Albright like syndrome
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Assosciate Editor(s)-In-Chief: Prashanth Saddala M.B.B.S
Synonyms and keywords: 2q37 microdeletion syndrome; Albright hereditary osteodystrophy 3; Albright hereditary osteodystrophy-like syndrome; brachydactyly-intellectual deficit; monosomy 2q37-qter
Overview
2q37 microdeletion syndrome is a chromosomal anomaly involving deletion of chromosome band 2q37 and manifests as three major clinical findings: developmental delay, skeletal malformations and facial dysmorphism.[1]
Pathophysiology
Genetics
The monosomy can be pure or can be associated with additional chromosomal imbalances.
The deletion involves the terminal region of chromosome 2 with breakpoints at or within band 2q37. Band 2q37 contains three sub-bands with over 80 genes being located in the 2q37.1-q37.3 region.
A few genotype-phenotype correlations have been identified including a critical region for the Albright hereditary osteodystrophy(AHO)-like phenotype and candidate genes for brachymetaphalangism, obesity and the autistic behavioral spectrum.
Associated Conditions
- Major malformations occur in 30% of patients with 2q37 deletions. Congenital heart, gastrointestinal (30% of patients), genitourinary (11% of cases) and central nervous system malformations (6% of patients) have been reported.
- Hypotonia is often present.
- Seizures are described in 35% of patients and behavioral anomalies are reported in about 30% of cases.
- Repetitive behavior and severe communication and social interaction deficits, stereotypic movements, intermittent aggressivity, hyperactivity, attention deficit disorder, obsessive-compulsive disorder and sleep disturbances are the characteristic features of a distinct subtype of autism associated with the 2q37 deletion.
Differentiating 2q37 microdeletion syndrome from other Diseases
The differential diagnosis should include other segmental aneusomy syndromes and Prader-Willi syndrome (see this term). AHO (pseudohypoparathyroidism; PHP) and pseudo-PHP (PPHP; see these terms) should also be included in the differential diagnosis but calcium, phosphorus, and parathormone levels are in the normal range in patients with deletion 2q37.
Epidemiology and Demographics
Incidence is estimated at less than 1 in 10,000 and more than 100 individuals have been reported.
Screening
Screening for a translocation should also be conducted as the deletion may be the result of the transmission of a derivative chromosome.
Natural History, Complications, and Prognosis
The prognosis depends on the malformations (cardiac, cerebral or intestinal) associated with the 2q37 deletion.
Diagnosis
Symptoms
Most of the initially reported patients had an Albright hereditary osteodystrophy-like phenotype (referred to as AHO3) with developmental delay or intellectual deficit, short stature (23% of patients), a tendency toward obesity with age, and brachymetaphalangism (50% of patients).
Physical Examination
Appearance of the Patient
Skin
- Sparse scalp hair
- Eczema is often present.
Head
- Microcephaly or Macrocephaly
- Round face
- Prominent forehead
- Midface hypoplasia
- Thin vermillion border of the lips
Eyes
Nose
- Depressed nasal bridge
- Deficient nasal alae
- Prominent columella
- V-shaped appearance of the nasal tip
Throat
Chest
Nipples are often widely set, distally placed or supernumerary.
Extremities
- Fifth finger clinodactyly
- Small feet/hands
- Syndactyly of the fingers or toes
- Persistent fetal finger pads
- Single palmar crease
Laboratory Findings
Biomarker Studies
Diagnosis relies on cytogenetic analysis and molecular characterization.
Treatment
Management of deletion 2q37 patients should be multidisciplinary and include a comprehensive evaluation of the major clinical criteria.
Speech, physical and occupational therapy are required.
Genetic Counseling
Antenatal diagnosis is feasible and genetic counseling should be proposed.