Chromosome 5q deletion syndrome is very rare, and its exact prevalence is unknown. Only a limited number of individuals with constitutional 5q deletions have been reported in the medical literature. As chromosomal microarray testing has become more widely available, additional cases have been identified, expanding the recognized clinical spectrum. The disorder affects males and females equally.

Chromosome 5q deletion syndrome results from the loss of genetic material from chromosome 5q, with symptoms varying depending on the extent of genetic material deleted. This leads to haploinsufficiency of one or more genes (depending on the length of the deleted region) that are critical for normal development. The severity and specific clinical manifestations depend on the size and location of the deletion. Most cases occur de novo, meaning the deletion arises spontaneously during the formation of reproductive cells or early embryonic development. Less commonly, the deletion may be inherited from a parent with a balanced chromosomal rearrangement, such as a translocation. Several important developmental genes reside on chromosome 5q, and deletion of different regions produces distinct clinical phenotypes.

Clinical manifestations are highly variable but commonly include:

• Global developmental delay and delayed speech and language development

• Intellectual disability, ranging from mild to severe

• Hypotonia (low muscle tone) during infancy

• Growth delay and short stature

• Feeding difficulties and poor weight gain in infancy

• Distinctive facial features, which may include a broad forehead, widely spaced eyes (hypertelorism), a flat nasal bridge, low-set ears, and a small jaw (micrognathia)

• Congenital heart defects, including atrial or ventricular septal defects

• Skeletal abnormalities, such as scoliosis or limb anomalies

• Kidney or urinary tract abnormalities

• Behavioral disorders, autism spectrum disorder, attention-deficit/hyperactivity disorder (ADHD), or anxiety in some individuals

• Seizures, vision problems, or hearing impairment may occur depending on the genes affected

Because the deleted chromosomal regions vary considerably between patients, no two individuals have exactly the same combination or severity of symptoms.

The diagnosis is suspected in infants or children with unexplained developmental delay, congenital anomalies, or characteristic physical features. Confirmation requires genetic testing to identify the chromosomal deletion. A detailed family history and parental chromosome analysis help determine whether the deletion occurred spontaneously or was inherited.

• Chromosomal microarray analysis (CMA): The preferred first-line test for detecting chromosome 5q deletions and defining their size

• Conventional karyotyping: Identifies larger deletions and structural chromosome abnormalities

• Fluorescence in situ hybridization (FISH): May be used to confirm a deletion or evaluate family members

• Parental chromosome studies: Determine whether the deletion is de novo or associated with a balanced translocation

• Echocardiography: Screens for congenital heart defects

• Renal ultrasound: Evaluates for kidney and urinary tract abnormalities

• Developmental, neurological, hearing, and vision assessments: Identify associated functional impairments and guide intervention

While there is currently no cure for chromosome 5q deletion syndrome, treatment options are individualized and focus on managing symptoms, maximizing developmental potential, and addressing associated medical conditions. Management typically involves a multidisciplinary team and may include:

• Early intervention services, including physical, occupational, and speech therapy

• Special education and individualized educational programs

• Nutritional support and feeding therapy for infants with feeding difficulties

• Medical or surgical treatment of congenital heart defects or other structural abnormalities

• Orthopedic management for skeletal abnormalities

• Treatment of seizures, behavioral disorders, or other neurological complications as needed

• Genetic counseling for affected individuals and their families regarding recurrence risk and family planning

The prognosis depends largely on the size and location of the deletion and the severity of associated congenital abnormalities. Individuals with smaller deletions may have relatively mild developmental delays and achieve a high degree of independence, while those with larger deletions often have more significant intellectual disability and complex medical needs. Life expectancy is generally good when major congenital heart defects or other serious organ abnormalities are absent or successfully treated. Early diagnosis, comprehensive medical care, and developmental therapies can substantially improve functional outcomes and quality of life.

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