The syndrome gets its name from the characteristic cry of affected infants, which is similar to that of a meowing kitten, due to problems with the larynx and nervous system. About 1/3 of children lose the cry by age of 2 years. Other symptoms of cri du chat syndrome may include:

- feeding problems because of difficulty in swallowing and sucking;

- low birth weight and poor growth;

- severe cognitive, speech, and motor delays;

- behavioral problems such as hyperactivity, aggression, outbursts, and repetitive movements;

- unusual facial features which may change over time;

- excessive drooling;

- small head and jaw;

- wide eyes;

- skin tags in front of eyes.

Other common findings include hypotonia, microcephaly, growth retardation, a round face with full cheeks, hypertelorism, epicanthal folds, down-slanting palpebral fissures, strabismus, flat nasal bridge, down-turned mouth, micrognathia, low-set ears, short fingers, single palmar creases, and cardiac defects (e.g., ventricular septal defect [VSD], atrial septal defect [ASD], patent ductus arteriosus [PDA], tetralogy of Fallot). Infertility is not associated with Cri du chat.

It has also been observed that people with the condition have difficulties communicating. While levels of proficiency can range from a few words to short sentences, it is often recommended by medical professionals for the child to undergo some sort of speech therapy/aid with the help of a professional.

Less frequently encountered findings include cleft lip and palate, preauricular tags and fistulas, thymic dysplasia, intestinal malrotation, megacolon, inguinal hernia, dislocated hips, cryptorchidism, hypospadias, rare renal malformations (e.g., horseshoe kidneys, renal ectopia or agenesis, hydronephrosis), clinodactyly of the fifth fingers, talipes equinovarus, pes planus, syndactyly of the second and third fingers and toes, oligosyndactyly, and hyperextensible joints. The syndrome may also include various dermatoglyphics, including transverse flexion creases, distal axial triradius, increased whorls and arches on digits, and a single palmar crease.

Late childhood and adolescence findings include significant intellectual disability, microcephaly, coarsening of facial features, prominent supraorbital ridges, deep-set eyes, hypoplastic nasal bridge, severe malocclusion, and scoliosis.

Affected females reach puberty, develop secondary sex characteristics, and menstruate at the usual time. The genital tract is usually normal in females except for a report of a bicornuate uterus. In males, testes are often small, but spermatogenesis is thought to be normal.

The syndrome is a rare clinical disorder.

- Physical

- Overgrowth

- Accelerated skeletal maturation

- Dysmorphic facial features

- Prominent eyes

- Bluish sclerae

- Coarse eyebrows

- Upturned nose

- Radiologic examination

- Accelerated osseous maturation

- Phalangeal abnormalities

- Tubular thinning of the long bones

- Skull abnormalities

- Mental

- Often associated with intellectual disability (of variable degree)

Acrocallosal syndrome (also known as ACLS) is a rare autosomal recessive syndrome characterized by corpus callosum agenesis, polydactyly, multiple dysmorphic features, motor and mental retardation, and other symptoms. The syndrome was first described by Albert Schinzel in 1979.

It is associated with "GLI3".

This syndrome consists a number of typical features. These include

- Agenesis of the corpus callosum (80-99% patients)

- Hypopigmentation of the eyes and hair (80-99% patients)

- Cardiomyopathy (80-99% patients)

- Combined immunodeficiency (80-99% patients)

- Muscular hypotonia (80-99% patients)

- Abnormality of retinal pigmentation (80-99% patients)

- Recurrent chest infections (80-99% patients)

- Abnormal EEG (80-99% patients)

- Intellectual disability (80-99% patients)

- Cataracts (75%)

- Seizures (65%)

- Renal abnormalities (15%)

Infections of the gastrointestinal and urinary tracts are common. Swallowing and feeding difficulties early on may result in a failure to thrive. Optic nerve hypoplasia, nystagmus and photophobia may occur. Facial dysmorphism (cleft lip/palate and micrognathia) and syndactyly may be present. Sensorineural hearing loss may also be present.

Death in infancy is not uncommon and is usually due to cardiac complications or severe infections.

Cri du chat syndrome, also known as chromosome 5p deletion syndrome, 5p− syndrome (pronounced "Five P Minus") or Lejeune’s syndrome, is a rare genetic disorder due to chromosome deletion on chromosome 5. Its name is a French term ("cat-cry" or "call of the cat") referring to the characteristic cat-like cry of affected children. It was first described by Jérôme Lejeune in 1963. The condition affects an estimated 1 in 50,000 live births across all ethnicities and is more common in females by a 4:3 ratio.

