Cri du Chat & DiGeorge Syndromes: Case Studies

• Two cases are discussed: an 11-year-old female with suspected Cri du Chat syndrome and an 11-year-old male with suspected DiGeorge syndrome.

Case 1: 11-Year-Old Female (Cri du Chat Syndrome)

• Delayed motor and speech milestones are present.
• Antenatal bleeding occurred during the first trimester.
• Oligohydramnios was detected.
• Delivery was via C-section, 17 days before full term.
• Birth weight was low at 2.2 kilograms.
• Sucking issues and inadequate breastfeeding were noted.
• A high-pitched cry resembling a cat's meow was observed.
• Issues with neck control and turnover were attained at 8-9 months, later than typical.
• Babbles, but no other monotonic sounds are produced.
• Microcephaly (small head) is apparent.
• Hypertelorism (wide spacing of the eyes) is present.
• Low-set ears are noted.
• Pes planus (flat feet) is observed.
• Hypotonia (low muscle tone) is present.
• Temper tantrums and self-injurious behavior occur.
• No verbal communication is present.
• The genetic basis is a microdeletion on the short arm of chromosome 5, also known as 5p deletion syndrome or 5p minus syndrome.
• A high-pitched crying or meowing sound is a classic symptom reflecting the syndrome's name, "cry of the cat".
• Other features include microcephaly and hypertelorism, with possible congenital heart conditions and moderate to severe intellectual disability.
• Epicanthal folds and hypotonia may be present, resembling Down syndrome but without the classic facial features.
• Karyotype analysis should be performed to confirm the 5p deletion.

Case 2: 11-Year-Old Male (DiGeorge Syndrome)

• Seizures are present.
• Delivery was at term via vaginal delivery, birth weight was 3.7 kilos.
• Milestones are delayed; walked at two years and uttered first words at two and a half years.
• A coarse facial appearance including small ears, a narrowed forehead, and a long face is observed.
• Cardiac auscultation reveals a holosystolic murmur indicating a possible congenital cardiac condition.
• Hypocalcemia (low serum calcium levels) and low parathyroid hormone (PTH) levels are present.
• Thyroid hormones, cortisol, and prolactin levels are normal.
• Elevated urine calcium is noted.
• An echocardiogram shows a ventricular septal defect (VSD).
• Also called 22q11.2 deletion syndrome or velocardiofacial syndrome.
• Pure DiGeorge syndrome is emphasized by T-cell immune deficiency and hypocalcemic state.
• Velo cardio facial syndrome appears with milder immune deficiency, more pronounced dysmorphology, and cardiac defects.
• The condition involves a microdeletion on chromosome 22 that typically occurs spontaneously during gametogenesis.
• The TBX1 gene on chromosome 22 plays a role in pharyngeal pouch development which are critical for the formation of mouth structures, head, parathyroid glands, and thymus gland.
• Clinical features include parathyroid gland hypoplasia (low PTH secretion leading to hypocalcemia) and thymus gland aplasia or hypoplasia (reduced T lymphocyte production, increasing the risk for viral and fungal infections).
• Facial anomalies can include cleft palate, cleft lip, a long face with a broad nose, and small teeth.
• Patients may exhibit behavioral and mental health issues.
• Congenital heart conditions, particularly Tetralogy of Fallot, are typical. VSD and ASD are also common.
• Use the mnemonic CATCH 22 to remember features: cardiac abnormalities, abnormal facies, thymic hypoplasia, cleft palate, hypocalcemia, chromosome 22.

Other Syndromes

• Fragile X Syndrome: Features like long face, large ears, and intellectual disability may resemble this syndrome but would have a different genetic basis (X-linked).
• Klinefelter Syndrome: Can also show some facial features and intellectual issues, but usually associated with a 47,XXY karyotype, not a deletion syndrome.