67.503.205
Iraq	845	25.374.691
Israel	206	6.199.008
Jordan	187	5.611.202
Kuwait	75	2.257.549
Lebanon	125	3.777.218
Saudi Arabia	859	25.795.938
Syria	600	18.016.874
United Arab Emirates	84	2.523.915
West Bank	77	2.311.204
Yemen	667	20.024.867

Table 1: Prevalence of Galctosemia 

What is Galactosaemia?

 Physical Features

According to a study in 1999, the most common presenting clinical features are jaundice in 77% of the patients, failure to thrive 62%, and cataracts 54%. Few might have complete absence of GALT activity. If two infants display acute toxicity symptoms and positive urine galactose, they exhibit normal GALT activity.

Infants with galactosemia can develop symptoms in the first few days of life if they eat formula or breast milk that contains lactose. (The symptoms may be due to a serious blood infection with the bacteria E. coli.) :

• Convulsions
• Irritability
• Lethargy
• Poor feeding (baby refuses to eat formula containing milk)
• Poor weight gain
• Yellow skin and whites of the eyes (jaundice)
• Vomiting
• Cataracts

Without treatment, mortality in infants with galactosemia is about 75%. (Vantyghem et al., 2017)

Cause:

It is due to the defect that is deficiency of the enzyme Galactose 1 phophate Uridyl transferase (GAL-1-PUT). Galactosemia has an Autosomal recessive mode of inheritance that leads to a deficiency in the enzyme GAL-1-PUT which is essential for galactose metabolism. Galactosemia might be caused by two causes:

Deficient eynzme	Galactokinase	Galactose-1-phosphate uridyltransferase
Relative frequency	·       Rare	·       Common (classic galactosemia)
Role of enyzme	·       Converts galactose to galactose-1-phosphate	·       Converts galactose-1-phosphate to UDP-galactose.
Disease severity	·       Mild	·       Severe
Clinical features	·       Cataracts	·       Poor feeding ·       Failure to thrive ·       Vomiting, diarrhea ·       Jaundice ·       Hepatomegaly ·       Cataracts ·       Cognitive impairment ·       ↑ Risk of E. coli sepsis ·       Hypoglycemia

Table 2: Types of Galactosemia

 

Testing and the follow-up

• Urine test: to be screened for the presence of a reducing substance using urinary dipstick followed by thin layer chromatography to establish the presence of galactosaemia.
• The Beutler’s test screens for galactosemia by detecting the level of enzyme of the infant. Therefore, the ingestion of formula or breast milk does not affect the outcome of this part of the NBS, and the NBS is accurate for detecting galactosemia prior to any ingestion of galactose.
• GALT test: The diagnosis of galacotosaemia should then be confirmed by analysis of galactose-1 phosphate uridyl transferase (GALT) activity in the erythrocytes using the established Beutler enzyme assay procedure. Age and sex-matched samples were used as controls for GALT activity.
• Physical examination: The presenting clinical features of each patient on admission were also recorded.

 

Confirmation Tests

• Excel Labs aims to deliver the highest quality patient care, everyday, for everyone, and become a leading pathology laboratory for comprehensive diagnostic services. They do not provide these tests. They will send samples to the labs abroad.
  • Enzyme Assay test:
    • GALT / Galactose-1-Phosphate Uridyltransferase (GALT), Blood: TEST PRICE WILL BE Rs. 6500.
  • Mutational Genetic Tests:
    • Galactosemia (sequence analysis of GALT gene) TEST PRICE WILL BE Rs. 172000
      • – specimen type: Peripheral blood in EDTA container
    • Galactosemia (deletion/duplication analysis on GALT gene) : TEST PRICE WILL BE Rs 99000

In case of more inquiries regarding the confirmatory tests, please call ZBF Islamabad office: 051-5732124

 

 Treatment

• Dietary limitation:
  • Complete cessation of lactose-containing feeds and lifelong adherence to a galactose-free and lactose-free diet: Patients confirmed to have galactosaemia are to be immediately placed on a galactose free diet. People with this condition must avoid all milk, milk-containing products (including dry milk), and other foods that contain galactose for life. It is essential to read product labels and be an informed consumer.
  • Infants can be fed with:
    • Soy formula
    • Meat-based formula or Nutramigen (a protein hydrolysate formula)
    • Another lactose-free formula
    • Calcium supplements are recommended.
  • Oestrogen from 12-13 years; then + progestins
  • Discuss recombinant FSH/oocyte cryopreservation
  • Osteoporosis: Calcium ± vitamin D ± diphophonates

 

Outcomes

• Starting treatment shortly after birth can help prevent developmental delays and intellectual disabilities. This is why newborn screening for classic galactosemia (GALT) is so important.
• Some children with mild forms of GALT may not need any special treatment.
• Even if a child avoids all foods that contain galactose, a small buildup of undigested sugars may still occur because the human body makes a small amount of this on its own. Some children with classic galactosemia who receive treatment early still show delays in learning, development, speech/language, and motor skills.
• Without treatment, babies with GALT are at risk of developing vision trouble, liver trouble, low blood sugar (called hypoglycemia), blood infections, developmental delays, and intellectual disabilities. Babies who do not receive treatment can die within their first weeks or months of life.
• Galactosemic girls, whether well-treated or not, run a considerable risk of developing ovarian dysfunction.
• Mild hypergonadotropinism has been documented in only 2 galactosemic males, but the male cohort of galactosemics studied for gonadal dysfunction is yet small.

 

References

1. Vantyghem, M., Dobbelaere, D., Mention, K., Wemeau, J., Saudubray, J. and Douillard, C. (2017). Endocrine manifestations related to inherited metabolic diseases in adults.

2. (2017). Galactosemia and Glycogen Storage Disease. [online] Available at: https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/appendix-a-diseases-injuries-and-disorders-of-the-organ-systems-1416/diseases-and-disorders-of-the-metabolism-1474/galactosemia-and-glycogen-storage-disease-1476-7786/ [Accessed 24 Jun. 2017].

3. org. (2017). Available at: http://www.phgfoundation.org/file/2515 [Accessed 24 Jun. 2017].

4. MSD Manual Consumer Version. (2017). Endocrine Disorders – Hormonal and Metabolic Disorders – MSD Manual Consumer Version. [online] Available at: http://www.msdmanuals.com/home/hormonal-and-metabolic-disorders/biology-of-the-endocrine-system/endocrine-disorders [Accessed 24 Jun. 2017].

5. medscape.com. (2017). Inherited Metabolic Disorders Overview: Overview, Clinical Features and Differential Diagnosis, Epidemiology and Statistics. [online] Available at: http://emedicine.medscape.com/article/1183253-overview#a7 [Accessed 24 Jun. 2017]

Emedicine.medscape.com. (2017). Inherited Metabolic Disorders Overview: Overview, Clinical Features and Differential Diagnosis, Epidemiology and Statistics. [online] Available at: http://emedicine.medscape.com/article/1183253-overview#a7 [Accessed 24 Jun. 2017