This includes Ataxia-telegiectasia, Chédiak-Higashi syndrome, DiGeorge syndrome, Griscelli syndrome and Marinesco-Sjogren syndrome.

8p23.1 duplication syndrome is a rare genetic disorder caused by a duplication of a region from human chromosome 8. This duplication syndrome has an estimated prevalence of 1 in 64,000 births and is the reciprocal of the 8p23.1 deletion syndrome. The 8p23.1 duplication is associated with a variable phenotype including one or more of speech delay, developmental delay, mild dysmorphism, with prominent forehead and arched eyebrows, and congenital heart disease (CHD).

The phenotypic data on 11 patients indicated that cases are not always ascertained for CHD but that CHD was the most common single feature found in 6 out of 11 individuals. Developmental delay and/or learning difficulties were found in 5 out of 11 cases, but one prenatal case was developing normally at 15 months of age (Case 1,). Three other prenatal cases could not yet be reliably assessed. A variable degree of facial dysmorphism was present in 5 out of 11 individuals. Partial toe syndactyly has been found in one mother and son diad and adrenal anomalies in two probands but not in the duplicated mother of one of them. The phenotype is compatible with independent adult life with varying degrees of support.

Duplication of the GATA4 transcription factor () is believed to underlie the congenital heart disease and other genes, common to the duplication and deletion syndromes, can be regarded as candidates for the 8p23.1 duplication syndrome. These include the SOX7 transcription factor () for both CHD and developmental delay and the TNKS gene () for behavioural difficulties. The diaphragmatic hernia found in the 8p23.1 deletion syndrome has not been found in the 8p23.1 duplication syndrome to date.

The duplication may be associated with copy number changes of the adjacent olfactory receptor/defensin repeats (ORDRs) that predispose to the 8p23.1 deletion and duplication syndromes. High total copy numbers of these repeats have been associated with predisposition to psoriasis and low copy number with predisposition to Crohn's disease.

Acrocallosal syndrome (ACLS, ACS, Schinzel-Type, Hallux-duplication) is a rare, heterogeneous [3] autosomal recessive disorder first discovered by Albert Schinzel (1979) in a 3-year-old boy . To inherit ACLS, one gene copy from each parent must contain a mutation somewhere in the KIF7 gene and be passed on to the child [3]. Characteristics of this syndrome include absence or poor development of the area connecting the left and right parts of the brain, an abnormally large head, increased distance between facial features (eyes), poor motor skills, mental retardation [2], extra fingers and toes, many facial deformities [3], and cleft palate [5]. This is considered a rare disorder and is placed on the NIH Office of Rare Diseases (fewer than 200,000 cases) rare disease list [8]. Lifespan may range from stillbirth to normal expectancy depending on pregnancy complications and severity of the disorder [2,3,5]. In mild cases, the subjects have been shown to live relatively normal lives, but with developmental delays [2].

Respiratory complications are often cause of death in early infancy.

Senior–Løken syndrome is a congenital eye disorder, first characterized in 1961. It is a rare, ciliopathic, autosomal recessive disorder characterized by nephronophthisis and progressive eye disease.

Revesz syndrome is a fatal disease that causes exudative retinopathy and bone marrow failure. Other symptoms include severe aplastic anemia, intrauterine growth retardation, fine sparse hair, fine reticulate skin pigmentation, ataxia due to cerebellar hypoplasia, and cerebral calcifications. Its effects are similar to that of Hoyeraal-Hreidarsson syndrome. It is a variant of dyskeratosis congenita.

Males show more serious symptoms than females affected by this disorder.

The symptoms for males are:

1. Profound sensorineural hearing loss i.e, a complete or almost complete loss of hearing caused by abnormalities in the inner ear.

2. Weak muscle tone - Hypotonia.

3. Impaired muscle coordination - Ataxia.

4. Developmental delay.

5. Intellecual disability.

6. Vision loss caused by optic nerve atrophy in early childhood.

7. Peripheral neuropathy.

8. Recurrent infections, especially in the respiratory system.

9. Muscle weakness caused by recurrent infections.

Symptoms for females:

Very rarely seen hearing loss that begins in adulthood (age > 20 years) combined with ataxia and neuropathy. Optic atrophy and retinitis pigmentosa observed in some cases too.

