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Chromosome 2: Genes, Abnormalities and Disorders

Chromosome number 2 is among the 23 pairs of the human chromosome, a submetacentric chromosome with a length of 242, 193,529 bp in length having approximately 1767 coding genes. 

Present in a pair, the present set of chromosomes possesses a total of 8% of genomic DNA having 242 million bp DNA sequences on it. The sequences are coding genes, non-coding genes, pseudogenes and other repetitive junk DNA as well. 

Type Sub Metacentric 
Type Autosome 
Length 242,193, 529bp 
Coding genes 1,300
Non-coding genes 1,767
Short variants 59, 777, 797
Pseudogenes 1,079 

The number of cytological indications: 

Cytological defectsTotal numbers 
Deletions 5
Duplications 1
Translocations 624
Inversion 7
Insertion 2
Other 

Chromosome 2 abnormalities: 

Many different chromosome disorders such as inversion, translocation, duplication, deletions, trisomies and others are reported on chromosome 2. 

chromosome 2 Inversions: 

Reported inversions- 3 

  • inv(2)(p23q13)- Acute myloid leukemia, juvenile myelomonocytic leukemia
  • inv(2)(p23q35)- Anaplasic large cell lymphoma
  • inv(2)(p21p23)- Acute lymphoblastic leukemia, chronic lymphoblastic leukemai T-cell lymphoma

Chromosome 2 Deletions:

When a chromosome part is missing regards as deletion or chromosome deletion. Here are some of the deletions:

  • del(2)(p16p23)- not known
  • del(2)(q23q35)- Uterus-adenocarcenoma
  • del(2)(q24q24)- Breast- adenocarcenoma
  • del(2)(p22p22)- Acute myloid leukemia
  • del(2)(p11.2p13)-
  • del(2)(p16p21/22)-
  • 2p distal deletions
  • del(2)(q14.1q21)- connective tissue laxity and attention deficit disorder
  • del(2)(q37q37)- varied symptoms including developmental delay, hypotonia and low muscle tone.
  • del (q23.2); del(2)(q24)- developmental delay and intellectual disability

Chromosome 2 duplications:

When a part of a chromosome gets duplicated, or the copies of genes doubled, is referred to as chromosome duplication.

  • dup(2)(q14q14)- primitive Neuroctoderamal tumor/ medulloblastoma
  • dup(2)(p25.1p25.3)- growth retardation
  • dup(2)(q31.3q36.3)- varied structural and developmental abnormalities.

Chromosome 2 translocations:

Translocation is when a part of a chromosome is missing and inserted into another location on another chromosome or the same chromosome. More than 625 translocations are reported on chromosome 2.

  • t(2;3)(p15-23;q26-27)- Acute myeloid leukemia, chronic myelogenous leukemia and chronic myelomonocytic leukemia.
  • t(2;19)(p23;p13)- Anaplastic large cell lymphoma

Trisomy 2:

Trisomy 2 mosaic- one extra copy of chromosome 2 full or partial present with a pair. Common symptoms including mild to moderate intellectual disability, developmental delay and other birth defects.

List of chromosome 2 disorders:

Waardenburg syndromeAutism synesthesia
Nonsyndromic deafness Primary pulmonary hypertension Gilbert’s syndrome
Congenital hypothyroidismHemochromatosis Harlequin type ichthyosis 
Ehlers-Danlos syndrome- classic and vascular 2p microdeletionAlport syndrome
Dementia with Lewy bodies Amyotrophic lateral sclerosis Crigler-Najjar type 1/2
Fibrodysplasia ossificans progessivaHemochromatosisHereditary nonpolyposis colorectal cancer 
Juvenile primary lateral sclerosis Nonsyndromic deafnessLactose intolerance
Primary hyperoxaluriaSitosterolemia Alstrom syndrome
Welander distal myopathy lissencephalyLiver cancer oncogenesis
Wrinkly skin syndromeCataracts Insulin-dependent diabetes Mellitus
T cell leukemia lymphomaOguchi disease 
Cystinuria Melanoma Ovarian cancer 

Common genetic disorders related to chromosome 2: 

  • Autism
  • Congenital hypothyroidism 
  • Hereditary nonpolyposis colorectal cancer 
  • Lactose intolerance 
  • Nonsyndromic deafness 
  • Primary pulmonary hypertension 

Autism:

Autism is a group of disorders that are neurodevelopmental defects that cause repetitive behavior, lack of social skills, developmental disabilities and communicational problems. 

Mutations in genes or alteration in chromosome 2 structure cause autism spectral disorders and varied intellectual disabilities. For example, 2q37 deletion syndrome is well known for its involvement in ASD which also causes other intellectual problems as well. 

Congenital hypothyroidism 

Congenital hypothyroidism (CHT) is a condition that occurs at birth and is common as well. Here the thyroid gland can’t produce the hormone “thyroid” properly. 

This happens because either the thyroid gland isn’t developed completely or is underdeveloped. Numerous gene and chromosome mutations cause CHT; the TPO gene is one of them. 

Lactose intolerance 

Lactose is one of the important ingredients of our diet, a king of carb. The condition of lactose intolerance arises when cells are unable to produce a sufficient amount of protein lactase. 

Meaning, lactose can not be digested thoroughly. The present condition is a digestive tract disorder caused by an inadequate amount of lactase enzyme. 

The gene LCT, located on chromosome 2 provides instruction making lactose. When it mutated, the present condition occurs. 

Hereditary nonpolyposis colorectal cancer, lung cancer, T cell leukemia, melanoma, lymphoma, AML, CML are other conditions that are caused by varied chromosomal aberrations such as translocations, deletions, duplications or inversions. We have enlisted some in the above portions. 

Wrapping up:

Chromosome 2 is a type of autosome so important for us to survive much like other chromosomes. However, no notable chromosome aberrations are present on chromosome 2.

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