The fifth type of hyper-IgM syndrome has been characterized in three patients from France and Japan. The symptoms are similar to hyper IgM syndrome type 2, but the AICDA gene is intact. These three patients instead had mutations in the catalytic domain of uracil-DNA glycosylase, an enzyme that removes uracil from DNA. In both type 2 and type 5 hyper-IgM syndromes, the patients are profoundly deficient in IgG and IgA because the B cells can't carry out the recombination steps necessary to class-switch.

Recent findings in genetic research have suggested that a large number of genetic disorders, both genetic syndromes and genetic diseases, that were not previously identified in the medical literature as related, may be, in fact, highly related in the genetypical root cause of the widely varying, phenotypically-observed disorders. Such diseases are becoming known as ciliopathies. Known ciliopathies include primary ciliary dyskinesia, Bardet–Biedl syndrome, polycystic kidney and liver disease, nephronophthisis, Alström syndrome, Meckel–Gruber syndrome and some forms of retinal degeneration.

Revesz syndrome is a genetic disease thought to be caused by short telomeres. Patients with Revesz syndrome have presented with heterozygous mutations in TINF2 gene which is located on chromosome 14q12. There is no treatment for this disease yet.

Chromosome 5q deletion syndrome (chromosome 5q monosomy, 5q- syndrome) is an acquired, hematological disorder characterized by loss of part of the long arm (q arm, band 5q33.1) of human chromosome 5 in bone marrow myelocyte cells. This chromosome abnormality is most commonly associated with the myelodysplastic syndrome.

It should not be confused with "partial trisomy 5q", though both conditions have been observed in the same family.

This should not be confused with the germ line cri du chat (5p deletion) syndrome which is a deletion of the short arm of the 5th chromosome.

The rate of congenital heart disease in newborns with Down syndrome is around 40%. Of those with heart disease, about 80% have an atrioventricular septal defect or ventricular septal defect with the former being more common. Mitral valve problems become common as people age, even in those without heart problems at birth. Other problems that may occur include tetralogy of Fallot and patent ductus arteriosus. People with Down syndrome have a lower risk of hardening of the arteries.

Constipation occurs in nearly half of people with Down syndrome and may result in changes in behavior. One potential cause is Hirschsprung's disease, occurring in 2–15%, which is due to a lack of nerve cells controlling the colon. Other frequent congenital problems include duodenal atresia, pyloric stenosis, Meckel diverticulum, and imperforate anus. Celiac disease affects about 7–20% and gastroesophageal reflux disease is also more common.

Most affected people have a stable clinical course but are often transfusion dependent.

Chromosomal deletion syndromes result from deletion of parts of chromosomes. Depending on the location, size, and whom the deletion is inherited from, there are a few known different variations of chromosome deletions. Chromosomal deletion syndromes typically involve larger deletions that are visible using karyotyping techniques. Smaller deletions result in Microdeletion syndrome, which are detected using fluorescence in situ hybridization (FISH)

Examples of chromosomal deletion syndromes include 5p-Deletion (cri du chat syndrome), 4p-Deletion (Wolf-Hirschhorn syndrome), Prader–Willi syndrome, and Angelman syndrome.

People who are affected by Liebenberg Syndrome suffer from three main symptoms:

1. Dysplasia (improper formation) of the bony components of the elbow

2. Abnormal shape of carpal bones

3. Brachydactyly, a symptom where the fingers and toes are shorter than normal.

Arts syndrome is a rare metabolic disorder that causes serious neurological problems in males due to a malfunction of the PRPP synthetase 1 enzyme. Arts Syndrome is part of a spectrum of PRPS-1 related disorders with reduced activity of the enzyme that includes Charcot–Marie–Tooth disease and X-linked non-syndromic sensorineural deafness.

Microdeletion syndrome is a syndrome caused by a chromosomal deletion smaller than 5 million base pairs (5 Mb) spanning several genes that is too small to be detected by conventional cytogenetic methods or high resolution karyotyping (2–5 Mb). Detection is done by fluorescence in situ hybridization (FISH). Larger chromosomal deletion syndromes are detectable using karyotyping techniques.

Stage I, called early onset, typically begins between 6 and 18 months of age. This stage is often overlooked because symptoms of the disorder may be somewhat vague, and parents and doctors may not notice the subtle slowing of development at first. The infant may begin to show less eye contact and have reduced interest in toys. There may be delays in gross motor skills such as sitting or crawling. Hand-wringing and decreasing head growth may occur, but not enough to draw attention. This stage usually lasts for a few months but can continue for more than a year.